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The desire to understand how and why things happen is shared by all branches of what?
|
[
"population",
"society",
"science",
"government"
] |
C
|
Scientists may focus on very different aspects of the natural world. For example, some scientists focus on the world of tiny objects, such as atoms and molecules. Other scientists devote their attention to huge objects, such as the sun and other stars. But all scientists have at least one thing in common. They want to understand how and why things happen. Achieving this understanding is the goal of science.
It advocates the integration of "insiders", "outsiders" and multiple perspectives to obtain comprehensive and integrated understanding. It acknowledges that people have a complex and sophisticated understanding of themselves and it is necessary to translate their practical and episodic understanding into analytical knowledge. It is part of a scientific tradition that advocates multiple perspectives, but not multiple psychologies or absolute relativism.
This level of enquiry is based upon an exploration of the ontological categories (categories of being such as time and space). If the previous form of analysis emphasizes the different modes through which people live their commonalities with or differences from others, those same themes are examined through more abstract analytical lenses of different grounding forms of life: respectively, embodiment, spatiality, temporality, performativity and epistemology. At this level, generalizations can be made about the dominant modes of categorization in a social formation or in its fields of practice and discourse. It is only at this level that it makes sense to generalize across modes of being and to talk of ontological formations, societies as formed in the uneven dominance of formations of tribalism, traditionalism, modernism or postmodernism.
An entirely different body of research has focused on "collective memory", defined as "a set of shared representations of the past based on a shared identity among the members of a group". "These representations are considered both as activities of social elaboration and communication, as objects produced by this activity, and as symbolic contexts in which this activity takes place - and which it also helps to define". From this perspective, which sees memory as a collective phenomenon, many studies have focused on different social groups. The generations and nations that as a collective and social group engaged in conflictual relations, have received particular attention from the scientific community.
The theory posits that the evolutionary value of this organization lies in its use of the causal implications of the past and present to infer what may reasonably be expected to occur in the immediate future. This allows potential threats to be identified and evaluated and action to be taken to avoid or to reduce potential damage before the future actually arrives. This ongoing chronicle of one's experience is called one's prime narrative. It is the bedrock knowledge one has of one's world, the source of one’s intuitive reasoning, the basis of one’s private thought, and the source for one’s communications with others.
Instead of simply “taking in” new information, one goes back to look at their understandings and pulls together information that was “triggered” and forms a new connection. This connection becomes tighter and one's understanding of a certain concept is solidified or “stable” (Pangaro, 2003).
|
The scientific revolution took place where starting in the 1500s?
|
[
"africa",
"south america",
"europe",
"north america"
] |
C
|
People have probably wondered about the natural world for as long as there have been people. So it’s no surprise that science has roots that go back thousands of years. Some of the earliest contributions to science were made by Greek philosophers more than two thousand years ago. It wasn’t until many centuries later, however, that the scientific method and experimentation were introduced. The dawn of modern science occurred even more recently. It is generally traced back to the scientific revolution, which took place in Europe starting in the 1500s.
Kuhn, Thomas S. The Structure of Scientific Revolutions. 3rd ed. Chicago: University of Chicago Press, 1996.
Around 10,000 years ago, the Neolithic Revolution catalyzed an epochal transformation. Humanity transitioned from nomadic hunter-gatherer societies to stable agricultural communities.
La Philosophie de Jacob Boehme, Paris, J. Vrin, 1929. Études galiléennes, Paris: Hermann, 1939 From the Closed World to the Infinite Universe, Baltimore: Johns Hopkins Press, 1957 La Révolution astronomique: Copernic, Kepler, Borelli, Paris: Hermann, 1961 The Astronomical Revolution Methuen, London, 1973 Introduction à la lecture de Platon, Paris: Gallimard, 1994 Metaphysics & Measurement: Essays in Scientific Revolution Harvard University Press, 1968 A Documentary History of the Problem of Fall from Kepler to Newton, pp. 329–395, Transactions of the American Philosophical Society, Vol. 45, 1955 Newtonian Studies, Chapman & Hall, 1965
Newton, Alfred (1884). Ornithology.
Philosophes introduced the public to many scientific theories, most notably through the Encyclopédie and the popularization of Newtonianism by Voltaire and Émilie du Châtelet. Some historians have marked the 18th century as a drab period in the history of science. The century saw significant advancements in the practice of medicine, mathematics, and physics; the development of biological taxonomy; a new understanding of magnetism and electricity; and the maturation of chemistry as a discipline, which established the foundations of modern chemistry.
|
Ionic bonds are electrostatic attractions between two oppositely charged what?
|
[
"ions",
"molecules",
"gasses",
"compounds"
] |
A
|
Ionic bonds are electrostatic attractions between two oppositely charged ions. Ions can be formed and then bonded when metal atoms donate their valence electrons to nonmetal atoms.
This transfer causes one atom to assume a net positive charge, and the other to assume a net negative charge. The bond then results from electrostatic attraction between the positive and negatively charged ions. Ionic bonds may be seen as extreme examples of polarization in covalent bonds.
Ions of opposite charge are naturally attracted to each other by the electrostatic force. This is described by Coulomb's law: F = q 1 q 2 ε r 2 {\displaystyle F={\frac {q_{1}q_{2}}{\varepsilon r^{2}}}} where F is the force of attraction, q1 and q2 are the magnitudes of the electrical charges, ε is the dielectric constant of the medium and r is the distance between the ions. For ions in solution this is an approximation because the ions exert a polarizing effect on the solvent molecules that surround them, which attenuates the electric field somewhat. Nevertheless, some general conclusions can be inferred.
Ionic bonding is a kind of chemical bonding that arises from the mutual attraction of oppositely charged ions. Ions of like charge repel each other, and ions of opposite charge attract each other. Therefore, ions do not usually exist on their own, but will bind with ions of opposite charge to form a crystal lattice. The resulting compound is called an ionic compound, and is said to be held together by ionic bonding.
Some ionic compounds (salts) dissolve in water, which arises because of the attraction between positive and negative charges (see: solvation). For example, the salt's positive ions (e.g. Ag+) attract the partially negative oxygen atom in H2O. Likewise, the salt's negative ions (e.g. Cl−) attract the partially positive hydrogens in H2O. Note: the oxygen atom is partially negative because it is more electronegative than hydrogen, and vice versa (see: chemical polarity).
counterion The ion that is the counterpart to an oppositely charged ion in a dissociated ionic species; the cation that pairs with a given anion, or vice versa. For example, Na+ is the counterion to Cl−, and vice versa, in solutions of sodium chloride (NaCl). covalent bond Also molecular bond.
|
What is the theoretical event that began the universe often called?
|
[
"big bang",
"Coreolis effect",
"dark matter",
"string theory"
] |
A
|
The generation of an isolated but open system, which we might call a protocell, was a critical step in the origin of life. Such an isolated system has important properties that are likely to have facilitated the further development of life. For example, because of the membrane boundary, changes that occur within one such structure will not be shared with neighboring systems. Rather, they accumulated in, and favor the survival of, one system over its neighbors. Such systems can also reproduce in a crude way by fragmentation. If changes within one such system improved its stability, its ability to accumulate resources, or its ability to survive and reproduce, that system, and its progeny, would be likely to become more common. As these changes accumulate and are passed from parent to offspring, the organisms will inevitably evolve, as we will see in detail in the next chapter. As in living systems today, the earliest steps in the formation of the first organisms required a source of energy to maintain the non-equilibrium living system. There are really two choices for the source of this energy, either light (electromagnetic radiation from the sun) or thermodynamically unstable chemicals present in the environment. There have been a number of plausible scenarios, based on various observations, for the steps leading to life. For example, a recent study based on the analysis of the genes (and the proteins that they encode) found in modern organisms, suggests that the last universal common ancestor (LUCA) arose in association with hydrothermal vents.60 But whether this reflects LUCA or an ancestor of LUCA that became adapted to living is association with hydrothermal vents is difficult (and perhaps impossible) to resolve unambiguously, particularly since LUCA lived ~3.4-3.8 billion years ago and cannot be studied directly. Mapping the history of life on earth Assuming, as seems likely, that life arose spontaneously, we can now look at what we know about the fossil record to better understand the diversification of life and life’s impact on the Earth. This is probably best done by starting with what we know about where the Universe and Earth came from. The current scientific model for the origin of the universe is known as the “Big Bang” (also known as the “primeval atom” or the “cosmic egg”), an idea originally proposed by the priest, physicist and astronomer Georges Lemaître (1894-1966).61 The Big Bang model arose from efforts to answer the question of whether the fuzzy nebulae identified by astronomers were located within or outside of our galaxy. This required some way to determine how far these nebulae were from Earth. Edwin Hubble (1889-1953) and his co-workers were the first to realize that nebulae were in fact galaxies in their own right, each very much like our own Milky Way and each is composed of many billions of stars. This was a surprising result. It made Earth, sitting on the edge of one (the Milky Way) among many, many galaxies seem less important – a change in cosmological perspective similar to that associated with the idea that the Sun, rather than Earth, was the center of the solar system (and the Universe). To measure the movement of galaxies with respect to Earth, Hubble and colleagues combined to types of observations. The first of these allowed them to estimate the distance from the Earth to.
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fundamental questions about its origin, structure, evolution, and ultimate fate. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed those physical laws to be understood. Physical cosmology, as it is now understood, began with the development in 1915 of Albert Einstein's general theory of relativity, followed by major observational discoveries in the 1920s: first, Edwin Hubble discovered that the universe contains a huge number of external galaxies beyond the Milky Way; then, work by Vesto Slipher and others showed that the universe is expanding.
This has been put forward by J. Richard Gott III, James E. Gunn, David N. Schramm, and Beatrice Tinsley, who said that asking what occurred before the Big Bang is like asking what is north of the North Pole. However, some cosmologists and physicists do attempt to investigate causes for the Big Bang, using such scenarios as the collision of membranes.Philosopher Edward Feser argues that most of the classical philosophers' cosmological arguments for the existence of God do not depend on the Big Bang or whether the universe had a beginning. The question is not about what got things started or how long they have been going, but rather what keeps them going.
Cosmology studies how the universe came to be, and its eventual fate. It is studied by physicists and astrophysicists.
38 S437-S448 (Max Planck Institute for the History of Science) . doi:10.1088/0953-4075/38/9/001. Stachel, John, et al., Einstein's Miraculous Year. Princeton University Press, 1998. ISBN 0-691-05938-1.
The Nasadiya Sukta (RV 10.129) takes a near-agnostic stand on the creation of the primordial beings (such as the gods who performed the sacrifice of the Purusha), stating that the gods came into being after the world's creation, and nobody knows when the world first came into being. It asks who created the universe, does anyone really know, and whether it can ever be known. The Nasadiya Sukta states:
|
In the cardiovascular system, net filtration pressure represents the interaction of osmotic pressures and what other pressures?
|
[
"uptake",
"homeostatic",
"hydrophilic",
"hydrostatic"
] |
D
|
Interaction of Hydrostatic and Osmotic Pressures The normal unit used to express pressures within the cardiovascular system is millimeters of mercury (mm Hg). When blood leaving an arteriole first enters a capillary bed, the CHP is quite high—about 35 mm Hg. Gradually, this initial CHP declines as the blood moves through the capillary so that by the time the blood has reached the venous end, the CHP has dropped to approximately 18 mm Hg. In comparison, the plasma proteins remain suspended in the blood, so the BCOP remains fairly constant at about 25 mm Hg throughout the length of the capillary and considerably below the osmotic pressure in the interstitial fluid. The net filtration pressure (NFP) represents the interaction of the hydrostatic and osmotic pressures, driving fluid out of the capillary. It is equal to the difference between the CHP and the BCOP. Since filtration is, by definition, the movement of fluid out of the capillary, when reabsorption is occurring, the NFP is a negative number. NFP changes at different points in a capillary bed (Figure 20.16). Close to the arterial end of the capillary, it is approximately 10 mm Hg, because the CHP of 35 mm Hg minus the BCOP of 25 mm Hg equals 10 mm Hg. Recall that the hydrostatic and osmotic pressures of the interstitial fluid are essentially negligible. Thus, the NFP of 10 mm Hg drives a net movement of fluid out of the capillary at the arterial end. At approximately the middle of the capillary, the CHP is about the same as the BCOP of 25 mm Hg, so the NFP drops to zero. At this point, there is no net change of volume: Fluid moves out of the capillary at the same rate as it moves into the capillary. Near the venous end of the capillary, the CHP has dwindled to about 18 mm Hg due to loss of fluid. Because the BCOP remains steady at 25 mm Hg, water is drawn into the capillary, that is, reabsorption occurs. Another way of expressing this is to say that at the venous end of the capillary, there is an NFP of −7 mm Hg.
The osmoregulatory system is interconnected with the circulatory system to permit effective regulation of salt and water balance. Circulatory fluids function in renal clearance, which is the blood volume that substances are removed from within the kidneys during a certain time period. In addition to filtration, the circulatory system also plays a role in reabsorption. Furthermore, the role of the renal portal system is to regulate renal hemodynamics during times of decreased arterial blood pressure.Kidneys of common ravens receive arterial and afferent venous blood and are drained by efferent veins.
These secretions can effect the retention of salt and water as well as influencing the intake of salt and water within the kidneys. The renal will allow the receptors to change the longer-term mean pressure.Through the vagal nerve, impulses transmits from the atria to the vagal center of the medulla. This causes a reduction in the sympathetic outflow the kidney, which results in decreased renal blood flow and decreased urine output. This same sympathetic outflow is increased to the sinus node in the atria, which causes increased heart rate/cardiac output. These cardiopulmonary receptors also inhibits vagal stimulation in the vasoconstrictor center of the medulla resulting in decreased release of angiotensin, aldosterone, and vasopressin.
Systemic arteries can be subdivided into two types—muscular and elastic—according to the relative compositions of elastic and muscle tissue in their tunica media as well as their size and the makeup of the internal and external elastic lamina. The larger arteries (>10 mm diameter) are generally elastic and the smaller ones (0.1–10 mm) tend to be muscular. Systemic arteries deliver blood to the arterioles, and then to the capillaries, where nutrients and gases are exchanged. After traveling from the aorta, blood travels through peripheral arteries into smaller arteries called arterioles, and eventually to capillaries. Arterioles help in regulating blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the capillaries.
The pulse pressure is the difference between the measured systolic and diastolic pressures, P pulse = P sys − P dias . {\displaystyle \!P_{\text{pulse}}=P_{\text{sys}}-P_{\text{dias}}.} The pulse pressure is a consequence of the pulsatile nature of the cardiac output, i.e. the heartbeat. The magnitude of the pulse pressure is usually attributed to the interaction of the stroke volume of the heart, the compliance (ability to expand) of the arterial system—largely attributable to the aorta and large elastic arteries—and the resistance to flow in the arterial tree.
In fluid statics, capillary pressure ( p c {\displaystyle {p_{c}}} ) is the pressure between two immiscible fluids in a thin tube (see capillary action), resulting from the interactions of forces between the fluids and solid walls of the tube. Capillary pressure can serve as both an opposing or driving force for fluid transport and is a significant property for research and industrial purposes (namely microfluidic design and oil extraction from porous rock). It is also observed in natural phenomena.
|
What attracts the earth to the sun?
|
[
"weight",
"gravity",
"light",
"the moon"
] |
B
|
The earth is attracted to the sun by the force of gravity. Why doesn’t the earth fall into the sun?.
This results in the emission of electromagnetic radiation across the electromagnetic spectrum. High-energy electromagnetic radiation from solar flares is absorbed by the daylight side of Earth's upper atmosphere, in particular the ionosphere, and does not reach the surface.
Superimposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field.
The atmosphere of Earth also plays an important role. The ozone layer protects the planet from the harmful radiations from the sun, and free oxygen is abundant enough for the breathing needs of terrestrial life. Earth's magnetosphere, generated by its active core, is also important for the long-term habitability of Earth, as it prevents the solar winds from stripping the atmosphere out of the planet.
The Sun has also undergone periodic changes in luminosity that can have a significant impact on the Earth. The Maunder minimum, for example, is believed to have caused the Little Ice Age phenomenon during the Middle Ages.At the center of the Sun is the core region, a volume of sufficient temperature and pressure for nuclear fusion to occur. Above the core is the radiation zone, where the plasma conveys the energy flux by means of radiation.
Deserts lying in low latitudes usually have few clouds and can receive sunshine for more than ten hours a day. These hot deserts form the Global Sun Belt circling the world. This belt consists of extensive swathes of land in Northern Africa, Southern Africa, Southwest Asia, Middle East, and Australia, as well as the much smaller deserts of North and South America.So solar is (or is predicted to become) the cheapest source of energy in all of Central America, Africa, the Middle East, India, South-east Asia, Australia, and several other places. : 8 Different measurements of solar irradiance (direct normal irradiance, global horizontal irradiance) are mapped below:
|
Fermat’s principle states that light will always take the path of least amount of?
|
[
"energy",
"time",
"momentum",
"resistance"
] |
B
|
Fermat’s Principle states that light will always take the path of least amount of time (not distance). This principle governs the paths light will take and explains the familiar phenomena of reflection, refraction, lenses and diffraction. Light rarely travels in a straight-line path. When photons interact with electrons in matter the time it takes for this interaction determines the path. For example, higher frequency blue light is refracted more than red because blue wavelengths interacts more frequently with electrons than red wavelengths and the path of least time is for blue to bend more then red in order to get out of this ‘slow’ area faster. The rainbows we see are a result of this. Fermat’s Principle explains the many fascinating phenomena of light from rainbows to sunsets to the haloes around the moon.
If a ray follows a straight line, it obviously takes the path of least length. Hero of Alexandria, in his Catoptrics (1st century CE), showed that the ordinary law of reflection off a plane surface follows from the premise that the total length of the ray path is a minimum. Ibn al-Haytham, an 11th century polymaths later extended this principle to refraction, hence giving an early version of the Fermat's principle.
"And if this which he has said be conceded, then Aristotle's demonstration will be false; because, if the proportion of the rarity of one medium to the rarity of the other is as the proportion of accidental retardation of the movement in one of them to the retardation occurring to it in the other, and is not as the proportion of the motion itself, it will not follow that what is moved in a void would be moved in an instant; because in that case there would be subtracted from the motion only the retardation affecting it by reason of the medium, and its natural motion would remain. And every motion involves time; therefore what is moved in a void is necessarily moved in time and with a divisible motion; nothing impossible will follow. This, then, is Avempace's question."
The idea is that for a cause at one point to have an effect at another point, something in the space between those points must mediate the action. To exert an influence, something, such as a wave or particle, must travel through the space between the two points, carrying the influence. The special theory of relativity limits the speed at which any such influence can travel to the speed of light, c {\displaystyle c} .
Pál Turán's suggestion that weak coffee was only suitable for lemma. The "turtles all the way down" story told by Stephen Hawking. Fermat's lost simple proof. The unwieldy proof and associated controversies of the Four Color Theorem.
Heinrich Wieleitner (1929) wrote:Fermat replaces A with A+E. Then he sets the new expression roughly equal (angenähert gleich) to the old one, cancels equal terms on both sides, and divides by the highest possible power of E. He then cancels all terms which contain E and sets those that remain equal to each other. From that A results.
|
Many enzymes require nonprotein helpers for what activity?
|
[
"hydrogen",
"kinetic",
"catalytic",
"functional"
] |
C
|
Typically the suffix -ase is added to the name of the substrate (e.g., lactase is the enzyme that cleaves lactose) or the type of reaction (e.g., DNA polymerase forms DNA polymers). Having shown that enzymes could function outside a living cell, the next step was to determine their biochemical nature. Many early workers noted that enzymatic activity was associated with proteins, but several scientists (such as Nobel laureate Richard Willstätter) argued that proteins were merely carriers for the true enzymes and that proteins per se were incapable of catalysis.
There are five main ways that enzyme activity is controlled in the cell. : 30.1.1
In biology, enzymes are protein-based catalysts in metabolism and catabolism. Most biocatalysts are enzymes, but other non-protein-based classes of biomolecules also exhibit catalytic properties including ribozymes, and synthetic deoxyribozymes.Biocatalysts can be thought of as an intermediate between homogeneous and heterogeneous catalysts, although strictly speaking soluble enzymes are homogeneous catalysts and membrane-bound enzymes are heterogeneous. Several factors affect the activity of enzymes (and other catalysts) including temperature, pH, the concentration of enzymes, substrate, and products. A particularly important reagent in enzymatic reactions is water, which is the product of many bond-forming reactions and a reactant in many bond-breaking processes.
Here, the active and inactive form of the enzymes are altered due to covalent modification of their structures which is catalysed by other enzymes. This type of regulation consists of the addition or elimination of some molecules which can be attached to the enzyme protein. The most important groups that work as modifiers are phosphate, methyl, uridine, adenine and adenosine diphosphate ribosyl.
In enzymology, an oligopeptide-transporting ATPase (EC 3.6.3.23) is an enzyme that catalyzes the chemical reaction ATP + H2O + oligopeptide(out) ⇌ {\displaystyle \rightleftharpoons } ADP + phosphate + oligopeptide(in)The 3 substrates of this enzyme are ATP, H2O, and oligopeptide, whereas its 3 products are ADP, phosphate, and oligopeptide. This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides to catalyse transmembrane movement of substances. The systematic name of this enzyme class is ATP phosphohydrolase (oligopeptide-importing). This enzyme is also called oligopeptide permease.
|
What is often a result of untreated atherosclerosis?
|
[
"cancer",
"heart disease",
"a heart attack or stroke",
"seizures"
] |
C
|
Coronary artery disease, also known as ischemic heart disease, is caused by atherosclerosis—a build-up of fatty material along the inner walls of the arteries. These fatty deposits known as atherosclerotic plaques narrow the coronary arteries, and if severe may reduce blood flow to the heart. If a narrowing (or stenosis) is relatively minor then the patient may not experience any symptoms. Severe narrowings may cause chest pain (angina) or breathlessness during exercise or even at rest.
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), stroke, heart failure, hypertensive heart disease, rheumatic heart disease, cardiomyopathy, abnormal heart rhythms, congenital heart disease, valvular heart disease, carditis, aortic aneurysms, peripheral artery disease, thromboembolic disease, and venous thrombosis.The underlying mechanisms vary depending on the disease. It is estimated that dietary risk factors are associated with 53% of CVD deaths. Coronary artery disease, stroke, and peripheral artery disease involve atherosclerosis.
The phenomenon of embolisation of cholesterol was first recognized by the Danish pathologist Dr. Peter Ludvig Panum and published in 1862. Further evidence that eroded atheroma was the source of emboli came from American pathologist Dr. Curtis M. Flory, who in 1945 reported the phenomenon in 3.4% of a large autopsy series of older individuals with severe atherosclerosis of the aorta.
Lumen stenosis that is greater than 75% was considered the hallmark of clinically significant disease in the past because recurring episodes of angina and abnormalities in stress tests are only detectable at that particular severity of stenosis. However, clinical trials have shown that only about 14% of clinically debilitating events occur at sites with more than 75% stenosis. The majority of cardiovascular events that involve sudden rupture of the atheroma plaque do not display any evident narrowing of the lumen.
The disease typically presents with joint pain, high fevers, a salmon-pink macular or maculopapular rash, enlargement of the liver and spleen, swollen lymph nodes, and a neutrophil-predominant increased white blood cell count in the blood. Tests for rheumatoid factor and anti-nuclear antibodies are usually negative and serum ferritin is markedly elevated. Patients experiencing a flare-up from adult-onset Still's disease usually report extreme fatigue, swelling of the lymph nodes and, less commonly, fluid accumulation in the lungs and heart. In rare cases, AOSD can cause life-threatening complications, including hemophagocytic lymphohistiocytosis, IVDC, fulminant hepatitis, or disabling conditions such as aseptic meningitis and sensorineural hearing loss.
|
The hormones epinephrine and norepinephrine are released by what?
|
[
"uptake medulla",
"nutrients medulla",
"external medulla",
"adrenal medulla"
] |
D
|
Short-term Stress Response When presented with a stressful situation, the body responds by calling for the release of hormones that provide a burst of energy. The hormones epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline) are released by the adrenal medulla. How do these hormones provide a burst of energy? Epinephrine and norepinephrine increase blood glucose levels by stimulating the liver and skeletal muscles to break down glycogen and by stimulating glucose release by liver cells. Additionally, these hormones increase oxygen availability to cells by increasing the heart rate and dilating the bronchioles. The hormones also prioritize body function by increasing blood supply to essential organs such as the heart, brain, and skeletal muscles, while restricting blood flow to organs not in immediate need, such as the skin, digestive system, and kidneys. Epinephrine and norepinephrine are collectively called catecholamines.
Rather than releasing a neurotransmitter, the cells of the adrenal medulla secrete hormones.The adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines; epinephrine, norepinephrine, and dopamine. Because the ANS, specifically the sympathetic division, exerts direct control over the chromaffin cells, the hormone release can occur rather quickly. In response to stressors, such as exercise or imminent danger, medullary cells release the catecholamines adrenaline and noradrenaline into the blood. Adrenaline composes about 85% of the released catecholamines, and noradrenaline the other 15%.Notable effects of adrenaline (epinephrine) and noradrenaline (norepinephrine) include increased heart rate and blood pressure, blood vessel constriction in the skin and gastrointestinal tract, smooth muscle (bronchiole and capillary) dilation, and increased metabolism, all of which are characteristic of the fight-or-flight response. Release of catecholamines is stimulated by nerve impulses, and receptors for catecholamines are widely distributed throughout the body.
In the case of steroid hormone receptors, their stimulation leads to binding to the promoter region of steroid-responsive genes.Not all classifications of signaling molecules take into account the molecular nature of each class member. For example, odorants belong to a wide range of molecular classes, as do neurotransmitters, which range in size from small molecules such as dopamine to neuropeptides such as endorphins. Moreover, some molecules may fit into more than one class, e.g. epinephrine is a neurotransmitter when secreted by the central nervous system and a hormone when secreted by the adrenal medulla.
Norepinephrine interacts with postsynaptic α and β adrenergic receptor subtypes and presynaptic α2 autoreceptors. The α2 receptors include presynaptic autoreceptors which limit the neurophysiological activity of noradrenergic neurons in the central nervous system. Formation of norepinephrine is reduced by autoreceptors through the rate-limiting enzyme tyrosine hydroxylase, an effect mediated by decreased cyclic AMP-mediated phosphorylation-activation of the enzyme.
Norepinephrine is the main neurotransmitter used by the sympathetic nervous system, which consists of about two dozen sympathetic chain ganglia located next to the spinal cord, plus a set of prevertebral ganglia located in the chest and abdomen. These sympathetic ganglia are connected to numerous organs, including the eyes, salivary glands, heart, lungs, liver, gallbladder, stomach, intestines, kidneys, urinary bladder, reproductive organs, muscles, skin, and adrenal glands. Sympathetic activation of the adrenal glands causes the part called the adrenal medulla to release norepinephrine (as well as epinephrine) into the bloodstream, from which, functioning as a hormone, it gains further access to a wide variety of tissues.Broadly speaking, the effect of norepinephrine on each target organ is to modify its state in a way that makes it more conducive to active body movement, often at a cost of increased energy use and increased wear and tear. This can be contrasted with the acetylcholine-mediated effects of the parasympathetic nervous system, which modifies most of the same organs into a state more conducive to rest, recovery, and digestion of food, and usually less costly in terms of energy expenditure.The sympathetic effects of norepinephrine include: In the eyes, an increase in production of tears, making the eyes more moist, and pupil dilation through contraction of the iris dilator.
AtropineComplementary: Epinephrine (adrenaline)α
|
How many possible alleles do the majority of human genes have?
|
[
"three or more",
"two or less",
"less than four",
"two or more"
] |
D
|
The majority of human genes have two or more possible alleles. Differences in alleles account for the considerable genetic variation among people. In fact, most human genetic variation is the result of differences in individual DNA bases within alleles.
Normally humans have 2 copies of chromosome 16, one inherited by each parent. This chromosome represents almost 3% of all DNA in cells.
In diploid organisms (like humans), the somatic cells possess two copies of the genome, one inherited from the father and one from the mother. Each autosomal gene is therefore represented by two copies, or alleles, with one copy inherited from each parent at fertilization. The expressed allele is dependent upon its parental origin. For example, the gene encoding insulin-like growth factor 2 (IGF2/Igf2) is only expressed from the allele inherited from the father.
"Within a population, SNPs can be assigned a minor allele frequency—the lowest allele frequency at a locus that is observed in a particular population. This is simply the lesser of the two allele frequencies for single-nucleotide polymorphisms. With this knowledge scientists have developed new methods in analyzing population structures in less studied species.
On the other hand, the greater the number of traits (or alleles) considered, the more subdivisions of humanity are detected, since traits and gene frequencies do not always correspond to the same geographical location. Or as Ossorio & Duster (2005) put it:Anthropologists long ago discovered that humans' physical traits vary gradually, with groups that are close geographic neighbors being more similar than groups that are geographically separated. This pattern of variation, known as clinal variation, is also observed for many alleles that vary from one human group to another.
Since it can never more than double in frequency with each generation, a gene drive introduced in a single individual typically requires dozens of generations to affect a substantial fraction of a population. Alternatively, releasing drive-containing organisms in sufficient numbers can affect the rest within a few generations; for instance, by introducing it in every thousandth individual, it takes only 12–15 generations to be present in all individuals. Whether a gene drive will ultimately become fixed in a population and at which speed depends on its effect on individual fitness, on the rate of allele conversion, and on the population structure. In a well mixed population and with realistic allele conversion frequencies (≈90%), population genetics predicts that gene drives get fixed for a selection coefficient smaller than 0.3; in other words, gene drives can be used to spread modifications as long as reproductive success is not reduced by more than 30%. This is in contrast with normal genes, which can only spread across large populations if they increase fitness.
|
What occurs during the new moon and full moon, due to gravitational pull?
|
[
"spring waves",
"spring floods",
"spring storms",
"spring tides"
] |
D
|
Spring tides occur during the new moon and full moon. The Sun and Moon must either be in a straight line on the same side of Earth, or they must be on opposite sides of Earth. Their gravitational pull combines to cause very high and very low tides. Spring tides have the greatest tidal range.
A large portion of the mare formed, or flowed into, the low elevations associated with the nearside impact basins. However, Oceanus Procellarum does not correspond to any known impact structure, and the lowest elevations of the Moon within the farside South Pole-Aitken basin are only modestly covered by mare (see lunar mare for a more detailed discussion). Impacts by meteorites and comets are the only abrupt geologic force acting on the Moon today, though the variation of Earth tides on the scale of the Lunar anomalistic month causes small variations in stresses.
A natural outcome of the hypothetical giant-impact event is that the materials that re-accreted to form the Moon must have been hot. Current models predict that a large portion of the Moon would have been molten shortly after the Moon formed, with estimates for the depth of this magma ocean ranging from about 500 km to complete melting. Crystallization of this magma ocean would have given rise to a differentiated body with a compositionally distinct crust and mantle and accounts for the major suites of lunar rocks.
Atmospheric tides are also produced through the gravitational effects of the Moon. Lunar (gravitational) tides are much weaker than solar thermal tides and are generated by the motion of the Earth's oceans (caused by the Moon) and to a lesser extent the effect of the Moon's gravitational attraction on the atmosphere.
The former acted over the moon's entire history and influenced all surfaces. The latter processes were also global in nature, but active mainly for a period following the moon's formation. They obliterated the original heavily cratered terrain, explaining the relatively low number of impact craters on the moon's present-day surface.
Most natural satellites of the planets undergo tidal acceleration to some degree (usually small), except for the two classes of tidally decelerated bodies. In most cases, however, the effect is small enough that even after billions of years most satellites will not actually be lost. The effect is probably most pronounced for Mars's second moon Deimos, which may become an Earth-crossing asteroid after it leaks out of Mars's grip. The effect also arises between different components in a binary star.
|
Alleles that carry deadly diseases are usually which type?
|
[
"recessive",
"dominant",
"predominant",
"inherited"
] |
A
|
This category is for variants that are not causative for a disease.
Penetrance in genetics is the proportion of individuals carrying a particular variant (or allele) of a gene (the genotype) that also expresses an associated trait (the phenotype). In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation that exhibit clinical symptoms among all individuals with such mutation. For example, if a mutation in the gene responsible for a particular autosomal dominant disorder has 95% penetrance, then 95% of those with the mutation will develop the disease, while 5% will not. A condition, most commonly inherited in an autosomal dominant manner, is said to show complete penetrance if clinical symptoms are present in all individuals who have the disease-causing mutation.
Common diseases in this category include whooping cough or tuberculosis, HIV/AIDs, malaria, influenza (the flu), and mumps. As low-to-middle income countries continue to develop, the types of diseases that affecting populations within these countries shifts primarily from infectious diseases, such as diarrhea and pneumonia, to primarily non-communicable diseases, such as cardiovascular disease, cancer and obesity. This shift is increasingly being referred to as the risk transition.
Regarding patient treatment, only the phenotype is usually of any clinical significance to ensure a patient is not exposed to an antigen they are likely to develop antibodies against. A probable genotype may be speculated on, based upon the statistical distributions of genotypes in the patient's place of origin.R0 (cDe or Dce) is today most common in Africa. The allele was thus often assumed in early blood group analyses to have been typical of populations on the continent; particularly in areas below the Sahara.
For example, certain combinations of the DLA-DRB1 and DQ alleles are most favorable for good immune regulation. These alleles help balance immune surveillance and immune response without increasing the risk of developing an autoimmune condition.
|
What releases fatty acids and other components from fats and phospholipids?
|
[
"metabolism",
"enzyme respiration",
"peristaltic hydrolysis",
"enzymatic hydrolysis"
] |
D
|
Fatty acids are an integral part of the phospholipids that make up the bulk of the plasma membranes, or cell membranes, of cells. These phospholipids can be cleaved into diacylglycerol (DAG) and inositol trisphosphate (IP3) through hydrolysis of the phospholipid, phosphatidylinositol 4,5-bisphosphate (PIP2), by the cell membrane bound enzyme phospholipase C (PLC).
Fats are broken down in the healthy body to release their constituents, glycerol and fatty acids. Glycerol itself can be converted to glucose by the liver and so become a source of energy. Fats and other lipids are broken down in the body by enzymes called lipases produced in the pancreas.
Fatty acyl chains delivered by this route can then be acylated into tissue membrane phospholipids. Lysophosphatidylcholine processing has been discovered to be an essential component of normal human brain development: those born with genes that prevent adequate uptake suffer from lethal microcephaly. MFSD2a has been shown to transport LPC-bound polyunsaturated fatty acids, including DHA and EPA, across the blood-brain and blood-retinal barriers.
Phosphatidic acids are anionic phospholipids important to cell signaling and direct activation of lipid-gated ion channels. Hydrolysis of phosphatidic acid gives rise to one molecule each of glycerol and phosphoric acid and two molecules of fatty acids. They constitute about 0.25% of phospholipids in the bilayer.
Synthesis of diacylglycerol begins with glycerol-3-phosphate, which is derived primarily from dihydroxyacetone phosphate, a product of glycolysis (usually in the cytoplasm of liver or adipose tissue cells). Glycerol-3-phosphate is first acylated with acyl-coenzyme A (acyl-CoA) to form lysophosphatidic acid, which is then acylated with another molecule of acyl-CoA to yield phosphatidic acid. Phosphatidic acid is then de-phosphorylated to form diacylglycerol. Dietary fat is mainly composed of triglycerides.
|
What kind of energy comes from the position of a charged particle in an electric field?
|
[
"potential energy",
"solar energy",
"mechanical energy",
"thermal energy"
] |
A
|
Electric potential energy comes from the position of a charged particle in an electric field. For example, when two negative charges are close together, they have potential energy because they repel each other and have the potential to push apart. If the charges actually move apart, their potential energy decreases. Electric charges always move spontaneously from a position where they have higher potential energy to a position where they have lower potential energy. This is like water falling over a dam from an area of higher to lower potential energy due to gravity.
For instance, the electric field is another rank-1 tensor field, while electrodynamics can be formulated in terms of two interacting vector fields at each point in spacetime, or as a single-rank 2-tensor field.In the modern framework of the quantum theory of fields, even without referring to a test particle, a field occupies space, contains energy, and its presence precludes a classical "true vacuum". This has led physicists to consider electromagnetic fields to be a physical entity, making the field concept a supporting paradigm of the edifice of modern physics. "The fact that the electromagnetic field can possess momentum and energy makes it very real ... a particle makes a field, and a field acts on another particle, and the field has such familiar properties as energy content and momentum, just as particles can have."
In electrodynamics, the force on a charged particle of charge q is the Lorentz force: Combining with Newton's second law gives a first order differential equation of motion, in terms of position of the particle: or its momentum: The same equation can be obtained using the Lagrangian (and applying Lagrange's equations above) for a charged particle of mass m and charge q: where A and ϕ are the electromagnetic scalar and vector potential fields. The Lagrangian indicates an additional detail: the canonical momentum in Lagrangian mechanics is given by: instead of just mv, implying the motion of a charged particle is fundamentally determined by the mass and charge of the particle. The Lagrangian expression was first used to derive the force equation. Alternatively the Hamiltonian (and substituting into the equations): can derive the Lorentz force equation.
The concept of the electric field was introduced by Michael Faraday. An electric field is created by a charged body in the space that surrounds it, and results in a force exerted on any other charges placed within the field. The electric field acts between two charges in a similar manner to the way that the gravitational field acts between two masses, and like it, extends towards infinity and shows an inverse square relationship with distance. However, there is an important difference.
A free particle can be represented by a mass term, and a kinetic term which relates to the "motion" of the fields.
When a charged particle is placed in an electromagnetic field it experiences a force given by the Lorentz force law: F → = q E → + q v → × B → {\displaystyle {\vec {F}}=q{\vec {E}}+q{\vec {v}}\times {\vec {B}}} (in SI units) where q {\displaystyle q} is the charge on the particle, E → {\displaystyle {\vec {E}}} is the electric field, v → {\displaystyle {\vec {v}}} is the particle velocity, and B → {\displaystyle {\vec {B}}} is the magnetic field. The cross product in the magnetic field term means that static magnetic fields cannot be used for particle acceleration, as the magnetic force acts perpendicularly to the direction of particle motion.As electrostatic breakdown limits the maximum constant voltage which can be applied across a gap to produce an electric field, most accelerators use some form of radiofrequency (RF) acceleration. In RF acceleration, the particle traverses a series of accelerating regions, driven by a source of voltage in such a way that the particle sees an accelerating field as it crosses each region. In this type of acceleration, particles must necessarily travel in "bunches" corresponding to the portion of the oscillator's cycle where the electric field is pointing in the intended direction of acceleration.If a single oscillating voltage source is used to drive a series of gaps, those gaps must be placed increasingly far apart as the speed of the particle increases.
|
What does interstellar medium consist of?
|
[
"gravitational waves",
"the strong force",
"dark matter",
"thinly spread gas and dust"
] |
D
|
Space may seem empty, but actually it contains thinly spread gas and dust, called interstellar medium, that gradually collapses over immense stretches of time and collects into denser clouds of gas and dust. The atoms of gas are mostly hydrogen and are typically about a centimeter apart. The dust is mostly carbon and silicon. In some places, this interstellar medium is collected into particularly dense clouds of gas and dust known as a nebula . A nebula is the birthplace of stars. Our sun was probably born in a nebula around 5 billion years ago.
The interstellar medium is matter that occupies the space between star systems in a galaxy. 99% of this matter is gaseous – hydrogen, helium, and smaller quantities of other ionized elements such as oxygen. The other 1% is dust particles, thought to be mainly graphite, silicates, and ices. Clouds of the dust and gas are referred to as nebulae.
Spiral galaxies like the Milky Way contain stars, stellar remnants, and a diffuse interstellar medium (ISM) of gas and dust. The interstellar medium consists of 104 to 106 particles per cm3, and is typically composed of roughly 70% hydrogen, 28% helium, and 1.5% heavier elements by mass. The trace amounts of heavier elements were and are produced within stars via stellar nucleosynthesis and ejected as the stars pass beyond the end of their main sequence lifetime. Higher density regions of the interstellar medium form clouds, or diffuse nebulae, where star formation takes place.
The density of matter in the interstellar medium can vary considerably: the average is around 106 particles per m3, but cold molecular clouds can hold 108–1012 per m3.A number of molecules exist in interstellar space, as can tiny 0.1 μm dust particles. The tally of molecules discovered through radio astronomy is steadily increasing at the rate of about four new species per year.
The inner disk has a radius approximately four times the distance between the sun and the Earth, with a density of around 100,000 times that of the dust in the Solar System.The spectra taken by 2020 have indicated the circumstellar disc is similar in composition to interstellar medium. The dominant species in atomic numbers are hydrogen, helium, oxygen, nitrogen, silicon and iron. Surprisingly, the disk was found to be strongly depleted of carbon and carbon monoxide. == References ==
This is in contrast to the so-called superior planets, such as Mars, which appear to move independently of the Sun. infrared astronomy The subfield of astronomy that studies astronomical objects detectable at infrared wavelengths. International Astronomical Union (IAU) interstellar medium (ISM) The matter that exists in the space between the stars in a galaxy.
|
Sickle-cell disease significantly impairs the function of what?
|
[
"circulatory system",
"limbic system",
"nervous system",
"metabolism system"
] |
A
|
As a recessive gene, Sickle-cell disease is only present if homozygous, with no dominant gene to beat them out. Sickle-cell disease, originating in people living in tropical areas where malaria is prevalent, is a hereditary blood disorder characterized by rigid, sickle-shaped red blood cells.. The unusual shape and rigidity of these altered red blood cells reduces a cell's ability to effectively travel with regular blood flow, occasionally blocking veins and preventing proper blood flow. Life expectancy is shortened for people with sickle-cell disease, though modern medicine has significantly lengthened the life expectancy of someone with this disease. As detrimental the effects of sickle-cell disease seem, it also offers an unforeseen benefit; humans with the sickle-cell gene show less severe symptoms when infected with malaria, as the abnormal shape of blood cells caused by the disease hinder the malaria parasite's ability to invade and replicate within these cells.
The mutated hemoglobin forms polymers and clumps together causing the deoxygenated sickle red blood cells to assume the disfigured sickle shape. As a result, the cells are inflexible and cannot easily flow through blood vessels, increasing the risk of blood clots and possibly depriving vital organs of oxygen. Some complications associated with sickle cell anemia include pain, damaged organs, strokes, high blood pressure, and loss of vision. Sickle red blood cells also have a shortened lifespan and die prematurely.
The pathogen that causes the disease spends part of its cycle in the red blood cells and triggers an abnormal drop in oxygen levels in the cell. In carriers, this drop is sufficient to trigger the full sickle-cell reaction, which leads to infected cells being rapidly removed from circulation and strongly limiting the infection's progress. These individuals have a great resistance to infection and have a greater chance of surviving outbreaks.
Sickle cell anaemia can lead to various complications, including: Increased risk of severe bacterial infections is due to loss of functioning spleen tissue (and comparable to the risk of infections after having the spleen removed surgically). These infections are typically caused by encapsulated organisms such as Streptococcus pneumoniae and Haemophilus influenzae. Daily penicillin prophylaxis is the most commonly used treatment during childhood, with some haematologists continuing treatment indefinitely.
"Sickle Cell Anemia, a Molecular Disease" is a 1949 scientific paper by Linus Pauling, Harvey A. Itano, Seymour J. Singer and Ibert C. Wells that established sickle-cell anemia as a genetic disease in which affected individuals have a different form of the metalloprotein hemoglobin in their blood. The paper, published in the November 25, 1949 issue of Science, reports a difference in electrophoretic mobility between hemoglobin from healthy individuals and those with sickle-cell anemia, with those with sickle cell trait having a mixture of the two types. The paper suggests that the difference in electrophoretic mobility is probably due to a different number of ionizable amino acid residues in the protein portion of hemoglobin (which was confirmed in 1956 by Vernon Ingram), and that this change in molecular structure is responsible for the sickling process.
|
What is the enlarged tip of the penis called?
|
[
"angles penis",
"testicular point",
"outer penis",
"glans penis"
] |
D
|
The penis is an external genital organ with a long shaft and enlarged tip called the glans penis. The shaft of the penis contains erectile tissues that can fill with blood and cause an erection. When this occurs, the penis gets bigger and stiffer. The urethra passes through the penis. Sperm pass out of the body through the urethra. (During urination, the urethra carries urine from the bladder. ).
Penis enlargement, or male enhancement, is any technique aimed to increase the size of a human penis. Some methods aim to increase total length, others the shaft's girth, and yet others the glans size. Techniques include surgery, supplements, ointments, patches, and physical methods like pumping, jelqing, and traction. Surgical penis enlargement methods can be effective; however, such methods carry risks of complications and are not medically indicated except in cases involving a micropenis.
The subcutaneous tissue of penis (or superficial penile fascia) is continuous above with the fascia of Scarpa, and below with the dartos tunic of the scrotum and the fascia of Colles. It is sometimes just called the "dartos layer".It attaches at the intersection of the body and glans.The term "superficial penile fascia" is more common, but "subcutaneous tissue of penis" is the term used by Terminologia Anatomica.
The retracted penis curves in an S-shaped loop and stays inside the body. When erect, it peeks out of the genital slit.
Median raphe cysts are a cutaneous condition of the penis due to developmental defects near the glans. : 682
Stallions (male horses) have a vascular penis. When non-erect, it is quite flaccid and contained within the prepuce (foreskin, or sheath). Tapirs have exceptionally long penises relative to their body size. The glans of the Malayan tapir resembles a mushroom, and is similar to the glans of the horse. The penis of the Sumatran rhinoceros contains two lateral lobes and a structure called the processus glandis.
|
What do you call the point at which the entire weight of a body may be considered to be concentrated?
|
[
"center of gravity",
"center of earth",
"complex of gravity",
"direction of gravity"
] |
A
|
Every object has a center of gravity . The center of gravity is the point at which the entire weight of a body may be considered to be concentrated; if supported at this point, the body would remain in equilibrium in any position. For example, if we were discussing a 12-inch ruler, the center of gravity for the ruler would be at the center of the 6-inch line. You could put your finger directly under the 6-inch line to hold the ruler and it would not fall either left or right. If you placed your finger underneath any other place on the ruler, it would fall off to one side or the other.
In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight. Mass moment of inertiaThe moment of inertia, otherwise known as the mass moment of inertia, angular mass, second moment of mass, or most accurately, rotational inertia, of a rigid body is a quantity that determines the torque needed for a desired angular acceleration about a rotational axis, akin to how mass determines the force needed for a desired acceleration. It depends on the body's mass distribution and the axis chosen, with larger moments requiring more torque to change the body's rate of rotation.
In the case of above, the animal now has eight times the biologically active tissue to support, but the surface area of its respiratory organs has only increased fourfold, creating a mismatch between scaling and physical demands. Similarly, the organism in the above example now has eight times the mass to support on its legs, but the strength of its bones and muscles is dependent upon their cross-sectional area, which has only increased fourfold. Therefore, this hypothetical organism would experience twice the bone and muscle loads of its smaller version. This mismatch can be avoided either by being "overbuilt" when small or by changing proportions during growth, called allometry. Isometric scaling is often used as a null hypothesis in scaling studies, with 'deviations from isometry' considered evidence of physiological factors forcing allometric growth.
The apothecaries' system, or apothecaries' weights and measures, is a historical system of mass and volume units that were used by physicians and apothecaries for medical prescriptions and also sometimes by scientists. The English version of the system is closely related to the English troy system of weights, the pound and grain being exactly the same in both. It divides a pound into 12 ounces, an ounce into 8 drachms, and a drachm into 3 scruples of 20 grains each. This exact form of the system was used in the United Kingdom; in some of its former colonies, it survived well into the 20th century.
The standard atomic weight (commonly called "atomic weight") of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance, relative to the atomic mass unit. This number may be a fraction that is not close to a whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element.
The molar volume of a substance i is defined as its molar mass divided by its density ρi0: For an ideal mixture containing N components, the molar volume of the mixture is the weighted sum of the molar volumes of its individual components. For a real mixture the molar volume cannot be calculated without knowing the density: There are many liquid–liquid mixtures, for instance mixing pure ethanol and pure water, which may experience contraction or expansion upon mixing. This effect is represented by the quantity excess volume of the mixture, an example of excess property.
|
At how many places does points source pollution enter water?
|
[
"one",
"three",
"two",
"four"
] |
A
|
Point source pollution enters water at just one place. For example, it might enter a stream through a pipe. Non-point source pollution enters water everywhere. It is carried by runoff.
Controlling nonpoint source pollution requires improving the management of urban and suburban areas, agricultural operations, forestry operations and marinas. Types of nonpoint source water pollution include sediment, nutrients, toxic contaminants and chemicals and pathogens. Principal sources of nonpoint source water pollution include: urban and suburban areas, agricultural operations, atmospheric inputs, highway runoff, forestry and mining operations, marinas and boating activities.
Rivers and streams drain water that falls on upland areas, and this moving water dissolves pollutants at a faster rate than standing water. However, due to the high production and placement of pollutants in these moving waters, the waters become polluted faster than the pollutant dilution rate, leading to over polluted rivers and streams. All three of the major contributors to pollution – industry, agriculture, and cities – are commonly found along moving waters, adding to the over-pollution of rivers and streams. Just the knowledge that fast moving waters can dilute pollutants has encouraged even more pollution, further adding to the pollution issue.
However, in the 21st century, mercury is still entering many water bodies through atmospheric deposition, mainly from combustion of coal. Point source regulatory programPoint source discharges require permits under the National Pollutant Discharge Elimination System (NPDES).
A comprehensive water point mapping exercise (28,845 water points) in 2012 showed the rate of damage of public water points is high and rises rapidly with point age: 14.4% were functional but partly damaged, and 17.8% are broken down. Furthermore, up to 40% of protected in-use points providing insufficient water during the dry season. A 2010 survey of all existing water access points across three districts (2,859 structures) found only 30% of the structures in place were found to be capable of delivering access to safe water throughout the year.
Owing to drainage of surface and groundwater in the project area, which waters may be salinized and polluted by agricultural chemicals like biocides and fertilizers, the quality of the river water below the project area can deteriorate, which makes it less fit for industrial, municipal and household use. It may lead to reduced public health. Polluted river water entering the sea may adversely affect the ecology along the seashore (see Aswan dam). The natural contribution of sediments can be eliminated by the detention of sediments behind the dams critical to surface water irrigation diversions.
|
What do monarch butterfly larvae depend on for their food?
|
[
"seaweed",
"pollen",
"milkweeds",
"honey"
] |
C
|
Another concern about biotechnology is how it may affect the environment. Negative effects on the environment have already occurred because of some GMOs. For example, corn has been created that has a gene for a pesticide. The corn plants have accidentally cross-pollinated nearby milkweeds. Monarch butterfly larvae depend on milkweeds for food. When they eat milkweeds with the pesticide gene, they are poisoned. This may threaten the survival of the monarch species as well as other species that eat monarchs. Do the benefits of the genetically modified corn outweigh the risks? What do you think?.
While the larvae are dependent on the host plants, mostly the dwarf plantain, for sustenance the adult butterflies live on nectar. They feed on a variety of plants associated with serpentine grasslands. Some of these plants include California goldfields, white turtlehead, desert parsley, scytheleaf onion, false babystars, intermediate fiddleneck and others. Female fecundity is dramatically affected by nectar availability.
Climate variations during the fall and summer affect butterfly reproduction. Rainfall and freezing temperatures affect milkweed growth. Omar Vidal, director general of WWF-Mexico, said, "The monarch's lifecycle depends on the climatic conditions in the places where they breed.
This species is predatory and typically eats live insects, but they also feed on the flesh of deceased prey. They typically prey on arthropods, including spiders and caterpillars. For larvae to grow into the pupal state, adult workers find prey and bring food back for them. When establishing the colony, the queen goes out in search of nectar and insects for the larvae, as well. This species does not produce honey, though.
The larval stage, or caterpillar, is characterized by a pinkish or yellowish-green body color with a dark brown head. The larval stage of the moth's life cycle is centered on food sources; during the last instar, these larvae are characterized by a movement towards a protected area to pupate. These caterpillars have the capacity to chew through plastic packaging and will often produce silk that loosely binds to food fragments. The pupal stage is generally observed as tiny cocoons that hang from the ceiling; these cocoons can also be found on walls, as well as near the food source. A female can lay over 200 eggs and will usually die after this process because adults Indianmeal moths do not eat.
When searching for nectar, color is the first cue that draws the insect's attention toward a potential food source, and shape is a secondary characteristic that promotes the process. When searching for a place to lay its eggs, the roles of color and shape are switched. Also, a difference may exist between male and female butterflies from other species in terms of the ability to learn certain colors; however, no differences are noted between the sexes for monarch butterflies.
|
As lava cools, tiny iron-rich crystals line up with earth’s what?
|
[
"gravitational field",
"oceans",
"magnetic field",
"molecular field"
] |
C
|
Some rocks contain little compasses too! As lava cools, tiny iron-rich crystals line up with Earth’s magnetic field. Anywhere lavas have cooled, these magnetite crystals point to the magnetic poles. The little magnets point to where the north pole was when the lava cooled. Scientists can use this to figure out where the continents were at that time. This evidence clearly shows that the continents have moved.
Depending on the amount of sulfur in the core, the core has a radius between 350 and 650 km (220–400 mi) if it is composed almost entirely of iron, or between 550 and 900 km (340–560 mi) for a core consisting of a mix of iron and sulfur. Galileo's magnetometer failed to detect an internal, intrinsic magnetic field at Io, suggesting that the core is not convecting.Modeling of Io's interior composition suggests that the mantle is composed of at least 75% of the magnesium-rich mineral forsterite, and has a bulk composition similar to that of L-chondrite and LL-chondrite meteorites, with higher iron content (compared to silicon) than the Moon or Earth, but lower than Mars. To support the heat flow observed on Io, 10–20% of Io's mantle may be molten, though regions where high-temperature volcanism has been observed may have higher melt fractions.
Near subduction zones, partial melting of the subducting plate within the asthenosphere (80 to 200 km depth) produces a volatile-rich magma (high concentrations of CO2 and water), with high concentrations of alkaline elements, and high element mobility that the rare earths are strongly partitioned into. This melt may also rise along pre-existing fractures, and be emplaced in the crust above the subducting slab or erupted at the surface. REE-enriched deposits forming from these melts are typically S-Type granitoids.Alkaline magmas enriched with rare-earth elements include carbonatites, peralkaline granites (pegmatites), and nepheline syenite.
The Earth's crustal rock is composed in large part of oxides of silicon (silica SiO2, as found in granite and quartz), aluminium (aluminium oxide Al2O3, in bauxite and corundum), iron (iron(III) oxide Fe2O3, in hematite and rust), and calcium carbonate (in limestone). The rest of the Earth's crust is also made of oxygen compounds, in particular various complex silicates (in silicate minerals). The Earth's mantle, of much larger mass than the crust, is largely composed of silicates of magnesium and iron.
The sub-family of rocks that form from volcanic lava are called igneous volcanic rocks (to differentiate them from igneous rocks that form from magma below the surface, called igneous plutonic rocks). The lavas of different volcanoes, when cooled and hardened, differ much in their appearance and composition. If a rhyolite lava-stream cools quickly, it can quickly freeze into a black glassy substance called obsidian.
Experiments suggest that viscosity of the magma ocean was low, thereby implying turbulent convective flow that rapidly dissipates heat. If true, the magma ocean can only have existed for a few thousands years.Iron droplets in the magma ocean existed in a variety of sizes depending on the size of the bodies impacting the Earth. In molten state large bodies tend to break, whereas small bodies tend to coalesce. The equilibrium is found by the Weber number that provides a mean to calculate the stabilized diameter of the liquid iron droplets, which corresponds to 10 cm. After iron droplets form they segregate from the surrounding silicates and precipitate in a "rain".
|
What do we call the amount of time a substance is stored in a reservoir?
|
[
"storage time",
"latency",
"presence time",
"residence time"
] |
D
|
A substance is stored in a reservoir. The amount of time it stays in that reservoir is its residence time.
Aside from chemical requirements several key factors influence extraction efficiency: Retention time - refers to the time spent in the leaching system by the solids. This is calculated as the total volumetric capacity of the leach tank/s divided by the volumetric throughput of the solid/liquid slurry. Retention time is commonly measured in hours for precious metals recovery. A sequence of leach tanks is referred to as a leach "train", and retention time is measured considering the total volume of the leach train.
It can be represented by an IF-statement in the software code, and it occurs in some commercial reservoir simulators. The process (or rather sequence of processes) may be due to a backup plan for field recovery, or the injected fluid may flow to another reservoir rock formation due to an unexpected open part of a fault or a non-sealing cement behind casing of the injection well. The option for relative permeability is seldom used, and we just note that it does not change (the analytical shape of) the governing equation, but increases (usually doubles) the number of constitutive equations for the properties involved.
Contrary to the linear reservoir, the non linear reservoir has a reaction factor A that is not a constant, but it is a function of S or Q (figure 2, 3). Normally A increases with Q and S because the higher the water level is the higher the discharge capacity becomes. The factor is therefore called Aq instead of A. The non-linear reservoir has no usable unit hydrograph.
Water residence times influence nutrient and carbon processing rates. Longer residence times promote dissolved solute retention, which can be later released back into the channel, delaying or attenuating the signals produced by the stream channel.The other key concept is that of hyporheic exchange, or the speed at which water enters or leaves the subsurface zone.
The limnology of reservoirs has many similarities to that of lakes of equivalent size. There are however significant differences. Many reservoirs experience considerable variations in level producing significant areas that are intermittently underwater or dried out.
|
Osmotic pressure is important in biological systems because cell walls are what?
|
[
"impassable",
"theonym membranes",
"semipermeable membranes",
"variably membranes"
] |
C
|
Osmotic pressure is important in biological systems because cell walls are semipermeable membranes. In particular, when a person is receiving intravenous (IV) fluids, the osmotic pressure of the fluid needs to be approximately the same as blood serum; otherwise bad things can happen. Figure 11.4 "Osmotic Pressure and Red Blood Cells" shows three red blood cells: Figure 11.4 "Osmotic Pressure and Red Blood Cells"a shows a healthy red blood cell. Figure 11.4 "Osmotic Pressure and Red Blood Cells"b shows a red blood cell that has been exposed to a lower concentration than normal blood serum (a socalled hypotonic solution); the cell has plumped up as solvent moves into the cell to dilute the solutes inside. Figure 11.4 "Osmotic Pressure and Red Blood Cells"c shows a red blood cell exposed to a higher concentration than normal blood serum (hypertonic); water leaves the red blood cell, so it collapses onto itself. Only when the solutions inside and outside the cell are the same (isotonic) will the red blood cell be able to do its job.
Cells that have a cell wall tend to be more resistant to osmotic shock because their cell wall enables them to maintain their shape. Although single-celled organisms are more vulnerable to osmotic shock, since they are directly exposed to their environment, cells in large animals such as mammals still suffer these stresses under some conditions. Current research also suggests that osmotic stress in cells and tissues may significantly contribute to many human diseases.In eukaryotes, calcium acts as one of the primary regulators of osmotic stress. Intracellular calcium levels rise during hypo-osmotic and hyper-osmotic stresses.
Application of a ramp of negative pressure to a patch excised from an E. coli giant spheroplast gave a small conductance (MscS; ~1 nS in 400 mM salt) with a sustained open state, and a large conductance (MscL; ~3 nS) with faster kinetics, activated at higher pressure. MscS was reported to exhibit a weak anionic preference and a voltage dependency, tending to open upon depolarization. Activation by membrane-intercalating amphipathic compounds suggested that the MscS channel is sensitive to mechanical perturbations in the lipid bilayer.Sensitivity towards tension changes can be explained as result of the hydrophobic coupling between the membrane and TMSs of the channel.
Osmotic blistering is a chemical phenomenon where two substances attempt to reach equilibrium through a semi-permeable membrane.
Negative pressure is used to move the nucleus near the pipette tip while moving the electrode near the center of the soma. The model system in question will affect the negative pressure to be applied. In human and non-human primates cell viability is more difficult to ensure. Larger variations in neuronal size compared to rodent models means greater variability in the amount of negative pressure needed to be applied to extract the cytosol and nucleus.
Chemotaxis is described in prokaryotic and eukaryotic cells, but signalling mechanisms (receptors, intracellular signaling) and effectors are significantly different. Durotaxis is the directional movement of a cell along a stiffness gradient. Electrotaxis (or galvanotaxis) is the directional movement of motile cells along the vector of an electric field.
|
When does the diploid zygote form?
|
[
"after the pollen tube",
"never",
"before the pollen tube",
"before the haploid zygote"
] |
A
|
Chapter 26 1 Figure 26.8 B. The diploid zygote forms after the pollen tube has finished forming, so that the male generative nuclei can fuse with the female gametophyte. 3 D 5 C 7 A 9 B 11 C 13 B 15 C 17 D 19 Both pollination and herbivory contributed to diversity, with plants needing to attract some insects and repel others. 21 The trees are adapted to arid weather, and do not lose as much water due to transpiration as non-conifers. 23 The resemblance between cycads and palm trees is only superficial. Cycads are gymnosperms and do not bear flowers or fruit. Cycads produce cones: large, female cones that produce naked seeds, and smaller male cones on separate plants. Palms do not. 25 Using animal pollinators promotes cross-pollination and increases genetic diversity. The odds that the pollen will reach another flower are greatly increased compared with the randomness of wind pollination.
The diplobiontic forms, which evolved from haplobiontic ancestors, have both a multicellular haploid generation and a multicellular diploid generation. Here the zygote divides repeatedly by mitosis and grows into a multicellular diploid sporophyte. The sporophyte produces haploid spores by meiosis that germinate to produce a multicellular gametophyte.
Released from the binucleate sperm cell are two sperm nuclei which then join with free egg nuclei to produce two viable zygotes, a homologous characteristic between families Ephedra and Gnetum. In both families, the second fertilization event produces an additional diploid embryo. This supernumerary embryo is later aborted, leading to the synthesis of only one mature embryo.
Diplospory, a type of Agamospermy, occurs during the development of female gametophyte in the ovule and hence reduction division does not take place in the Megaspore mother cell. The diploid egg is unfertilized and forms the embryo. Hence daughter plants are exactly clones of the mother. The species uses C4 carbon fixation. It is dioecious, meaning male and female flowers are produced on separate individuals.
The resulting zygote germinates into a resting spore.Sexual reproduction is common and well known among members of the Monoblepharidomycetes. Typically, these chytrids practice a version of oogamy: The male is motile and the female is stationary. This is the first occurrence of oogamy in kingdom Fungi.
Eukaryotes have a life cycle that involves sexual reproduction, alternating between a haploid phase, where only one copy of each chromosome is present in each cell, and a diploid phase, with two copies of each chromosome in each cell. The diploid phase is formed by fusion of two haploid gametes, such as eggs and spermatozoa, to form a zygote; this may grow into a body, with its cells dividing by mitosis, and at some stage produce haploid gametes through meiosis, a division that reduces the number of chromosomes and creates genetic variability. There is considerable variation in this pattern.
|
What is the minimum number of times a partial lunar eclipse will occur each year?
|
[
"six",
"11",
"two",
"five"
] |
C
|
Partial lunar eclipses occur at least twice a year, but total lunar eclipses are less common. The Moon glows with a dull red coloring during a total lunar eclipse ( Figure below ).
Sometimes the new moon occurs close enough to a node during two consecutive months to eclipse the Sun on both occasions in two partial eclipses. This means that, in any given year, there will always be at least two solar eclipses, and there can be as many as five.Eclipses can occur only when the Sun is within about 15 to 18 degrees of a node, (10 to 12 degrees for central eclipses). This is referred to as an eclipse limit, and is given in ranges because the apparent sizes and speeds of the Sun and Moon vary throughout the year. In the time it takes for the Moon to return to a node (draconic month), the apparent position of the Sun has moved about 29 degrees, relative to the nodes. Since the eclipse limit creates a window of opportunity of up to 36 degrees (24 degrees for central eclipses), it is possible for partial eclipses (or rarely a partial and a central eclipse) to occur in consecutive months.
A partial solar eclipse on July 20. A partial solar eclipse on December 15. A total lunar eclipse on December 30.There are seven eclipses in 1982, the maximum possible, including 4 partial solar eclipses: January 25, July 20, June 21, and December 15.
Lunar saros series 129, repeating every 18 years and 11 days, containing 71 events, has 11 total lunar eclipses. The first total lunar eclipse of this series was on May 24, 1910, and last will be on September 8, 2090. The longest occurrence of this series was on July 16, 2000 when totality lasted 106 minutes and 24.6 seconds. It last occurred on June 14, 1946 and will next occur on July 6, 1982.
This eclipse is one of five lunar eclipses in a short-lived series. The lunar year series repeats after 12 lunations or 354 days (Shifting back about 10 days in sequential years). Because of the date shift, the Earth's shadow will be about 11 degrees west in sequential events.
A total lunar eclipse took place on Sunday, November 9, 2003, the second of two total lunar eclipses in 2003, the first being on May 16, 2003. It is the first total lunar eclipse of 21st century which happened on a micromoon day. The Moon barely edged into total eclipse for 21 minutes and 58 seconds.
|
Microscopes were first developed in the early 1600s by this trade?
|
[
"food makers",
"polyurethane makers",
"eyeglass makers",
"watch makers"
] |
C
|
Microscopes were first developed in the early 1600s by eyeglass makers in The Netherlands and Denmark. The simplest compound microscope is constructed from two convex lenses as shown schematically in Figure 26.16. The first lens is called the objective lens, and has typical magnification values from 5× to 100× . In standard microscopes, the objectives are mounted such that when you switch between objectives, the sample remains in focus. Objectives arranged in this way are described as parfocal. The second, the eyepiece, also referred to as the ocular, has several lenses which slide inside a cylindrical barrel. The focusing ability is provided by the movement of both the objective lens and the eyepiece. The purpose of a microscope is to magnify small objects, and both lenses contribute to the final magnification. Additionally, the final enlarged image is produced in a location far enough from the observer to be easily viewed, since the eye cannot focus on objects or images that are too close.
The discovery of the cell was made possible through the invention of the microscope. In the first century BC, Romans were able to make glass. They discovered that objects appeared to be larger under the glass. The expanded use of lenses in eyeglasses in the 13th century probably led to wider spread use of simple microscopes (magnifying glasses) with limited magnification.
An early digital microscope was made by a company in Tokyo, Japan in 1986, which is now known as Hirox Co. LTD. It included a control box and a lens connected to a computer. The original connection to the computer was analog through an S-video connection.
In 1610, he used a telescope at close range to magnify the parts of insects. By 1624, Galileo had used a compound microscope.
By the publication of the 7th, 1861, price list in August 1861, newly developed compound microscopes appear in 5 different versions. The largest of these, costing 55 Taler, was a horseshoe foot stand as made popular by the well known Parisian microscope maker Georg Oberhaeuser.
The first telescopes appeared in the Netherlands in 1608 when Middelburg spectacle-maker Hans Lippershey tried to obtain a patent on one. By 1609 Galileo had heard about it and built his own improved version. He probably was not the first person to aim the new invention at the night sky but his was the first systematic (and published) study of celestial bodies using one. One of Galileo's first telescopes had 8x to 10x linear magnification and was made out of lenses that he had ground himself. This was increased to 20x linear magnification in the improved telescope he used to make the observations in Sidereus Nuncius.
|
What do we call the temperature at which a substance melts?
|
[
"boiling point",
"precipitation point",
"evaporation point",
"melting point"
] |
D
|
The temperature at which a substance melts is called its melting point. The melting point of ice is 0°C.
The temperature at which a substance changes state from a solid to a liquid. It depends on pressure and is usually specified for a given substance under standard conditions. The melting point of a substance is identical to its freezing point.
For a solid to melt, heat is required to raise its temperature to the melting point. However, further heat needs to be supplied for the melting to take place: this is called the heat of fusion, and is an example of latent heat.From a thermodynamics point of view, at the melting point the change in Gibbs free energy (ΔG) of the material is zero, but the enthalpy (H) and the entropy (S) of the material are increasing (ΔH, ΔS > 0). Melting phenomenon happens when the Gibbs free energy of the liquid becomes lower than the solid for that material. At various pressures this happens at a specific temperature.
In chemistry, materials science, and physics, the solidus is the locus of temperatures (a curve on a phase diagram) below which a given substance is completely solid (crystallized). The solidus temperature, TS or Tsol, specifies the temperature below which a material is completely solid, and the minimum temperature at which a melt can co-exist with crystals in thermodynamic equilibrium. The solidus is applied, among other materials, to metal alloys, ceramics, and natural rocks and minerals. The solidus quantifies the temperature at which melting of a substance begins, but the substance is not necessarily melted completely, i.e., the solidus is not necessarily a melting point.
For example, the melting point of silicon at ambient pressure (0.1 MPa) is 1415 °C, but at pressures in excess of 10 GPa it decreases to 1000 °C.Melting points are often used to characterize organic and inorganic compounds and to ascertain their purity. The melting point of a pure substance is always higher and has a smaller range than the melting point of an impure substance or, more generally, of mixtures. The higher the quantity of other components, the lower the melting point and the broader will be the melting point range, often referred to as the "pasty range".
As heat is added to this substance it melts into a liquid at its melting point, boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized that they leave their parent atoms. Forms of matter that are not composed of molecules and are organized by different forces can also be considered different states of matter.
|
What is the small, dense region at the center of the atom that consists of positive protons and neutral neutrons?
|
[
"proton",
"nucleus",
"electron",
"photon"
] |
B
|
The nucleus is a small, dense region at the center of the atom. It consists of positive protons and neutral neutrons, so it has an overall positive charge.
Atoms are the smallest neutral particles into which matter can be divided by chemical reactions. An atom consists of a small, heavy nucleus surrounded by a relatively large, light cloud of electrons. An atomic nucleus typically consists of 1 or more protons and 0 or more neutrons. Protons and neutrons are, in turn, made of quarks.
Atomic nuclei consist of protons and neutrons bound together by the residual strong force. Because protons are positively charged, they repel each other. Neutrons, which are electrically neutral, stabilize the nucleus in two ways. Their copresence pushes protons slightly apart, reducing the electrostatic repulsion between the protons, and they exert the attractive nuclear force on each other and on protons.
This was the first determination of the pole position for a hyperon. The lambda baryon has also been observed in atomic nuclei called hypernuclei. These nuclei contain the same number of protons and neutrons as a known nucleus, but also contains one or in rare cases two lambda particles. In such a scenario, the lambda slides into the center of the nucleus (it is not a proton or a neutron, and thus is not affected by the Pauli exclusion principle), and it binds the nucleus more tightly together due to its interaction via the strong force. In a lithium isotope (7ΛLi), it made the nucleus 19% smaller.
Understanding the structure of the atomic nucleus is one of the central challenges in nuclear physics.
This gives a critical density of 0.85×10−26 kg/m3, or about 5 hydrogen atoms per cubic metre. This density includes four significant types of energy/mass: ordinary matter (4.8%), neutrinos (0.1%), cold dark matter (26.8%), and dark energy (68.3%). Although neutrinos are Standard Model particles, they are listed separately because they are ultra-relativistic and hence behave like radiation rather than like matter.
|
By multiplying the force applied by the perpendicular component of the moment arm,what is determined?
|
[
"radiation",
"intensities",
"pressure",
"torques"
] |
D
|
Individual torques are determined by multiplying the force applied by the perpendicular component of the moment arm.
A muscle's moment arm is defined as the perpendicular distance from the muscle's line of action to the joint's center of rotation. As a general rule, the larger the moment arm of a muscle, the greater torque it can produce with the same amount of force. At the same time, the muscle would cause a smaller change in joint angle for the same amount of length change. As an example, holding a wrench at the very end of the handle (point B) makes it easier to loosen a bolt, however, requires your hand to travel a greater distance compared to holding the wrench closer to the bolt (point A).
The symbol for torque is typically τ {\displaystyle {\boldsymbol {\tau }}} , the lowercase Greek letter tau. When being referred to as moment of force, it is commonly denoted by M. In three dimensions, the torque is a pseudovector; for point particles, it is given by the cross product of the displacement vector and the force vector. The magnitude of torque applied to a rigid body depends on three quantities: the force applied, the lever arm vector connecting the point about which the torque is being measured to the point of force application, and the angle between the force and lever arm vectors. In symbols: τ = r × F {\displaystyle {\boldsymbol {\tau }}=\mathbf {r} \times \mathbf {F} } τ = r F sin θ , {\displaystyle \tau =rF\sin \theta ,} where τ {\displaystyle {\boldsymbol {\tau }}} is the torque vector and τ {\displaystyle \tau } is the magnitude of the torque, r {\displaystyle \mathbf {r} } is the position vector (a vector from the point about which the torque is being measured to the point where the force is applied), and r is the magnitude of the position vector, F {\displaystyle \mathbf {F} } is the force vector, and F is the magnitude of the force vector, × {\displaystyle \times } denotes the cross product, which produces a vector that is perpendicular both to r and to F following the right-hand rule, θ {\displaystyle \theta } is the angle between the force vector and the lever arm vector.The SI unit for torque is the newton-metre (N⋅m). For more on the units of torque, see § Units.
The moment of inertia, otherwise known as the mass moment of inertia, angular mass, second moment of mass, or most accurately, rotational inertia, of a rigid body is a quantity that determines the torque needed for a desired angular acceleration about a rotational axis, akin to how mass determines the force needed for a desired acceleration. It depends on the body's mass distribution and the axis chosen, with larger moments requiring more torque to change the body's rate of rotation. It is an extensive (additive) property: for a point mass the moment of inertia is simply the mass times the square of the perpendicular distance to the axis of rotation. The moment of inertia of a rigid composite system is the sum of the moments of inertia of its component subsystems (all taken about the same axis).
An experimental method to locate the three-dimensional coordinates of the center of mass begins by supporting the object at three points and measuring the forces, F1, F2, and F3 that resist the weight of the object, W = − W k ^ {\displaystyle \mathbf {W} =-W\mathbf {\hat {k}} } ( k ^ {\displaystyle \mathbf {\hat {k}} } is the unit vector in the vertical direction). Let r1, r2, and r3 be the position coordinates of the support points, then the coordinates R of the center of mass satisfy the condition that the resultant torque is zero, or This equation yields the coordinates of the center of mass R* in the horizontal plane as, The center of mass lies on the vertical line L, given by The three-dimensional coordinates of the center of mass are determined by performing this experiment twice with the object positioned so that these forces are measured for two different horizontal planes through the object. The center of mass will be the intersection of the two lines L1 and L2 obtained from the two experiments.
{\displaystyle {\vec {AP}}=m_{B}\cdot {\vec {AB}}+m_{C}\cdot {\vec {AC}},\,{\mbox{ where }}\,m_{B}={\frac {({\vec {AP}},{\vec {AC}},\mathbf {k} )}{({\vec {AB}},{\vec {AC}},\mathbf {k} )}},\,m_{C}={\frac {({\vec {AB}},{\vec {AP}},\mathbf {k} )}{({\vec {AB}},{\vec {AC}},\mathbf {k} )}}.} Given the positive (counterclockwise) orientation of triangle A B C {\displaystyle ABC} , the denominator of both m B {\displaystyle m_{B}} and m C {\displaystyle m_{C}} is precisely the double of the area of the triangle A B C {\displaystyle ABC} . Also, ( A P → , A C → , k ) = ( P C → , P A → , k ) and ( A B → , A P → , k ) = ( P A → , P B → , k ) {\displaystyle ({\vec {AP}},{\vec {AC}},\mathbf {k} )=({\vec {PC}},{\vec {PA}},\mathbf {k} )\,{\mbox{ and }}\,({\vec {AB}},{\vec {AP}},\mathbf {k} )=({\vec {PA}},{\vec {PB}},\mathbf {k} )} and so the numerators of m B {\displaystyle m_{B}} and m C {\displaystyle m_{C}} are the doubles of the signed areas of triangles A P C {\displaystyle APC} and respectively A B P {\displaystyle ABP} .
|
What carry messages from our sensory organs and others to the central nervous system?
|
[
"fibers",
"valves",
"nerves",
"blood vessels"
] |
C
|
20.7 Nerve Conduction–Electrocardiograms Nerve Conduction Electric currents in the vastly complex system of billions of nerves in our body allow us to sense the world, control parts of our body, and think. These are representative of the three major functions of nerves. First, nerves carry messages from our sensory organs and others to the central nervous system, consisting of the brain and spinal cord. Second, nerves carry messages from the central nervous system to muscles and other organs. Third, nerves transmit and process signals within the central nervous system. The sheer number of nerve cells and the incredibly greater number of connections between them makes this system the subtle wonder that it is. Nerve conduction is a general term for electrical signals carried by nerve cells. It is one aspect of bioelectricity, or electrical effects in and created by biological systems. Nerve cells, properly called neurons, look different from other cells—they have tendrils, some of them many centimeters long, connecting them with other cells. (See Figure 20.27. ) Signals arrive at the cell body across synapses or through dendrites, stimulating the neuron to generate its own signal, sent along its long axon to other nerve or muscle cells. Signals may arrive from many other locations and be transmitted to yet others, conditioning the synapses by use, giving the system its complexity and its ability to learn.
During sensation, sense organs collect various stimuli (such as a sound or smell) for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought. In organisms, a sensory organ consists of a group of interrelated sensory cells that respond to a specific type of physical stimulus.
The autonomic nervous system itself consists of two parts: the sympathetic nervous system and the parasympathetic nervous system. Some authors also include sensory neurons whose cell bodies lie in the periphery (for senses such as hearing) as part of the PNS; others, however, omit them.The vertebrate nervous system can also be divided into areas called gray matter and white matter.
The pathway fibres travel up the back part of the spinal cord to the back part of the medulla, where they connect with second-order neurons that immediately send fibres across the midline. These fibres then travel upwards into the ventrobasal complex in the thalamus where they connect with third-order neurons which send fibres up to the sensory cortex. The spinothalamic tract carries information about pain, temperature, and gross touch.
All sensory and motor pathways converge and diverge to the contralateral hemisphere.Although sensory pathways are often depicted as chains of individual neurons connected in series, this is an oversimplification. Sensory information is processed and modified at each level in the chain by interneurons and input from other areas of the nervous system. For example, cells in the main trigeminal nucleus (Main V in the diagram below) receive input from the reticular formation and cerebellar cortex.
All afferent touch/vibration info ascends the spinal cord via the dorsal column-medial lemniscus pathway via gracilis (T7 and below) or cuneatus (T6 and above). Cuneatus sends signals to the cochlear nucleus indirectly via spinal grey matter, this info is used in determining if a perceived sound is just villi noise/irritation. All fibers cross (left becomes right) in the medulla. A somatosensory pathway will typically have three neurons: first-order, second-order, and third-order.
|
What do you call the space around a charged particle where the particle exerts electric force on other charged particles?
|
[
"electric field",
"melodic field",
"powered field",
"charged field"
] |
A
|
An electric field is a space around a charged particle where the particle exerts electric force on other charged particles. Because of their force fields, charged particles can exert force on each other without actually touching. Electric fields are generally represented by arrows, as you can see in the Figure below . The arrows show the direction of electric force around a positive particle and a negative particle. For an animated diagram, go to this URL: http://ocw. mit. edu/ans7870/8/8.02T/f04/visualizations/electrostatics/15-CreateField/CreateField_640. mpg.
Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber, ἤλεκτρον (ḗlektron), was thus the source of the word 'electricity'. Electrostatic phenomena arise from the forces that electric charges exert on each other.
The charge of an antiparticle equals that of the corresponding particle, but with opposite sign. The electric charge of a macroscopic object is the sum of the electric charges of the particles that it's made up of. This charge is often small, because matter is made of atoms, and atoms typically have equal numbers of protons and electrons, in which case their charges cancel out, yielding a net charge of zero, thus making the atom neutral.
For example, the electric charge of a particle is a coupling constant that characterizes an interaction with two charge-carrying fields and one photon field (hence the common Feynman diagram with two arrows and one wavy line). Since photons mediate the electromagnetic force, this coupling determines how strongly electrons feel such a force, and has its value fixed by experiment.
The concept of the electric field was introduced by Michael Faraday. An electric field is created by a charged body in the space that surrounds it, and results in a force exerted on any other charges placed within the field. The electric field acts between two charges in a similar manner to the way that the gravitational field acts between two masses, and like it, extends towards infinity and shows an inverse square relationship with distance. However, there is an important difference.
Electric current is a flow of electrically charged particles in a material caused by an electric field. The mobile charged particles responsible for electric current are called charge carriers. In different substances different particles serve as charge carriers: in metals and other solids some of the outer electrons of each atom (conduction electrons) are able to move about the material; in electrolytes and plasma it is ions, electrically charged atoms or molecules, and electrons. A substance that has a high concentration of charge carriers available for conduction will conduct a large current with the given electric field created by a given voltage applied across it, and thus has a low electrical resistivity; this is called an electrical conductor.
|
Natural convection is driven by what forces?
|
[
"buoyant",
"magnetic",
"thermal",
"gravitational"
] |
A
|
sweating. These vessels become smaller when it is cold outside and larger when it is hot (so more fluid flows, and more energy is transferred). The body also loses a significant fraction of its heat through the breathing process. While convection is usually more complicated than conduction, we can describe convection and do some straightforward, realistic calculations of its effects. Natural convection is driven by buoyant forces: hot air rises because density decreases as temperature increases. The house in Figure 14.17 is kept warm in this manner, as is the pot of water on the stove in Figure 14.18. Ocean currents and large-scale atmospheric circulation transfer energy from one part of the globe to another. Both are examples of natural convection.
Natural convection also plays a role in stellar physics. Convection is often categorised or described by the main effect causing the convective flow, e.g. Thermal convection.
Such movement is called convection, and the moving body of liquid is referred to as a convection cell. This particular type of convection, where a horizontal layer of fluid is heated from below, is known as Rayleigh–Bénard convection. Convection usually requires a gravitational field, but in microgravity experiments, thermal convection has been observed without gravitational effects.Fluids are generalized as materials that exhibit the property of flow; however, this behavior is not unique to liquids.
Two types of convective heat transfer may be distinguished: Free or natural convection: when fluid motion is caused by buoyancy forces that result from the density variations due to variations of thermal ±temperature in the fluid. In the absence of an internal source, when the fluid is in contact with a hot surface, its molecules separate and scatter, causing the fluid to be less dense. As a consequence, the fluid is displaced while the cooler fluid gets denser and the fluid sinks. Thus, the hotter volume transfers heat towards the cooler volume of that fluid.
Donald W. Burgess, Steering Committee, Scientific PI, Scientist at CIMMS. David Dowell, Steering Committee, Scientific PI, Scientist, National Center for Atmospheric Research. Jeffrey Frame, Professor University of Illinois at Urbana-Champaign, expert in severe convection.
Convection in a large magma chamber is subject to the interplay of forces generated by thermal convection and the resistance offered by friction, viscosity and drag on the magma offered by the walls of the magma chamber. Often near the margins of a magma chamber which is convecting, cooler and more viscous layers form concentrically from the outside in, defined by breaks in viscosity and temperature. This forms laminar flow, which separates several domains of the magma chamber which can begin to differentiate separately.
|
Materials that can be magnetized are called?
|
[
"atoms materials",
"iron materials",
"inclusions materials",
"ferromagnetic materials"
] |
D
|
In other materials, electrons fill the orbitals of the atoms that make up the material in a way to allow for each atom to have a tiny magnetic field, giving each atom a tiny north and south pole. There are large areas where the north and south poles of atoms are all lined up in the same direction. These areas are called magnetic domains . Generally, the magnetic domains point in different directions, so the material is still not magnetic. However, the material can be magnetized by placing it in a magnetic field. When this happens, all the magnetic domains become aligned, and the material becomes a magnet. This is illustrated in Figure below . Materials that can be magnetized are called ferromagnetic materials . They include iron, cobalt, and nickel.
Magnetocrystalline anisotropy has a great influence on industrial uses of ferromagnetic materials. Materials with high magnetic anisotropy usually have high coercivity, that is, they are hard to demagnetize. These are called "hard" ferromagnetic materials and are used to make permanent magnets. For example, the high anisotropy of rare-earth metals is mainly responsible for the strength of rare-earth magnets.
This is a single-phase material. Multiferroics are another example of single-phase materials that can exhibit a general magnetoelectric effect if their magnetic and electric orders are coupled. Composite materials are another way to realize magnetoelectrics.
These include iron ore (magnetite or lodestone), cobalt and nickel, as well as the rare earth metals gadolinium and dysprosium (when at a very low temperature). Such naturally occurring ferromagnets were used in the first experiments with magnetism. Technology has since expanded the availability of magnetic materials to include various man-made products, all based, however, on naturally magnetic elements.
The material is said to be "unmagnetized". However, the domains can also exist in other configurations in which their magnetization mostly points in the same direction, creating an external magnetic field. Although these are not minimum energy configurations, due to a phenomenon where the domain walls become "pinned" to defects in the crystal lattice they can be local minimums of the energy, and therefore can be very stable.
The material would not be intrinsically magnetic, nor inherently susceptible to being magnetized. Copper wire is such a non-magnetic material. He envisioned fabricating a non-magnetic composite material, which could mimic the movements of electrons orbiting atoms.
|
The overall purpose of the light-dependent reactions is to convert light energy into this?
|
[
"chemical reactions",
"photosynthesis",
"thermal energy",
"calories"
] |
A
|
How Light-Dependent Reactions Work The overall purpose of the light-dependent reactions is to convert light energy into chemical energy. This chemical energy will be used by the Calvin cycle to fuel the assembly of sugar molecules. The light-dependent reactions begin in a grouping of pigment molecules and proteins called a photosystem. Photosystems exist in the membranes of thylakoids. A pigment molecule in the photosystem absorbs one photon, a quantity or “packet” of light energy, at a time. A photon of light energy travels until it reaches a molecule of chlorophyll. The photon causes an electron in the chlorophyll to become “excited. ” The energy given to the electron allows it to break free from an atom of the chlorophyll molecule. Chlorophyll is therefore said to “donate” an electron (Figure 5.12). To replace the electron in the chlorophyll, a molecule of water is split. This splitting releases an electron and results in the formation of oxygen (O2) and hydrogen ions (H+) in the thylakoid space. Technically, each breaking of a water molecule releases a pair of electrons, and therefore can replace two donated electrons.
The net-reaction of all light-dependent reactions in oxygenic photosynthesis is: 2H2O + 2NADP+ + 3ADP + 3Pi → O2 + 2 H+ + 2NADPH + 3ATPPSI and PSII are light-harvesting complexes. If a special pigment molecule in a photosynthetic reaction center absorbs a photon, an electron in this pigment attains the excited state and then is transferred to another molecule in the reaction center. This reaction, called photoinduced charge separation, is the start of the electron flow and transforms light energy into chemical forms.
In plants, light-dependent reactions occur in the thylakoid membranes of the chloroplasts where they drive the synthesis of ATP and NADPH. The light-dependent reactions are of two forms: cyclic and non-cyclic. In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments (see diagram at right). The absorption of a photon by the antenna complex loosens an electron by a process called photoinduced charge separation.
This area of Photobiology focuses on the physical interactions of light and matter. When molecules absorb photons that matches their energy requirements they promote a valence electron from a ground state to an excited state and they become a lot more reactive. This is an extremely fast process, but very important for different processes.
In energy terms, natural photosynthesis can be divided in three steps: Light-harvesting complexes in bacteria and plants capture photons and transduce them into electrons, injecting them into the photosynthetic chain. Proton-coupled electron transfer along several cofactors of the photosynthetic chain, causing local, spatial charge separation. Redox catalysis, which uses the aforementioned transferred electrons to oxidize water to dioxygen and protons; these protons can in some species be utilized for dihydrogen production.Using biomimetic approaches, artificial photosynthesis tries to construct systems doing the same type of processes. Ideally, a triad assembly could oxidize water with one catalyst, reduce protons with another and have a photosensitizer molecule to power the whole system.
Light radiation provides energy to induce chemical changes within the molecular structure of materials. Damage from light, including loss of color and strength, is cumulative and irreversible.Controlling light damage is a process of compromise, as light is also necessary for people working with or viewing cultural heritage objects. Light exposure can be reduced by limiting either the amount of time sensitive objects are put on display, or the strength at which they are illuminated.
|
Jellyfish belong to which phylum?
|
[
"porifera",
"analidae",
"cnidaria",
"mycobacteria"
] |
C
|
Do you know what these greenish, blob-like shapes are? Would it surprise you to learn that they are animals? They don’t look anything like the animals you are probably familiar with—animals such as dogs and deer, fish and frogs. But the greenish blobs are animals nonetheless. They belong to a phylum called Cnidaria, but you may know them as jellyfish. They are very simple animals and not fish at all.
Jellyfish have a complex life cycle; the medusa is normally the sexual phase, which produces planula larvae that disperse widely and enter a sedentary polyp phase before reaching sexual maturity. Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater.
This unicellular organism settles in the tissue of jellyfishes. It provides products of photosynthesis to the jellyfish, and in return, the jellyfish provides it minerals and nutrients from the soil and the sea water.In addition to this symbiosis, the spotted jelly has several small mouths used to grab animal plankton. These mouths are disposed all along its oral arms.
The helmet jellyfish (Periphylla periphylla), sometimes called the merchant-cap, is a luminescent, red-colored jellyfish of the deep sea, belonging to the order Coronatae of the phylum Cnidaria. It is the only species in the monotypic genus Periphylla and is one of the rare examples in Scyphozoa which life-cycle lacks a polyp stage. This species is photophobic and inhabits deeper parts of the oceans to avoid light. It may be found at the surface on dark nights.
Jellyfish are well placed to benefit from disturbance of marine ecosystems. They reproduce rapidly; they prey upon many species, while few species prey on them; and they feed via touch rather than visually, so they can feed effectively at night and in turbid waters. It may be difficult for fish stocks to re-establish themselves in marine ecosystems once they have become dominated by jellyfish, because jellyfish feed on plankton, which includes fish eggs and larvae.
A phylum is the highest level in the Linnaean system for classifying organisms. Phyla can be thought of as groupings of animals based on general body plan. Despite the seemingly different external appearances of organisms, they are classified into phyla based on their internal and developmental organizations. For example, despite their obvious differences, spiders and barnacles both belong to the phylum Arthropoda, but earthworms and tapeworms, although similar in shape, belong to different phyla.
|
Along with changes in the shape of the resonant cavity, growth of what organ in pubescent boys leads to the difference in predominant frequencies in speech between men and women?
|
[
"pharynx",
"larynx",
"trachea",
"esoophagus"
] |
B
|
The fundamental and overtones can be present simultaneously in a variety of combinations. For example, middle C on a trumpet has a sound distinctively different from middle C on a clarinet, both instruments being modified versions of a tube closed at one end. The fundamental frequency is the same (and usually the most intense), but the overtones and their mix of intensities are different and subject to shading by the musician. This mix is what gives various musical instruments (and human voices) their distinctive characteristics, whether they have air columns, strings, sounding boxes, or drumheads. In fact, much of our speech is determined by shaping the cavity formed by the throat and mouth and positioning the tongue to adjust the fundamental and combination of overtones. Simple resonant cavities can be made to resonate with the sound of the vowels, for example. (See Figure 17.30. ) In boys, at puberty, the larynx grows and the shape of the resonant cavity changes giving rise to the difference in predominant frequencies in speech between men and women.
This growth is far more prominent in males than in females and is more easily perceived. It causes the voice to drop and deepen. Along with the larynx, the vocal folds (vocal cords) grow significantly longer and thicker.
Studies of the frequency spectrum of trained speakers and classical singers, especially male singers, indicate a clear formant around 3000 Hz (between 2800 and 3400 Hz) that is absent in speech or in the spectra of untrained speakers or singers. It is thought to be associated with one or more of the higher resonances of the vocal tract. It is this increase in energy at 3000 Hz which allows singers to be heard and understood over an orchestra. This formant is actively developed through vocal training, for instance through so-called voce di strega or "witch's voice" exercises and is caused by a part of the vocal tract acting as a resonator. In classical music and vocal pedagogy, this phenomenon is also known as squillo.
When a person speaks after inhaling helium gas, the muscles that control the voice box still move in the same way as when the voice box is filled with air, therefore the fundamental frequency (sometimes called pitch) produced by direct vibration of the vocal folds does not change. However, the high-frequency-preferred amplification causes a change in timbre of the amplified sound, resulting in a reedy, duck-like vocal quality. The opposite effect, lowering resonant frequencies, can be obtained by inhaling a dense gas such as sulfur hexafluoride or xenon.
These changes are predictable. The vocal tract can be modeled as a sequence of tubes, closed at one end, with varying diameters, and by using equations for acoustic resonance the acoustic effect of an articulatory posture can be derived. The process of inverse filtering uses this principle to analyze the source spectrum produced by the vocal folds during voicing. By taking the inverse of a predicted filter, the acoustic effect of the supraglottal vocal tract can be undone giving the acoustic spectrum produced by the vocal folds. This allows quantitative study of the various phonation types.
Features of the voiced palato-alveolar fricative: Its manner of articulation is sibilant fricative, which means it is generally produced by channeling air flow along a groove in the back of the tongue up to the place of articulation, at which point it is focused against the sharp edge of the nearly clenched teeth, causing high-frequency turbulence. Its place of articulation is palato-alveolar, that is, domed (partially palatalized) postalveolar, which means it is articulated with the blade of the tongue behind the alveolar ridge, and the front of the tongue bunched up ("domed") at the palate. Its phonation is voiced, which means the vocal cords vibrate during the articulation.
|
What intensifies the response during homeostasis?
|
[
"positive feedback loops",
"pressure loops",
"pure loops",
"negative feedback loops"
] |
A
|
1.5 Homeostasis Homeostasis is the activity of cells throughout the body to maintain the physiological state within a narrow range that is compatible with life. Homeostasis is regulated by negative feedback loops and, much less frequently, by positive feedback loops. Both have the same components of a stimulus, sensor, control center, and effector; however, negative feedback loops work to prevent an excessive response to the stimulus, whereas positive feedback loops intensify the response until an end point is reached.
Organisms, when presented with the problem of regulating body temperature, have not only behavioural, physiological, and structural adaptations but also a feedback system to trigger these adaptations to regulate temperature accordingly. The main features of this system are stimulus, receptor, modulator, effector and then the feedback of the newly adjusted temperature to the stimulus. This cyclical process aids in homeostasis.
The ANS receives inputs from the medulla, hypothalamus, limbic system, prefrontal cortex, midbrain and monoamine nuclei.The activity of the sympathetic nervous system drives what is called the "fight or flight" response. The fight or flight response to emergency or stress involves mydriasis, increased heart rate and force contraction, vasoconstriction, bronchodilation, glycogenolysis, gluconeogenesis, lipolysis, sweating, decreased motility of the digestive system, secretion of the epinephrine and cortisol from the adrenal medulla, and relaxation of the bladder wall. The parasympathetic nervous response, "rest and digest", involves return to maintaining homeostasis, and involves miosis, bronchoconstriction, increased activity of the digestive system, and contraction of the bladder walls.
The general adaptation syndrome (GAS) is a three-phase response to stress in animals. The first phase is the fight or flight response – the animal flight zone is included in this. Over penetration of the animal flight zone causes stimulation of the sympathetic nervous system (SNS). The SNS produces localised adjustments and responses; this includes the excretion of large quantities of epinephrine from the medulla of the adrenal gland.
The spinal cord and spinal nerves contribute to homeostasis by providing quick reflexive responses to many stimuli. The spinal cord is the pathway for sensory input to the brain and motor output from the brain. The brain is responsible for integrating most sensory information and coordinating body function, both consciously and unconsciously.
Homeostatic outbalances are the main driving force for changes of the body. These stimuli are monitored closely by receptors and sensors in different parts of the body. These sensors are mechanoreceptors, chemoreceptors and thermoreceptors that, respectively, respond to pressure or stretching, chemical changes, or temperature changes. Examples of mechanoreceptors include baroreceptors which detect changes in blood pressure, Merkel's discs which can detect sustained touch and pressure, and hair cells which detect sound stimuli.
|
What is captured by the sticky structure at the top of the style called the stigma?
|
[
"pollen",
"fungi",
"sunlight",
"precipitation"
] |
A
|
The outline is drawn out in small dots with an etching needle, and the darker areas of the image shaded with a pattern of close dots. As in mezzotint use was made of roulettes, and a mattoir to produce large numbers of dots relatively quickly. Then the plate is bitten with acid, and the etching ground removed.
The meeting of the shaft with the foot is taken up by a wide vertically ribbed band. The foot is decorated with similar motifs to the cone itself. Near the reinforcing bronze band, it turns into a brim, also decorated with disk-shaped symbols.
4. The knob at the end of the stigmal or radial veins in the wings of certain Hymenoptera.
The finished surface below the fascia and rafters is called the soffit or eave. In classical architecture, the fascia is the plain, wide band (or bands) that make up the architrave section of the entablature, directly above the columns. The guttae or drip edge was mounted on the fascia in the Doric order, below the triglyph. The term fascia can also refer to the flat strip below the cymatium.
The Bull Palette (remainder piece about 10 inches (25 cm)) is made of mudstone or schist, and is etched in more atypical medium to medium-low relief than similar cosmetic palettes. A presumed 'fortified city' on the obverse (front) in the upper register has a major loss of the city-rectangle on upper left showing this medium-level bas relief. The register below appears to be a smaller area of the palette, and has the remains, (approximately one quarter), of a second fortified city; a bird is one identifier in the second city-fortified interior, with the rest missing.
|
What is the term for a sac filled with fluid or other material?
|
[
"blister",
"lesion",
"cyst",
"tumor"
] |
C
|
A common disorder of the ovaries is an ovarian cyst . A cyst is a sac filled with fluid or other material. An ovarian cyst is usually harmless, but it may cause pain. Most cysts slowly disappear and do not need treatment. Very large or painful cysts can be removed with surgery.
Clinically, this material was initially used as a biomaterial to replace the lost osseous tissues in the human body. These fillings are a mixture of glass and an organic acid. Although they are tooth-colored, glass ionomers vary in translucency.
These objects include bowls, flowerpots, jugs, mugs, plates, and tiles. In that sense, the use of materials gives voice to a Mcluhanesque view where "the medium is truly the message". By their existence, the materials used eloquently imply that the material is their substance, and that shape is peripheral.
Fillet 1. A small band, either raised or sunken and usually square, used to separate mouldings. 2.
The fluid is clear or pale yellow. If the amniotic sac has not yet broken during labour the health care provider may break it in a technique called an amniotomy. In an amniotomy a thin plastic hook is used to make a small opening in the sac, causing the water to break.
This is called a shear band. The pore network is rearranged by granular movements (also called particulate flow), hence moderately enhance permeability. However, continuing deformation leads to the cataclasis of mineral grains which will further reduce permeability later on (section 3.2.3) (Figure 4).
|
What organ protects the body from injury, water loss, and microorganisms?
|
[
"heart",
"hair",
"skin",
"liver"
] |
C
|
Skin protects the body from injury, water loss, and microorganisms. It also plays a major role in maintaining a stable body temperature. Common skin problems include acne and skin cancer.
The body responds to traumatic injury both systemically and at the injury site. This response attempts to protect vital organs such as the liver, to allow further cell duplication and to heal the damage. The healing time of an injury depends on various factors including sex, age, and the severity of injury.The symptoms of injury may manifest in many different ways, including: Altered mental status Fever Increased heart rate Generalized edema Increased cardiac output Increased rate of metabolismVarious organ systems respond to injury to restore homeostasis by maintaining perfusion to the heart and brain. Inflammation after injury occurs to protect against further damage and starts the healing process.
The organism enters directly through the breakdown of mechanical defense barriers such as mucosa or skin. Conditions which lead to the development of an immunocompromised state make the patient more susceptible to ecthyma gangrenosum and sepsis. In case of sepsis, the bacteria reaches the skin via the bloodstream.
For example, low pH (ranging from 1 to 4) of the stomach is fatal for many microorganisms that enter it. Similarly, mucus (containing IgA antibodies) neutralizes many pathogenic microorganisms. Other factors in the GI tract contribution to immune function include enzymes secreted in the saliva and bile.
Extracellular water freezes and tissue is destroyed. It affects fingers, toes, nose, ears and cheeks particularly often.
In systems already stressed by the natural disaster, the potential morbidity associated with skin infections or reactions can be life-threatening and is preventable with limited-exposure and post-exposure safety measures are taken. Centers for Disease Control and Prevention recommendations: Avoiding contact with flood waters if one has an open wound. Covering clean, open wounds with a waterproof bandage to reduce the chance of infection.
|
In which phase do the sister chromatids separate?
|
[
"prophase",
"anaphase",
"passivation",
"latent phase"
] |
B
|
Anaphase is the phase in which the sister chromatids separate. The sister chromatids are pulled apart by the shortening of the microtubules of the spindles, similar to the reeling in of a fish by the shortening of the fishing line. One sister chromatid moves to one pole of the cell, and the other sister chromatid moves to the opposite pole. This process occurs when the proteins that bind sister chromatids together are cleaved, resulting in unattached identical chromosomes, essentially separate daughter chromosomes. These separate chromosomes are pulled apart by shortening spindle fibers, and pulled toward the centrosomes to which they are attached. At the end of anaphase the spindle fibers degrade. At this time, each pole of the cell has a complete set of chromosomes, identical to the amount of DNA at the beginning of G 1 of the cell cycle.
Homologous chromosomes are separated in the first division (meiosis I), and sister chromatids are separated in the second division (meiosis II). Both of these cell division cycles are used in the process of sexual reproduction at some point in their life cycle. Both are believed to be present in the last eukaryotic common ancestor.
As shown by Uhlmann et al., during the attachment of chromosomes to the mitotic spindle the chromatids remain paired because cohesion between the sisters prevents separation. Cohesion is established during DNA replication and depends on cohesin, which is a multisubunit complex composed of Scc1, Scc3, Smc2, and Smc3.
Synthesis (S) phase: The genetic material is replicated; each of the cell's chromosomes duplicates to become two identical sister chromatids attached at a centromere. This replication does not change the ploidy of the cell since the centromere number remains the same.
The two sister chromatids are initially bound together by the cohesin complex until the beginning of anaphase, at which point the mitotic spindle pulls the two sister chromatids apart, leaving each of the two daughter cells with an equivalent number of sister chromatids. The proteins that bind the two sister chromatids, disallowing any premature sister chromatid separation, are a part of the cohesin protein family. One of these cohesin proteins crucial for sister chromatid cohesion is Scc1. Esp1 is a separase protein that cleaves the cohesin subunit Scc1 (RAD21), allowing sister chromatids to separate at the onset of anaphase during mitosis.
Cytokinesis, the pinching of the cell membrane in animal cells or the formation of the cell wall in plant cells, occurs, completing the creation of two daughter cells. However, cytokinesis does not fully complete resulting in "cytoplasmic bridges" which enable the cytoplasm to be shared between daughter cells until the end of meiosis II. Sister chromatids remain attached during telophase I. Cells may enter a period of rest known as interkinesis or interphase II. No DNA replication occurs during this stage.
|
Pinocytosis or "cellular drinking," occurs when the plasma membrane folds inward to form a channel allowing dissolved substances to enter what?
|
[
"proteins",
"cell",
"nucleus",
"homeostasis"
] |
B
|
Pinocytosis or "cellular drinking," occurs when the plasma membrane folds inward to form a channel allowing dissolved substances to enter the cell, as shown in Figure below . When the channel is closed, the liquid is encircled within a pinocytic vesicle.
Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested material. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating). It is a form of active transport.
In pinocytosis, cells engulf liquid particles (in humans this process occurs in the small intestine, where cells engulf fat droplets). In phagocytosis, cells engulf solid particles.Exocytosis involves the removal of substances through the fusion of the outer cell membrane and a vesicle membrane. An example of exocytosis would be the transmission of neurotransmitters across a synapse between brain cells.
Exocytosis is the process by which a large amount of molecules are released; thus it is a form of bulk transport. Exocytosis occurs via secretory portals at the cell plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structures at the cell plasma membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell.
The word pinocytosis () uses combining forms of pino- + cyto- + -osis, all Neo-Latin from Greek, reflecting píno, to drink, and cytosis. The term was proposed by W. H. Lewis in 1931.
This tendency is countered by manipulating the flow of sodium and potassium ions. A 'pump' forces sodium out of the cell and potassium in, and this action is balanced by a process called 'the passive leak'. In overhydrated hereditary stomatocytoses, the passive leak is increased and the erythrocyte becomes swamped with salt and water.
|
Adult tunicates also develop a sac, called a what?
|
[
"tunic",
"hood",
"skirt",
"frill"
] |
A
|
24.2 Subphylum Urochordata The tunicates are located in this subphylum. Along with the subphylum Cephalochordata, these two subphyla make up the invertebrate chordates. Only the tunicate larvae have notochords, nerve cords, and postanal tails. Most adult tunicates are sessile, filter-feeders which retain their pharyngeal slits. Adult tunicates also develop a sac, called a tunic, which gives tunicates their name. Cilia beating within the turnicate cause water to enter the incurrent siphon. The water enters the body, passes through the pharyngeal slits, and leaves the body through the excurrent siphon. Undigested food is removed through the anus. Tunicates are hemaphrodites and can reproduce asexually through budding. In urochordates notochord is confined to larval tail. These lack cranium. These have an open type of circulatory system. Excretion is by neural gland,nephrocytes.
In modern biology in general, tunica occurs as a technical or anatomical term mainly in botany and zoology. It usually refers to membranous structures that line or cover particular organs. In many such contexts tunica is used interchangeably with tunic according to preference. An organ or organism that has a tunic(a) may be said to be tunicate, as in a tunicate bulb. This adjective tunicate is not to be confused with the noun tunicate, which refers to a member of the subphylum Tunicata.
The visceral and parietal pleurae, like all mesothelia, both derive from the lateral plate mesoderms. During the third week of embryogenesis, each lateral mesoderm splits into two layers. The dorsal layer joins overlying somites and ectoderm to form the somatopleure; and the ventral layer joins the underlying endoderm to form the splanchnopleure. The dehiscence of these two layers creates a fluid-filled cavity on each side, and with the ventral infolding and the subsequent midline fusion of the trilaminar disc, forms a pair of intraembryonic coeloms anterolaterally around the gut tube during the fourth week, with the splanchnopleure on the inner cavity wall and the somatopleure on the outer cavity wall.
Ciona intestinalis (sometimes known by the common name of vase tunicate) is an ascidian (sea squirt), a tunicate with very soft tunic. Its Latin name literally means "pillar of intestines", referring to the fact that its body is a soft, translucent column-like structure, resembling a mass of intestines sprouting from a rock. It is a globally distributed cosmopolitan species. Since Linnaeus described the species, Ciona intestinalis has been used as a model invertebrate chordate in developmental biology and genomics.
The abdomen has nine segments, and no cerci.There is often considerable variation in the appearance of individuals within the same species. Many have no wings or ovipositors, and may have a different shape to the thorax. Other, more subtle, variations are also known, such as changes to the development of the setae.
It is accompanied by venae comitantes (accompanying veins). It gives branches to the muscles of the anterior compartment.
|
What is the common measure of how hot or cold something is?
|
[
"variation",
"precipitation",
"weight",
"temperature"
] |
D
|
temperature: A measure of the average kinetic energy of the particles in matter. In everyday usage, temperature is how hot or cold an object is.
Temperature is a measure of a quality of a state of a material. The quality may be regarded as a more abstract entity than any particular temperature scale that measures it, and is called hotness by some writers. The quality of hotness refers to the state of material only in a particular locality, and in general, apart from bodies held in a steady state of thermodynamic equilibrium, hotness varies from place to place. It is not necessarily the case that a material in a particular place is in a state that is steady and nearly homogeneous enough to allow it to have a well-defined hotness or temperature.
This is a list of the thermal effusivity of some common substances, evaluated at room temperature unless otherwise indicated. (*) minimal convection
A rectal or vaginal measurement taken directly inside the body cavity is typically slightly higher than oral measurement, and oral measurement is somewhat higher than skin measurement. Other places, such as under the arm or in the ear, produce different typical temperatures. While some people think of these averages as representing normal or ideal measurements, a wide range of temperatures has been found in healthy people.
Thermographic camera uses a microbolometer for detection of heat radiation.See also Temperature measurement and Category:Thermometers. More technically related may be seen thermal analysis methods in materials science. For the ranges of temperature-values see: Orders of magnitude (temperature)
In the United States, the Fahrenheit scale is the most widely used. On this scale the freezing point of water corresponds to 32 °F and the boiling point to 212 °F. The Rankine scale, still used in fields of chemical engineering in the US, is an absolute scale based on the Fahrenheit increment.
|
Aquatic biomes in the ocean are called what?
|
[
"aquiomes",
"tundra",
"water biomes",
"marine biomes"
] |
D
|
Aquatic biomes in the ocean are called marine biomes.
Marine biogeochemical cycles are biogeochemical cycles that occur within marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. These biogeochemical cycles are the pathways chemical substances and elements move through within the marine environment. In addition, substances and elements can be imported into or exported from the marine environment. These imports and exports can occur as exchanges with the atmosphere above, the ocean floor below, or as runoff from the land.
The living components of an ecosystem are called the biotic components. Streams have numerous types of biotic organisms that live in them, including bacteria, primary producers, insects and other invertebrates, as well as fish and other vertebrates.
Submarine earthquakes arising from tectonic plate movements under the oceans can lead to destructive tsunamis, as can volcanoes, huge landslides, or the impact of large meteorites. A wide variety of organisms, including bacteria, protists, algae, plants, fungi, and animals, lives in the seas, which offers a wide range of marine habitats and ecosystems, ranging vertically from the sunlit surface and shoreline to the great depths and pressures of the cold, dark abyssal zone, and in latitude from the cold waters under polar ice caps to the warm waters of coral reefs in tropical regions. Many of the major groups of organisms evolved in the sea and life may have started there.
In the ocean, the subtropical gyres north and south of the equator are regions in which the nutrients required for phytoplankton growth (for instance, nitrate, phosphate and silicic acid) are strongly depleted all year round. These areas are described as oligotrophic and exhibit low surface chlorophyll. They are occasionally described as "ocean deserts".
As inhabitants of the largest environment on Earth, microbial marine systems drive changes in every global system. Microbes are responsible for virtually all the photosynthesis that occurs in the ocean, as well as the cycling of carbon, nitrogen, phosphorus and other nutrients and trace elements.Microscopic life undersea is incredibly diverse and still poorly understood. For example, the role of viruses in marine ecosystems is barely being explored even in the beginning of the 21st century.The role of phytoplankton is better understood due to their critical position as the most numerous primary producers on Earth. Phytoplankton are categorized into cyanobacteria (also called blue-green algae/bacteria), various types of algae (red, green, brown, and yellow-green), diatoms, dinoflagellates, euglenoids, coccolithophorids, cryptomonads, chrysophytes, chlorophytes, prasinophytes, and silicoflagellates.
|
Oxygen reaches what veinless part of the eye by diffusing through its tear layer?
|
[
"retina",
"cornea",
"pupil",
"membranes"
] |
B
|
12.7 Molecular Transport Phenomena: Diffusion, Osmosis, and Related Processes 62. You can smell perfume very shortly after opening the bottle. To show that it is not reaching your nose by diffusion, calculate the average distance a perfume molecule moves in one second in air, given its diffusion constant D to be 1.00×10 –6 m 2 /s . What is the ratio of the average distances that oxygen will diffuse in a given time in air and water? Why is this distance less in water (equivalently, why is D less in water)? 64. Oxygen reaches the veinless cornea of the eye by diffusing through its tear layer, which is 0.500-mm thick. How long does it take the average oxygen molecule to do this? 65. (a) Find the average time required for an oxygen molecule to diffuse through a 0.200-mm-thick tear layer on the cornea. 3 (b) How much time is required to diffuse 0.500 cm of oxygen to the cornea if its surface area is 1.00 cm 2 ? 66. Suppose hydrogen and oxygen are diffusing through air. A small amount of each is released simultaneously. How much time passes before the hydrogen is 1.00 s ahead of the oxygen? Such differences in arrival times are used as an analytical tool in gas chromatography.
The movement of the eye is controlled by six distinct extraocular muscles, a superior, an inferior, a medial and a lateral rectus, as well as a superior and an inferior oblique. The superior ophthalmic vein is a sigmoidal vessel along the superior margin of the orbital canal that drains deoxygenated blood from surrounding musculature. The ophthalmic artery is a crucial structure in the orbit, as it is often the only source of collateral blood to the brain in cases of large internal carotid infarcts, as it is a collateral pathway to the circle of Willis.
Fine particles can be bacteria, but also simple dust which can cause irritation of the eye, and lead to tears and subsequent blurred vision.In many species, the eyes are inset in the portion of the skull known as the orbits or eyesockets. This placement of the eyes helps to protect them from injury. For some, the focal fields of the two eyes overlap, providing them with binocular vision. Although most animals have some degree of binocular vision the amount of overlap largely depends on behavioural requirements. In humans, the eyebrows redirect flowing substances (such as rainwater or sweat) away from the eye.
Eye morphogenesis begins with the evagination, or outgrowth, of the optic grooves or sulci. These two grooves in the neural folds transform into optic vesicles with the closure of the neural tube. The optic vesicles then develop into the optic cup with the inner layer forming the retina and the outer portion forming the retinal pigment epithelium. The middle portion of the optic cup develops into the ciliary body and iris. During the invagination of the optic cup, the ectoderm begins to thicken and form the lens placode, which eventually separates from the ectoderm to form the lens vesicle at the open end of the optic cup.Further differentiation and mechanical rearrangement of cells in and around the optic cup gives rise to the fully developed eye.
The eyes were placed anterolaterally and rose slightly from the surface of the prosoma, with the left eye being the only one preserved. While segments 1-4 are complete, segments 5-10 are partially destroyed. The first ten segments are all alike, overlapping each other almost half the length in each segment.
The nasolacrimal duct (also called the tear duct) carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. The opening of the nasolacrimal duct into the inferior nasal meatus of the nasal cavity is partially covered by a mucosal fold (valve of Hasner or plica lacrimalis).Excess tears flow through the nasolacrimal duct which drains into the inferior nasal meatus.
|
Compound light microscopes use lenses to do what?
|
[
"stop light",
"twist light",
"focus light",
"burn light"
] |
C
|
human body system that includes all the muscles of the body.
This uses a wide field of illumination. To provide magnification, a diverging beam is incident on the specimen. An out-of-focus image, which appears as a Fresnel interference pattern, is projected onto the detector. The illumination must have phase distortions in it, often provided by a diffuser that scrambles the phase of the incident wave before it reaches the specimen, otherwise the image remains constant as the specimen is moved, so there is no new ptychographical information from one position to the next. In the electron microscope, a lens can be used to map the magnified Fresnel image onto the detector.
Single micro-lenses are used to couple light to optical fibres; microlens arrays are often used to increase the light collection efficiency of CCD arrays and CMOS sensors, to collect and focus light that would have otherwise fallen onto the non-sensitive areas of the sensor. Micro-lens arrays are also used in some digital projectors, to focus light to the active areas of the LCD used to generate the image to be projected. Current research also relies on micro-lenses of various types to act as concentrators for high efficiency photovoltaics for electricity production.Combinations of microlens arrays have been designed that have novel imaging properties, such as the ability to form an image at unit magnification and not inverted as is the case with conventional lenses. Micro-lens arrays have been developed to form compact imaging devices for applications such as photocopiers and mobile-phone cameras.
This type of metamaterials-based lens, paired with a conventional optical lens is therefore able to reveal patterns too small to be discerned with an ordinary optical microscope. In one experiment, the lens was able to distinguish two 35-nanometer lines etched 150 nanometers apart. Without the metamaterials, the microscope showed only one thick line.In a control experiment, the line pair object was imaged without the hyperlens.
In 1610, he used a telescope at close range to magnify the parts of insects. By 1624, Galileo had used a compound microscope.
Single lenses have a variety of applications including photographic lenses, corrective lenses, and magnifying glasses while single mirrors are used in parabolic reflectors and rear-view mirrors. Combining a number of mirrors, prisms, and lenses produces compound optical instruments which have practical uses. For example, a periscope is simply two plane mirrors aligned to allow for viewing around obstructions.
|
What are the "code words" of the genetic code?
|
[
"nucleotides",
"lipids",
"polymers",
"codons"
] |
D
|
Reading the Genetic Code. The genetic code is read three bases at a time. Codons are the code words of the genetic code. Which amino acid does codon 2 in the drawing stand for?.
Variant genetic codes used by an organism can be inferred by identifying highly conserved genes encoded in that genome, and comparing its codon usage to the amino acids in homologous proteins of other organisms. For example, the program FACIL infers a genetic code by searching which amino acids in homologous protein domains are most often aligned to every codon. The resulting amino acid (or stop codon) probabilities for each codon are displayed in a genetic code logo.As of January 2022, the most complete survey of genetic codes is done by Shulgina and Eddy, who screened 250,000 prokaryotic genomes using their Codetta tool. This tool uses a similar approach to FACIL with a larger Pfam database. Despite the NCBI already providing 33 translation tables, the authors were able to find new 5 genetic code variations (corroborated by tRNA mutations) and correct several misattributions.
The nuclear genetic code is flexible as illustrated by variant genetic codes that reassign standard stop codons to amino acids.
Genes are made from a long molecule called DNA, which is copied and inherited across generations. DNA is made of simple units that line up in a particular order within it, carrying genetic information. The language used by DNA is called genetic code, which lets organisms read the information in the genes.
A codon table can be used to translate a genetic code into a sequence of amino acids. The standard genetic code is traditionally represented as an RNA codon table, because when proteins are made in a cell by ribosomes, it is messenger RNA (mRNA) that directs protein synthesis. The mRNA sequence is determined by the sequence of genomic DNA. In this context, the standard genetic code is referred to as translation table 1.
The ciliate, dasycladacean and Hexamita nuclear code (translation table 6) is a genetic code used by certain ciliate, dasycladacean and Hexamita species. The ciliate macronuclear code has not been determined completely. The codon UAA is known to code for Gln only in the Oxytrichidae.
|
What processes allow for the greatest range of rotation within the vertebral column and facilitate the movement of the head?
|
[
"vertical",
"articular",
"lateral",
"anterior"
] |
B
|
articular processes allow for the greatest range of rotation within the vertebral column. The lumbar region allows for considerable extension, flexion, and lateral flexion, but the orientation of the articular processes largely prohibits rotation. The articulations formed between the skull, the atlas (C1 vertebra), and the axis (C2 vertebra) differ from the articulations in other vertebral areas and play important roles in movement of the head. The atlanto-occipital joint is formed by the articulations between the superior articular processes of the atlas and the occipital condyles on the base of the skull. This articulation has a pronounced U-shaped curvature, oriented along the anterior-posterior axis. This allows the skull to rock forward and backward, producing flexion and extension of the head. This moves the head up and down, as when shaking your head “yes. ” The atlantoaxial joint, between the atlas and axis, consists of three articulations. The paired superior articular processes of the axis articulate with the inferior articular processes of the atlas. These articulating surfaces are relatively flat and oriented horizontally. The third articulation is the pivot joint formed between the dens, which projects upward from the body of the axis, and the inner aspect of the anterior arch of the atlas (Figure 9.14). A strong ligament passes posterior to the dens to hold it in position against the anterior arch. These articulations allow the atlas to rotate on top of the axis, moving the head toward the right or left, as when shaking your head “no.
These steps are known as head tilt, chin lift, and jaw thrust, respectively. If a neck or spinal injury is suspected, the provider should avoid performing this maneuver as further nervous system damage may occur. The cervical spine should be stabilized, if possible, by using either manual stabilization of the head and neck by a provider or applying a C-collar.
The horizontal SCC handles head rotations about a vertical axis (e.g. looking side to side), the superior SCC handles head movement about a lateral axis (e.g. head to shoulder), and the posterior SCC handles head rotation about a rostral-caudal axis (e.g. nodding). SCC sends adaptive signals, unlike the two otolith organs, the saccule and utricle, whose signals do not adapt over time.A shift in the otolithic membrane that stimulates the cilia is considered the state of the body until the cilia are once again stimulated. For example, lying down stimulates cilia and standing up stimulates cilia, however, for the time spent lying the signal that you are lying remains active, even though the membrane resets.
Firm pressure is applied at the base of the skull, along with a sharp pinching and twisting of the thumb and forefinger. At the same time, the tail is pulled backward. This severs the spinal cord at the base of the brain or within the cervical spine area (the upper third of the neck). According to the Canadian Council on Animal Care (CCAC), cervical dislocation is normally only conducted on small animals.
The inner ligaments limit rotation of the head and are very strong. The weak apical ligament lies in front of the upper longitudinal bone of the cruciform ligament and joins the apex of the deltoid peg to the anterior margin of the foramen magnum. It is the fibrous remnant of the notochord.
In a standing posture, when the pelvis is tilted posteriorly, the ligament is twisted and tense, which prevents the trunk from falling backwards and the posture is maintained without the need for muscular activity. In this position the ligament also keeps the femoral head pressed into the acetabulum.As the hip flexes, the tension in the ligament is reduced and the amount of possible rotations in the hip joint is increased, which permits the pelvis to tilt backwards into its sitting angle. Lateral rotation and adduction in the hip joint is controlled by the strong transversal part, while the descending part limits medial rotation.Turnout used in the classical ballet style requires a great deal of flexibility in this ligament.
|
What property does coulomb electric force depend upon?
|
[
"electric case",
"electric neutral",
"electric charge",
"electric half"
] |
C
|
Electromagnetism is associated with charge and is a fundamental force of nature, like gravity. If charges are static, the only manifestation of electromagnetism is the Coulomb electric force. In the same way that gravitational force depends on mass, the Coulomb electric force depends on the property known as electric charge. Like gravity, the Coulomb electric Force decreases with the square of the distance. The Coulomb electric force is responsible for many of the forces we discussed previously: the normal force, contact forces such as friction, and so on - all of these forces arise in the mutual attraction and repulsion of charged particles.
For example, the electric charge of a particle is a coupling constant that characterizes an interaction with two charge-carrying fields and one photon field (hence the common Feynman diagram with two arrows and one wavy line). Since photons mediate the electromagnetic force, this coupling determines how strongly electrons feel such a force, and has its value fixed by experiment.
Despite various efforts, a velocity-dependent and/or acceleration-dependent correction to Coulomb's law has never been observed, as described in the next section. Moreover, Hermann von Helmholtz observed that Weber electrodynamics predicted that under certain configurations charges can act as if they had negative inertial mass, which has also never been observed. (Some scientists have, however, disputed Helmholtz's argument.)
One example is utilization of electrostatic force that can be applied in: Dielectric Elastomer Actuators (DEAs) that use high-voltage electric field in order to change its shape (example of working DEA). These actuators can produce high forces, have high specific power (W kg−1), produce large strains (>1000%), possess high energy density (>3 MJ m−3), exhibit self-sensing, and achieve fast actuation rates (10 ms - 1 s). However, the need for high-voltages quickly becomes the limiting factor in the potential practical applications.
He used a torsion balance to study the repulsion and attraction forces of charged particles, and determined that the magnitude of the electric force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. The torsion balance consists of a bar suspended from its middle by a thin fiber. The fiber acts as a very weak torsion spring.
Therefore, if one derives the unit of charge from the Coulomb's law by setting k C = 1 {\displaystyle k_{\rm {C}}=1} then Ampère's force law will contain a factor 2 / c 2 . {\displaystyle 2/c^{2}.} Alternatively, deriving the unit of current, and therefore the unit of charge, from the Ampère's force law by setting k A = 1 {\displaystyle k_{\rm {A}}=1} or k A = 1 / 2 , {\displaystyle k_{\rm {A}}=1/2,} will lead to a constant factor in the Coulomb's law.
|
What is the process of changing something from a gas to a liquid?
|
[
"sublimation",
"condensation",
"combustion",
"fermentation"
] |
B
|
Condensation is the change of state from a gas to a liquid.
One of the main methods of direct conversion of coal to liquids by hydrogenation process is the Bergius process. In this process, coal is liquefied by heating in the presence of hydrogen gas (hydrogenation). Dry coal is mixed with heavy oil recycled from the process. Catalysts are typically added to the mixture.
When a substance undergoes a phase transition (changes from one state of matter to another) it usually either takes up or releases energy. For example, when water evaporates, the increase in kinetic energy as the evaporating molecules escape the attractive forces of the liquid is reflected in a decrease in temperature. The energy required to induce the phase transition is taken from the internal thermal energy of the water, which cools the liquid to a lower temperature; hence evaporation is useful for cooling. See Enthalpy of vaporization. The reverse process, condensation, releases heat. The heat energy, or enthalpy, associated with a solid to liquid transition is the enthalpy of fusion and that associated with a solid to gas transition is the enthalpy of sublimation.
Apart from chemical refining, bubbling, i.e. direct blowing of gas into the melt is used. Less common are methods like ultrasonic refining or low-pressure refining. == References ==
Pyrolysis is thermochemical conversion process in which the feeding material is converted into char, oil and combustible gas in an inert atmosphere (complete absence of oxidizing agent).
Further compression of the surfactant molecules on the surface shows behavior similar to phase transitions. The ‘gas’ gets compressed into ‘liquid’ and ultimately into a perfectly closed packed array of the surfactant molecules on the surface corresponding to a ‘solid’ state. The liquid state is usually separated in the liquid-expanded and liquid-condensed states.
|
What are the two divisions of vascular plants?
|
[
"root and seed",
"seedless and semi-seeded",
"seedless and seed",
"aquatic and terrestrial"
] |
C
|
The most basic division of living plants is between nonvascular and vascular plants. Vascular plants are further divided into seedless and seed plants. Seed plants called gymnosperms produce seeds in cones. Seed plants called angiosperms produce seeds in the ovaries of flowers.
A vascular plant begins from a single celled zygote, formed by fertilisation of an egg cell by a sperm cell. From that point, it begins to divide to form a plant embryo through the process of embryogenesis. As this happens, the resulting cells will organise so that one end becomes the first root, while the other end forms the tip of the shoot. In seed plants, the embryo will develop one or more "seed leaves" (cotyledons).
A major difference between vascular and non-vascular plants is that in the latter the haploid gametophyte is the more visible and longer-lived stage. In vascular plants, the diploid sporophyte has evolved as the dominant and visible phase of the life cycle. In seed plants and some other groups of vascular plants the gametophyte phases are strongly reduced in size and contained within the pollen and ovules. The female gametophyte is entirely contained within the sporophyte's tissues, while the male gametophyte in its pollen grain is released and transferred by wind or animal vectors to fertilize the ovules.
The functions of the stem are to raise and support the leaves and reproductive organs above the level of the soil, to facilitate absorption of light for photosynthesis, gas exchange, water exchange (transpiration), pollination, and seed dispersal. The stem also serves as a conduit, from roots to overhead structures, for water and other growth-enhancing substances. These conduits consist of specialised tissues known as vascular bundles, which give the name "vascular plants" to the angiosperms.
(eds.). Catalogue of the vascular plants of Ecuador = Catálogo de las plantas vasculares del Ecuador (PDF). St.
This is a contrast to on land, where most primary production is performed by vascular plants. Algae ranges from single floating cells to attached seaweeds, while vascular plants are represented in the ocean by groups such as the seagrasses and the mangroves. Larger producers, such as seagrasses and seaweeds, are mostly confined to the littoral zone and shallow waters, where they attach to the underlying substrate and are still within the photic zone.
|
What contains carbon, hydrogen, and oxygen in a ratio of 1:2:1?
|
[
"helium",
"carbohydrate",
"sodium",
"magnesium"
] |
B
|
The term carbohydrate comes from the fact that the majority contain carbon, hydrogen, and oxygen in a ratio of 1:2:1, making for an empirical formula of CH 2 O. This is somewhat misleading because the molecules are not actually hydrates of carbon at all. Carbohydrates are monomers and polymers of aldehydes and ketones that have multiple hydroxyl groups attached.
The large amount of neutral hydrogen found in the damped Lyman-alpha systems is thought to dominate the cosmological baryonic density of the universe up to a redshift of z = 4.Under ordinary conditions on Earth, elemental hydrogen exists as the diatomic gas, H2. Hydrogen gas is very rare in the Earth's atmosphere (around 0.53 ppm on a molar basis) because of its light weight, which enables it to escape from the atmosphere more rapidly than heavier gases. However, hydrogen is the third most abundant element on the Earth's surface, mostly in the form of chemical compounds such as hydrocarbons and water.A molecular form called protonated molecular hydrogen (H+3) is found in the interstellar medium, where it is generated by ionization of molecular hydrogen from cosmic rays.
Hundreds of diatomic molecules have been identified in the environment of the Earth, in the laboratory, and in interstellar space. About 99% of the Earth's atmosphere is composed of two species of diatomic molecules: nitrogen (78%) and oxygen (21%). The natural abundance of hydrogen (H2) in the Earth's atmosphere is only of the order of parts per million, but H2 is the most abundant diatomic molecule in the universe. The interstellar medium is dominated by hydrogen atoms.
This is a partial list of molecules that contain 23 carbon atoms.
The recent advancement in the field of stable isotope geochemistry is the study of isotopic structure of minerals and molecules. This requires study of molecules with high resolutions looking at bonding scenario (how heavy isotopes are bonded to each other)- leading to knowledge of stability of molecule depending on its isotopic structure. Oxygen has three stable isotopes (16O, 17O and 18O) and Carbon has two (13C, 12C). A 12C16O2 molecule (composed only with most abundant isotopes of constituent elements) is called a 'monoisotopic' species.
Carbon has three naturally occurring isotopes. About 99% of carbon on Earth is carbon-12 (12C), about 1% is carbon-13 (13C), and a trace amount is carbon-14 (14C). The 12C and 13C isotopes are stable, while 14C decays radioactively to nitrogen-14 (14N) with a half-life of 5730 years. 14C on Earth is produced nearly exclusively by the interaction of cosmic radiation with the upper atmosphere.
|
During interphase of what process, each chromosome is duplicated, and the sister chromatids formed during synthesis are held together at the centromere region by cohesin proteins?
|
[
"mitosis",
"apoptosis",
"digestion",
"meiosis"
] |
D
|
Chapter 11 1 Figure 11.9 Yes, it will be able to reproduce asexually. 2 C 4 D 6 C 8 C 10 C 12 B 14 During the meiotic interphase, each chromosome is duplicated. The sister chromatids that are formed during synthesis are held together at the centromere region by cohesin proteins. All chromosomes are attached to the nuclear envelope by their tips. As the cell enters prophase I, the nuclear envelope begins to fragment, and the proteins holding homologous chromosomes locate each other. The four sister chromatids align lengthwise, and a protein lattice called the synaptonemal complex is formed between them to bind them together. The synaptonemal complex facilitates crossover between non-sister chromatids, which is observed as chiasmata along the length of the chromosome. As prophase I progresses, the synaptonemal complex breaks down and the sister chromatids become free, except where they are attached by chiasmata. At this stage, the four chromatids are visible in each homologous pairing and are called a tetrad. 16 In metaphase I, the homologous chromosomes line up at the metaphase plate. In anaphase I, the homologous chromosomes are pulled apart and move to opposite poles. Sister chromatids are not separated until meiosis II. The fused kinetochore formed during meiosis I ensures that each spindle microtubule that binds to the tetrad will attach to both sister chromatids. 18 a. Crossover occurs in prophase I between non-sister homologous chromosomes. Segments of DNA are exchanged between maternally derived and paternally derived chromosomes, and new gene combinations are formed. Random alignment during metaphase I leads to gametes that have a mixture of maternal and paternal chromosomes. Fertilization is random, in that any two gametes can fuse.
As shown by Uhlmann et al., during the attachment of chromosomes to the mitotic spindle the chromatids remain paired because cohesion between the sisters prevents separation. Cohesion is established during DNA replication and depends on cohesin, which is a multisubunit complex composed of Scc1, Scc3, Smc2, and Smc3.
Synthesis (S) phase: The genetic material is replicated; each of the cell's chromosomes duplicates to become two identical sister chromatids attached at a centromere. This replication does not change the ploidy of the cell since the centromere number remains the same.
The two sister chromatids are initially bound together by the cohesin complex until the beginning of anaphase, at which point the mitotic spindle pulls the two sister chromatids apart, leaving each of the two daughter cells with an equivalent number of sister chromatids. The proteins that bind the two sister chromatids, disallowing any premature sister chromatid separation, are a part of the cohesin protein family. One of these cohesin proteins crucial for sister chromatid cohesion is Scc1. Esp1 is a separase protein that cleaves the cohesin subunit Scc1 (RAD21), allowing sister chromatids to separate at the onset of anaphase during mitosis.
Homologous chromosomes are separated in the first division (meiosis I), and sister chromatids are separated in the second division (meiosis II). Both of these cell division cycles are used in the process of sexual reproduction at some point in their life cycle. Both are believed to be present in the last eukaryotic common ancestor.
Cohesin rings, especially in budding yeast, are also located in the region surrounding the centromere. Two hypotheses may explain this: the presence of repetitive heterochromatic DNA in centromeres and the presence of chromosome-associated proteins. For example, Schizosaccharomyces pombe have multiple copies of specific heterochromatic DNA whose involvement in cohesion binding has been proven. Budding yeast lacks repetitive sequences and, therefore, requires a different mechanism for cohesion binding. Evidence suggests that binding of cohesin to the budding yeast centromere region depends on chromosome-associated proteins of the kinetochore that mediate cohesion association to pericentric regions (the kinetochore is an enhancer of pericentric cohesin binding).
|
Like animals, cyanobacteria possess what kind of biological rhythm?
|
[
"brain rhythm",
"circadian rhythm",
"music rhythm",
"variable rhythm"
] |
B
|
Golden studies the endogenous rhythms of cyanobacteria, a group of photosynthetic bacteria known to have circadian clocks. She transformed Synechococcus elongatus, one of the better studied cyanobacteria species, with a luciferase reporter gene and showed circadian rhythm in bioluminescence. This reporter system was used to discover three key proteins related to the cyanobacterial clock: KaiA, KaiB, and KaiC. In collaboration with Carl H. Johnson and Takao Kondo, she demonstrated and described the molecular mechanism regulating circadian rhythms in S. elongatus PCC 7942, the only model organism for a prokaryotic circadian clock. Susan Golden identified genes in the S. elongatus genome that contribute to circadian rhythm through mutational screens using transposons to disrupt genes and their function. In one mutation screen study, nineteen mutations were identified and mapped to the three kai genes; Inactivation of any single kai gene reduced kaiBC-promoter activity and abolished the circadian rhythm of expression of KaiA and KaiB.
In molecular biology, the cyanobacterial clock proteins are the main circadian regulator in cyanobacteria. The cyanobacterial clock proteins comprise three proteins: KaiA, KaiB and KaiC. The kaiABC complex may act as a promoter-nonspecific transcription regulator that represses transcription, possibly by acting on the state of chromosome compaction. This complex is expressed from a KaiABC operon.
Cyanobacteria have been documented to form symbioses with a large range of eukaryotes in both marine and terrestrial environments. Cyanobionts provide benefit through dissolved organic carbon (DOC) production or nitrogen fixation but vary in function depending on their host. Organisms that depend on cyanobacteria often live in nitrogen-limited, oligotrophic environments and can significantly alter marine composition leading to blooms.
In addition, cyanobacteria-based biofilms can be used as bioreactors to produce a wide range of chemicals, including biofuels like biodiesel and ethanol. However, despite their importance to the history of life on Earth, and their commercial and environmental potentials, there remain basic questions of how filamentous cyanobacteria move, respond to their environment and self-organize into collective patterns and structures.All known cyanobacteria lack flagella; however, many filamentous species move on surfaces by gliding, a form of locomotion where no physical appendages are seen to aid movement. The actual mechanism behind gliding is not fully understood, although over a century has elapsed since its discovery.
They consist of three major components: a central biochemical oscillator with a period of about 24 hours that keeps time; a series of input pathways to this central oscillator to allow entrainment of the clock; a series of output pathways tied to distinct phases of the oscillator that regulate overt rhythms in biochemistry, physiology, and behavior throughout an organism.The clock is reset as an organism senses environmental time cues of which the primary one is light. Circadian oscillators are ubiquitous in tissues of the body where they are synchronized by both endogenous and external signals to regulate transcriptional activity throughout the day in a tissue-specific manner. The circadian clock is intertwined with most cellular metabolic processes and it is affected by organism aging. The basic molecular mechanisms of the biological clock have been defined in vertebrate species, Drosophila melanogaster, plants, fungi, bacteria, and presumably also in Archaea.In 2017, the Nobel Prize in Physiology or Medicine was awarded to Jeffrey C. Hall, Michael Rosbash and Michael W. Young "for their discoveries of molecular mechanisms controlling the circadian rhythm" in fruit flies.
|
The ocean is the largest marine biome. it is a continuous body of salt water that is relatively uniform in chemical composition; it is a weak solution of mineral salts and decayed what?
|
[
"uranium atoms",
"rock shards",
"biological matter",
"metal ores"
] |
C
|
Marine Biomes The ocean is the largest marine biome. It is a continuous body of salt water that is relatively uniform in chemical composition; it is a weak solution of mineral salts and decayed biological matter. Within the ocean, coral reefs are a second kind of marine biome. Estuaries, coastal areas where salt water and fresh water mix, form a third unique marine biome. Ocean The physical diversity of the ocean is a significant influence on plants, animals, and other organisms. The ocean is categorized into different zones based on how far light reaches into the water. Each zone has a distinct group of species adapted to the biotic and abiotic conditions particular to that zone. The intertidal zone, which is the zone between high and low tide, is the oceanic region that is closest to land (Figure 44.21). Generally, most people think of this portion of the ocean as a sandy beach. In some cases, the intertidal zone is indeed a sandy beach, but it can also be rocky or muddy. The intertidal zone is an extremely variable environment because of tides. Organisms are exposed to air and sunlight at low tide and are underwater most of the time, especially during high tide. Therefore, living things that thrive in the intertidal zone are adapted to being dry for long periods of time. The shore of the intertidal zone is also repeatedly struck by waves, and the organisms found there are adapted to withstand damage from the pounding action of the waves (Figure 44.22). The exoskeletons of shoreline crustaceans (such as the shore crab, Carcinus maenas) are tough and protect them from desiccation (drying out) and wave damage. Another consequence of the pounding waves is that few algae and plants establish themselves in the constantly moving rocks, sand, or mud.
Marine biogeochemical cycles are biogeochemical cycles that occur within marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. These biogeochemical cycles are the pathways chemical substances and elements move through within the marine environment. In addition, substances and elements can be imported into or exported from the marine environment. These imports and exports can occur as exchanges with the atmosphere above, the ocean floor below, or as runoff from the land.
Sea water carries oxygen and nutrients to oceanic organisms, which allow them to be planktonic or settled. The dissolved minerals and oxygen flow with currents/circulations.
The viability of species is being disrupted throughout the ocean food web due to changes in ocean chemistry. As the ocean warms, mixing between water layers decreases, resulting in less oxygen and nutrients being available for marine life. : 3
Biogenous sediments come from the remains of living organisms that settle out as sediment when the organisms die. It is the "hard parts" of the organisms that contribute to the sediments; things like shells, teeth or skeletal elements, as these parts are usually mineralized and are more resistant to decomposition than the fleshy "soft parts" that rapidly deteriorate after death.Macroscopic sediments contain large remains, such as skeletons, teeth, or shells of larger organisms. This type of sediment is fairly rare over most of the ocean, as large organisms do not die in enough of a concentrated abundance to allow these remains to accumulate. One exception is around coral reefs; here there is a great abundance of organisms that leave behind their remains, in particular the fragments of the stony skeletons of corals that make up a large percentage of tropical sand.Microscopic sediment consists of the hard parts of microscopic organisms, particularly their shells, or tests.
Vital effects are biological impacts on geochemical records. Many marine organisms, ranging from zooplankton (e.g. foraminifera) to phytoplankton (e.g diatoms) to reef builders (e.g. coral), create shells or skeletons from chemical compounds dissolved in seawater. This process, which is also called biomineralization, therefore records the chemical signature of seawater during the time of shell formation. However, different species have different metabolism and physiology, causing them to create their shells in different ways. These biological distinctions cause species to record slightly different chemical signatures in their shells; these differences are known as vital effects.
|
What two tubes extend from the upper corners of the uterus?
|
[
"fallopian",
"Cervical",
"ovarian",
"ovary"
] |
A
|
Extending from the upper corners of the uterus are the two fallopian tubes . Each tube reaches (but is not attached to) one of the ovaries. The ovary end of the tube has a fringelike structure that moves in waves. The motion sweeps eggs from the ovary into the tube.
The cervix (PL: cervices) or cervix uteri (Latin, "neck of the uterus") is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during pregnancy. The narrow, central cervical canal runs along its entire length, connecting the uterine cavity and the lumen of the vagina. The opening into the uterus is called the internal os, and the opening into the vagina is called the external os.
It will have divided on its journey to form a blastocyst that will implant itself into the lining of the uterus – the endometrium, where it will receive nutrients and develop into the embryo proper and later fetus for the duration of the pregnancy. In the human embryo, the uterus develops from the paramesonephric ducts which fuse into the single organ known as a simplex uterus.
Marsupials have two lateral vaginas and a medial vagina. The "vagina" of monotremes is better understood as a "urogenital sinus". The uterine systems of placental mammals can vary between a duplex, where there are two uteri and cervices which open into the vagina, a bipartite, where two uterine horns have a single cervix that connects to the vagina, a bicornuate, which consists where two uterine horns that are connected distally but separate medially creating a Y-shape, and a simplex, which has a single uterus.
As a result, there may appear to be two openings to the vagina. There may be associated duplications of the more cranial parts of the Müllerian derivatives, a double cervix, and either a uterine septum or uterus didelphys (double uterus). A transverse septum forms during embryogenesis when the Müllerian ducts do not fuse to the urogenital sinus.
The uterus (from Latin uterus, PL: uteri) or womb () is the organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic and fetal development of one or more embryos until birth. The uterus is a hormone-responsive sex organ that contains glands in its lining that secrete uterine milk for embryonic nourishment. The term uterus is also applied to analogous structures in some non-mammalian animals. In the human, the lower end of the uterus is a narrow part known as the isthmus that connects to the cervix, leading to the vagina.
|
What term describes a wave in which particles of the medium vibrate at right angles, or perpendicular, to the direction that the wave travels?
|
[
"drainage wave",
"symmetrical wave",
"transverse wave",
"stimulation wave"
] |
C
|
A transverse wave is a wave in which particles of the medium vibrate at right angles, or perpendicular, to the direction that the wave travels. Another example of a transverse wave is the wave that passes through a rope with you shake one end of the rope up and down, as in the Figure below . The direction of the wave is down the length of the rope away from the hand. The rope itself moves up and down as the wave passes through it. You can watch a video of a transverse wave in a rope at this URL: http://www. youtube. com/watch?v=TZIr9mpERbU .
These occur where waves are formed from the returning backwash of a wave which has previously gone up a steep shoreline or beach, or sometimes reflected from an ocean rockface or wall. They can sometimes form a surfable wave in a direction oblique to, or opposite from the original wave direction. An example was shown in the film Endless Summer, in Tahiti, called 'Ins and Outs'.
The motion of transverse waves, on the other hand, is perpendicular to the propagation direction and is thus less easily propagated through the medium. As a result, longitudinal waves travel more quickly through solids than transverse waves. An example of this can be seen in quartz with an approximate acoustic longitudinal wave velocity of 5965 m/s and transverse wave velocity of 3750 m/s.
The term was coined in 1877 by French mathematician and physicist Joseph Valentin Boussinesq who called these waves 'le clapotis' meaning "the lapping".In the idealized case of "full clapotis" where a purely monotonic incoming wave is completely reflected normal to a solid vertical wall, the standing wave height is twice the height of the incoming waves at a distance of one half wavelength from the wall. In this case, the circular orbits of the water particles in the deep-water wave are converted to purely linear motion, with vertical velocities at the antinodes, and horizontal velocities at the nodes. The standing waves alternately rise and fall in a mirror image pattern, as kinetic energy is converted to potential energy, and vice versa. In his 1907 text, Naval Architecture, Cecil Peabody described this phenomenon: At any instant the profile of the water surface is like that of a trochoidal wave, but the profile instead of appearing to run to the right or left, will grow from a horizontal surface, attain a maximum development, and then flatten out till the surface is again horizontal; immediately another wave profile will form with its crests where the hollows formerly were, will grow and flatten out, etc. If attention is concentrated on a certain crest, it will be seen to grow to its greatest height, die away, and be succeeded in the same place by a hollow, and the interval of time between the successive formations of crests at a given place will be the same as the time of one of the component waves.
Motion of the medium itself. If the medium is moving, this movement may increase or decrease the absolute speed of the sound wave depending on the direction of the movement. For example, sound moving through wind will have its speed of propagation increased by the speed of the wind if the sound and wind are moving in the same direction.
There are two types of body waves, pressure waves or primary waves (P-waves) and shear or secondary waves (S-waves). P-waves are longitudinal waves that involve compression and expansion in the direction that the wave is moving and are always the first waves to appear on a seismogram as they are the fastest moving waves through solids. S-waves are transverse waves that move perpendicular to the direction of propagation.
|
Exemplified by rusty iron, what process is defined as the disintegration of a material due to chemical reactions with other substances in the environment?
|
[
"Metal Breakdown",
"magnesium",
"corrosion",
"extraction"
] |
C
|
Most of us are familiar with rusty iron: metal that has a dark red-brown scale that falls off an object, ultimately weakening it. Although we usually attribute rusting exclusively to iron, this process occurs with many materials. The more formal term for rusting is corrosion. Corrosion is defined as the disintegration of a material due to chemical reactions with other substances in the environment. In many cases, oxygen in the air causes the disintegration. Corrosion is not uniformly destructive. Although the corrosion of iron is generally considered bad, the corrosion of aluminum and copper forms a protective barrier on the surface of the metal, protecting it from further reaction with the environment. Having said that, it has been estimated that as much as 5% of expenditures in the United States apply to fixing problems caused by corrosion. The replacement of structures built with iron, steel, aluminum, and concrete must be performed regularly to keep these structures safe. As an example of what might happen, consider the story of the Silver Bridge on US Interstate 35, connecting West Virginia and Ohio. On December 15, 1967, the 39-year-old bridge collapsed, killing 46 people. The ultimate cause of the collapse was determined to be corrosion of a suspension chain on the Ohio side of the bridge. Corrosion is an example of the type of chemical reaction discussed in this chapter. Although we usually think of corrosion as bad, the reaction it typifies can actually be put to good use. One important type of chemical reaction is the oxidation-reduction reaction, also known as the redox reaction. Although we introduced redox reactions in - ball-ch04, - ball-ch04_s06, it is worth reviewing some basic concepts.
Fixation of iron by hide substance. Industrial and Engineering Chemistry, 20, 632–4. Thomas, A. W., & Mayer, C. W.
A base metal, such as iron (Fe) goes into aqueous solution as positively charged cation, Fe2+. As the metal is oxidized under anaerobic conditions by the protons of water, H+ ions are reduced to form molecular H2. This can be written in the following ways under acidic and neutral conditions respectively: Fe + 2 H+ → Fe2+ + H2Fe + 2 H2O → Fe(OH)2 + H2Usually, a thin film of molecular hydrogen forms on the metal. Sulfate-reducing bacteria oxidize the molecular hydrogen to produce hydrogen sulfide ions (HS−) and water: 4 H2 + SO42− → HS− + 3 H2O + OH−The iron ions partly precipitate to form iron (II) sulfide. Another reaction occurs between iron and water producing iron hydroxide. Fe2+ + HS− → FeS + H+ 3 Fe2+ + 6 H2O → 3 Fe(OH)2 + 6 H+The net equation comes to: 4 Fe + SO42− + H+ + 3 H2O → FeS + 3 Fe(OH)2 + OH−This form of corrosion by sulfate-reducing bacteria can, in this way, be far more harmful than anaerobic corrosion.
In geology, mineralization is the deposition of economically important metals in the formation of ore bodies or "lodes" by various process. The first scientific studies of this process took place in the English county of Cornwall by J.W.Henwood FRS and later by R.W. Fox, FRS.The term can also refer to the process by which waterborne minerals, such as calcium carbonate (calcite), iron oxide (hematite or limonite) or silica (quartz), replace organic material within the body of an organism that has died and was buried by sediments.Mineralization may also refer to the product resulting from the process of mineralization. For example, mineralization (the process) may introduce metals (such as iron) into a rock. That rock may then be referred to as possessing iron mineralization.
Iron ores consist of oxygen and iron atoms bonded together into molecules. To convert it to metallic iron it must be smelted or sent through a direct reduction process to remove the oxygen. Oxygen-iron bonds are strong, and to remove the iron from the oxygen, a stronger elemental bond must be presented to attach to the oxygen. Carbon is used because the strength of a carbon-oxygen bond is greater than that of the iron-oxygen bond, at high temperatures.
In the finishing of steel prior to plating or coating, the steel sheet or rod is passed through pickling baths of sulfuric acid. This treatment produces large quantities of iron(II) sulfate as a by-product. Fe + H2SO4 → FeSO4 + H2Another source of large amounts results from the production of titanium dioxide from ilmenite via the sulfate process. Ferrous sulfate is also prepared commercially by oxidation of pyrite: 2 FeS2 + 7 O2 + 2 H2O → 2 FeSO4 + 2 H2SO4It can be produced by displacement of metals less reactive than Iron from solutions of their sulfate: CuSO4 + Fe → FeSO4 + Cu
|
What is a renewable resource that can take thousand of years to form?
|
[
"sunlight",
"soil",
"wind",
"water"
] |
B
|
Soil is a renewable resource, but it can take thousands of years to form. That’s why people need to do what they can to prevent soil erosion.
Beltratti, A., Chichilnisky, G. and Heal, G., 1998. Sustainable use of renewable resources. In Sustainability: Dynamics and Uncertainty (pp. 49–76). Springer Netherlands.
We must continue changing the way America generates electric power, by even greater use of … solar and wind energy. We must continue investing in new methods of producing ethanol, using everything from wood chips to grasses, to agricultural wastes. ACORE suggests that these reports dispel the commonly held notion that renewable energy cannot supply the energy needs of a growing American economy. But for this to happen, the government would have to commit to long term policies that promote renewable energy.
A comprehensive decarbonization plan describes how to generate enough green energy to replace coal, oil, and natural gas; and takes into consideration factors such as increasing GDP, increasing standard of living, and increasing efficiencies. Each year the world consumes 583 exajoules of heat energy. With 35% efficient turbines, this yields 56000 TWh of electricity yearly. To decarbonize, that amount of electricity must be generated through means with very low CO2 emissions, such as hydroelectric dams, nuclear energy, wind farms and solar parks.
In some cases it will be cheaper to transition to these sources as opposed to continuing to use the current, inefficient, fossil fuels. In addition, electrification with renewable energy is more efficient and therefore leads to significant reductions in primary energy requirements.It would also reduce environmental pollution such as air pollution caused by the burning of fossil fuels, and improve public health, reduce premature mortalities due to pollution and save associated health costs that could amount to trillions of dollars annually. Multiple analyses of decarbonization strategies have found that quantified health benefits can significantly offset the costs of implementing these strategies.Climate change concerns, coupled with the continuing fall in the costs of some renewable energy equipment, such as wind turbines and solar panels, are driving increased use of renewables. New government spending, regulation and policies helped the industry weather the global financial crisis better than many other sectors. As of 2019, however, according to the International Renewable Energy Agency, renewables overall share in the energy mix (including power, heat and transport) needs to grow six times faster, in order to keep the rise in average global temperatures "well below" 2.0 °C (3.6 °F) during the present century, compared to pre-industrial levels.
Renewable energy includes a number of sources and technologies at different stages of commercialization. The International Energy Agency (IEA) has defined three generations of renewable energy technologies, reaching back over 100 years: "First-generation technologies emerged from the industrial revolution at the end of the 19th century and include hydropower, biomass combustion, geothermal power and heat. These technologies are quite widely used. Second-generation technologies include solar heating and cooling, wind power, modern forms of bioenergy, and solar photovoltaics.
|
Impenetrable what underlies the soil of the forest?
|
[
"structure",
"topsoil",
"bedrock",
"groundwater"
] |
C
|
Intact soils harbor many life forms that rely on them. Intact soils generally have very well-defined horizons, or soil profiles. Different organisms may need certain well-defined soil horizons to live, while many trees need well-structured soils free of disturbance to thrive. Some herbaceous plants in northern hardwood forests must have thick duff layers (which are part of the soil profile). Fungal ecosystems are essential for efficient in-situ recycling of nutrients back into the entire ecosystem.
Organic matter tends to accumulate under wet or cold conditions where decomposer activity is impeded by low temperature or excess moisture which results in anaerobic conditions. Conversely, excessive rain and high temperatures of tropical climates enables rapid decomposition of organic matter and leaching of plant nutrients. Forest ecosystems on these soils rely on efficient recycling of nutrients and plant matter by the living plant and microbial biomass to maintain their productivity, a process which is disturbed by human activities. Excessive slope, in particular in the presence of cultivation for the sake of agriculture, may encourage the erosion of the top layer of soil which holds most of the raw organic material that would otherwise eventually become humus.
Forests are studied at a number of organisational levels, from the individual organism to the ecosystem. However, as the term forest connotes an area inhabited by more than one organism, forest ecology most often concentrates on the level of the population, community or ecosystem. Logically, trees are an important component of forest research, but the wide variety of other life forms and abiotic components in most forests means that other elements, such as wildlife or soil nutrients, are also crucial components.Forest ecology shares characteristics and methodological approaches with other areas of terrestrial plant ecology, however, the presence of trees makes forest ecosystems and their study unique in numerous ways due to the potential for a wide variety of forest structures created by the uniquely large size and height of trees compared with other terrestrial plants.
Regardless of its name, the equilibrium stage of primary succession is the highest natural form of development that the environmental factors are capable of producing. The cycles of evolution of soils have very variable durations, between tens, hundreds, or thousands of years for quickly evolving soils (A horizon only) to more than a million years for slowly developing soils. The same soil may achieve several successive steady state conditions during its existence, as exhibited by the Pygmy forest sequence in Mendocino County, California. Soils naturally reach a state of high productivity, from which they naturally degrade as mineral nutrients are removed from the soil system. Thus older soils are more vulnerable to the effects of induced retrogression and degradation.
Environmental interactions such as regulating water supplies, water loos, utilization, contamination, and purification are all affected by the soil. They can filter, buffer, and transform materials between the atmosphere, the plant cover, and the water table. Soil interacts with the environment to transform and decompose waste materials in to new materials.
|
What is the term for when two opposing processes reach the same speed, resulting in no overall change?
|
[
"equilibrium",
"neutralization",
"acceleration",
"homeostasis"
] |
A
|
Imagine you are stranded in a rowboat in the middle of the ocean. Suddenly, your boat springs a small leak, and you need to bail out water. You grab a bucket and begin to bail. After a few minutes, your efforts against the leak keep the water to only about half an inch, but any further bailing doesn’t change the water level; the leak brings in as much water as you bail out. You are at equilibrium. Two opposing processes have reached the same speed, and there is no more overall change in the process. Chemical reactions are like that as well. Most of them come to an equilibrium. The actual position of the equilibrium—whether it favors the reactants or the products—is characteristic of a chemical reaction; it is difficult to see just by looking at the balanced chemical equation. But chemistry has tools to help you understand the equilibrium of chemical reactions—the focus of our study in this chapter. So far in this text, when we present a chemical reaction, we have implicitly assumed that the reaction goes to completion. Indeed, our stoichiometric calculations were based on this; when we asked how much of a product is produced when so much of a reactant reacts, we are assuming that all of a reactant reacts. However, this is usually not the case; many reactions do not go to completion, and many chemists have to deal with that. In this chapter, we will study this phenomenon and see ways in which we can affect the extent of chemical reactions.
If transitions on two inputs arrive at almost the same time, the circuit can go into the wrong state depending on slight differences in the propagation delays of the gates. This is called a race condition. In synchronous circuits this problem is less severe because race conditions can only occur due to inputs from outside the synchronous system, called asynchronous inputs. Although some fully asynchronous digital systems have been built (see below), today asynchronous circuits are typically used in a few critical parts of otherwise synchronous systems where speed is at a premium, such as signal processing circuits.
In some settings, the machine speed is the machine's private information, and we want to incentivize machines to reveal their true speed, that is, we want a truthful mechanism. An important consideration for attaining truthfulness is monotonicity. It means that, if a machine reports a higher speed, and all other inputs remain the same, then the total processing time allocated to the machine weakly increases.
If the primary scenario successfully escalates to other installations nearby, one or more secondary events occur. Escalation from the primary event to the secondary event is called the first-level escalation, while escalation from secondary event to a potential tertiary event is called second-level escalation, and so on. When lower-level event triggers multiple higher-level events, these are called parallel effects. A higher-level event caused by multiple lower-level events is a case of synergistic effects. Time-dependent escalation vectors from different sources and acting at different times may result in a synergic effect over a secondary target; this is called superimposed effects.
Natural process variation, sometimes just called process variation, is the statistical description of natural fluctuations in process outputs.
This is analogous to increasing throughput by increasing bandwidth but leaving latency unchanged. The units usually refer to the "effective" number of transfers, or transfers perceived from "outside" of a system or component, as opposed to the internal speed or rate of the clock of the system.
|
What term describes the number and kinds of species in a location or on the planet?
|
[
"habitat",
"Allopatric speciation",
"biodiversity",
"ecosystem"
] |
C
|
Types of Biodiversity Scientists generally accept that the term biodiversity describes the number and kinds of species in a location or on the planet. Species can be difficult to define, but most biologists still feel comfortable with the concept and are able to identify and count eukaryotic species in most contexts. Biologists have also identified alternate measures of biodiversity, some of which are important for planning how to preserve biodiversity. Genetic diversity is one of those alternate concepts. Genetic diversity or variation is the raw material for adaptation in a species. A species’ future potential for adaptation depends on the genetic diversity held in the genomes of the individuals in populations that make up the species. The same is true for higher taxonomic categories. A genus with very different types of species will have more genetic diversity than a genus with species that look alike and have similar ecologies. If there were a choice between one of these genera of species being preserved, the one with the greatest potential for subsequent.
A type species is both a concept and a practical system that is used in the classification and nomenclature (naming) of animals. The "type species" represents the reference species and thus "definition" for a particular genus name. Whenever a taxon containing multiple species must be divided into more than one genus, the type species automatically assigns the name of the original taxon to one of the resulting new taxa, the one that includes the type species. The term "type species" is regulated in zoological nomenclature by article 42.3 of the International Code of Zoological Nomenclature, which defines a type species as the name-bearing type of the name of a genus or subgenus (a "genus-group name").
Numerous databases attempt to document the diversity of life on earth. A prominent example is the Catalogue of Life, first created in 2001 by Species 2000 and the Integrated Taxonomic Information System. The Catalogue of Life is a collaborative project that aims to document taxonomic categorization of all currently accepted species in the world. The Catalogue of Life provides a consolidated and consistent database for researchers and policymakers to reference.
A botanist wanting to distinguish groups of species may prefer to create a taxon at the rank of section or series to avoid making new combinations, i.e. many new binomial names for the species involved.Examples: Lilium sectio Martagon Rchb. are the Turks' cap lilies Plagiochila aerea Taylor is the type species of Plagiochila sect. Bursatae
In 60% of the cases the type species can be determined in the original publication. The type species is always the original name of the taxon (and not the currently used combination). Example: The correctly cited type species of Locusta Linnaeus, 1758 (Caelifera) is Gryllus migratorius Linnaeus, 1758, not Locusta migratoria (Linnaeus, 1758).Designation and fixation have different meanings.
The evolutionary changes occurring to an organism within its population or within the wider community. exotic species An introduced species not native or endemic to a habitat. extinction The termination of an organism or of a taxon, usually a species, which occurs when the last individual organism of the taxon dies.
|
What energy is stored in a person or object?
|
[
"kinetic energy",
"mechanical energy",
"stored energy",
"potential energy"
] |
D
|
The diver has energy because of her position high above the pool. The type of energy she has is called potential energy. Potential energy is energy that is stored in a person or object. Often, the person or object has potential energy because of its position or shape.
Despite the fact that humans cannot exceed 500 W (0.67 hp) for meaningful amounts of time, the land speed record for human-powered vehicles (unpaced) is 133 km/h (83 mph), as of 2009 on a recumbent bicycle.The most common type of energy source is fuel. External combustion engines can use almost anything that burns as fuel, whilst internal combustion engines and rocket engines are designed to burn a specific fuel, typically gasoline, diesel or ethanol. Another common medium for storing energy is batteries, which have the advantages of being responsive, useful in a wide range of power levels, environmentally friendly, efficient, simple to install, and easy to maintain.
ATP is the only type of usable form of chemical energy for musculoskeletal activity. It is stored in most cells, particularly in muscle cells. Other forms of chemical energy, such as those available from oxygen and food, must be transformed into ATP before they can be utilized by the muscle cells.
Such rapid movement can generate twice this amount in nonhuman animals such as bonobos, and in some small lizards.This energy expenditure is very large compared to the basal resting metabolic rate of the adult human body. This rate varies somewhat with size, gender and age but is typically between 45 W and 85 W. Total energy expenditure (TEE) due to muscular expended energy is much higher and depends upon the average level of physical work and exercise done during the day. Thus exercise, particularly if sustained for very long periods, dominates the energy metabolism of the body. Physical activity energy expenditure correlates strongly with the gender, age, weight, heart rate, and VO2 max of an individual, during physical activity.
The body's circulatory system transports the oxygen to the cells, where cellular respiration takes place.Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide.
This input power can be determined by measuring oxygen uptake, or in the long term food consumption, assuming no change of weight. This includes the power needed just for living, called the basal metabolic rate BMR or roughly the resting metabolic rate.
|
What do we call a peptide hormone composed of nine amino acids that lowers blood pressure?
|
[
"bradykinin",
"angiotensin",
"parcnid",
"bufotenin"
] |
A
|
Bradykinin is a peptide hormone composed of nine amino acids that lowers blood pressure. Its primary structure is arg-pro-pro-gly-phe-ser-pro-phe-arg. Would you expect bradykinin to be positively charged, negatively charged, or neutral at a pH of 6.0? Justify your answer.
This generation consists of two groups of compounds, either peptide analogues of the prosegment of renin or peptide analogues of the amino-terminal part of the substrate angiotensinogen. The drugs in the latter group seemed to be effective in inhibiting renin activity and lowering blood pressure in both animals and humans. Unfortunately, they had to be given parenterally because of poor bioavailability. They also turned out to have short durations of action, low potencies and their ability to lower blood pressure was inadequate. None of these drugs completed clinical investigations.
The neurohypophysis stores and releases two hypothalamic hormones: Oxytocin stimulates powerful uterine contractions, which trigger labour and delivery of an infant, and milk ejection in nursing women. Its release is mediated reflexively by the hypothalamus and represents a positive feedback mechanism. Antidiuretic hormone stimulates the kidney tubules to reabsorb and conserve water, resulting in small volumes of highly concentrated urine and decreased plasma osmolality. Antidiuretic hormone is released in response to high solute concentrations in the blood and inhibited by low solute concentrations in the blood. Hyposecretion results in diabetes insipidus.
The human body is capable of producing eleven amino acids, however, it is unable to produce nine amino acids. These nine amino acids consist of Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. All nine of these amino acids only come from the production of food.
Amino acids with the structure NH+3−CXY−CXY−CO−2, such as β-alanine, a component of carnosine and a few other peptides, are β-amino acids. Ones with the structure NH+3−CXY−CXY−CXY−CO−2 are γ-amino acids, and so on, where X and Y are two substituents (one of which is normally H).
The term is somewhat archaic. A peptidergic agent (or drug) is a chemical which functions to directly modulate the peptide systems in the body or brain. An example is opioidergics, which are neuropeptidergics. A cell-penetrating peptide is a peptide able to penetrate the cell membrane.
|
Which lymphoid organ is situated in the upper chest?
|
[
"thyroid gland",
"spleen",
"pancreas",
"thymus"
] |
D
|
The thymus is located in the upper chest behind the breast bone. It stores and matures lymphocytes.
The deep anterior cervical lymph nodes are found near the middle cricothyroid ligament and the trachea.
In human anatomy, the thoracic duct (also known as the left lymphatic duct, alimentary duct, chyliferous duct, and Van Hoorne's canal) is the larger of the two lymph ducts of the lymphatic system (the other being the right lymphatic duct). The thoracic duct usually begins from the upper aspect of the cisterna chyli, passing out of the abdomen through the aortic hiatus into first the posterior mediastinum and then the superior mediastinum, extending as high up as the root of the neck before descending to drain into the systemic (blood) circulation at the venous angle. The thoracic duct carries chyle, a liquid containing both lymph and emulsified fats, rather than pure lymph. It also collects most of the lymph in the body other than from the right thorax, arm, head, and neck (which are drained by the right lymphatic duct).When the duct ruptures, the resulting flood of liquid into the pleural cavity is known as chylothorax.
A right lymphatic duct that enters directly into the junction of the internal jugular and subclavian veins is uncommon.
The xiphoid process is considered to be at the level of the 9th thoracic vertebra and the T7 dermatome.
The larvae take up residence in the lymphatic vessels and the lung tissue, hindering respiration and causing chest pain as the disease progresses. This disease can be confused with tuberculosis, asthma, or coughs related to roundworms.The disease itself is a result of a complex interplay between several factors: the worm, the endosymbiotic Wolbachia bacteria within the worm, the host's immune response, and the numerous opportunistic infections and disorders that arise. The adult worms live in the human lymphatic system and obstruct the flow of lymph throughout the body; this results in chronic lymphedema, most often noted in the lower torso (typically in the legs and genitals).
|
What is calculated by subtracting the smallest value from the largest value?
|
[
"the range",
"the sample",
"the density",
"the median"
] |
A
|
The range is the total spread of values. It gives you an idea of the variation in the measurements. The range is calculated by subtracting the smallest value from the largest value. For the data in Table above , the range in numbers of vehicles by type is: 150 - 50 = 100.
In the first column, the number by which the biggest number is multiplied by is located. In this example, the number was 8. Only row 8 will be used for the remaining calculations, so the rest of the board has been cleared for clarity in explaining the remaining steps.
round up (or take the ceiling, or round toward positive infinity): y is the smallest integer that is not less than x. y = ceil ( x ) = ⌈ x ⌉ = − ⌊ − x ⌋ {\displaystyle y=\operatorname {ceil} (x)=\left\lceil x\right\rceil =-\left\lfloor -x\right\rfloor } For example, 23.2 gets rounded to 24, and −23.7 gets rounded to −23.
Early examples of these algorithms are primarily decrease and conquer – the original problem is successively broken down into single subproblems, and indeed can be solved iteratively. Binary search, a decrease-and-conquer algorithm where the subproblems are of roughly half the original size, has a long history. While a clear description of the algorithm on computers appeared in 1946 in an article by John Mauchly, the idea of using a sorted list of items to facilitate searching dates back at least as far as Babylonia in 200 BC. Another ancient decrease-and-conquer algorithm is the Euclidean algorithm to compute the greatest common divisor of two numbers by reducing the numbers to smaller and smaller equivalent subproblems, which dates to several centuries BC.
The IEEE floating-point standard (IEEE 754) specifies a positive and a negative infinity value (and also indefinite values). These are defined as the result of arithmetic overflow, division by zero, and other exceptional operations.Some programming languages, such as Java and J, allow the programmer an explicit access to the positive and negative infinity values as language constants. These can be used as greatest and least elements, as they compare (respectively) greater than or less than all other values. They have uses as sentinel values in algorithms involving sorting, searching, or windowing.In languages that do not have greatest and least elements, but do allow overloading of relational operators, it is possible for a programmer to create the greatest and least elements. In languages that do not provide explicit access to such values from the initial state of the program, but do implement the floating-point data type, the infinity values may still be accessible and usable as the result of certain operations.In programming, an infinite loop is a loop whose exit condition is never satisfied, thus executing indefinitely.
Here is an example of this sort algorithm sorting five elements: (Nothing appears changed on these last two lines because the last two numbers were already in order.) Selection sort can also be used on list structures that make add and remove efficient, such as a linked list. In this case it is more common to remove the minimum element from the remainder of the list, and then insert it at the end of the values sorted so far. For example: arr = 64 25 12 22 11 // Find the minimum element in arr // and place it at beginning 11 25 12 22 64 // Find the minimum element in arr // and place it at beginning of arr 11 12 25 22 64 // Find the minimum element in arr // and place it at beginning of arr 11 12 22 25 64 // Find the minimum element in arr // and place it at beginning of arr 11 12 22 25 64
|
Birds actually have two basic types of feathers: flight feathers and?
|
[
"colorful plumes",
"down feathers",
"landing feathers",
"shed feathers"
] |
B
|
Feathers help birds fly and also provide insulation and serve other purposes. Birds actually have two basic types of feathers: flight feathers and down feathers. Both are shown in Figure below . Flight feathers are long, stiff, and waterproof. They provide lift and air resistance without adding weight. Down feathers are short and fluffy. They trap air next to a bird’s skin for insulation.
Feathers are a feature characteristic of birds (though also present in some dinosaurs not currently considered to be true birds). They facilitate flight, provide insulation that aids in thermoregulation, and are used in display, camouflage, and signalling. There are several types of feathers, each serving its own set of purposes. Feathers are epidermal growths attached to the skin and arise only in specific tracts of skin called pterylae.
Feathers are sometimes referred to as “elaborate reptile scales” just as birds are sometimes viewed as a subset of reptiles instead of their own category. Although this is a simplification, it originates from bird's homology with reptiles. Birds evolved from fast bipedal dinosaurs, but feathers evolved before them, and not for flying as what was originally thought. The theory of feathers evolving for flight unraveled in the 1970s when theropod dinosaurs (some common theropods were Tyrannosaurus rex and Velociraptors) were discovered to have feathers.
Furthermore, the initial five secondary feathers have a bright red speculum on the edge of the feathers. The wing coverts, the underside of the flight feathers, and the tail are green while the tail is tipped with a yellowish colouring similar to that of the cheeks and ear coverts. Their beak, orbital rings, and legs are a pale brown-grey colouring.
Secondary feathers remain close together in flight (they cannot be individually separated like the primaries can) and help to provide lift by creating the airfoil shape of the bird's wing. Secondaries tend to be shorter and broader than primaries, with blunter ends. They vary in number from six in hummingbirds, to as many as 40 in some species of albatross.
Their plumage differs slightly by subspecies, but is generally dark to black for males, with buff to cream highlights, and generally drab brown for females. The feathers are quite iridescent and can take on distinct reddish/copper hues in sunlight. Their feathers are well defined with broad, square ends, giving the bird the appearance of being covered in scales.
|
What is the name for the process of charging an object by touching it with another charged object?
|
[
"charging by connection",
"charging by convection",
"charging by conduction",
"charging by transfer"
] |
C
|
Charging an object by touching it with another charged object is called charging by conduction. By bringing a charged object into contact with an uncharged object, some electrons will migrate to even out the charge on both objects. Charging by conduction gives the previously uncharged object a permanent charge. An uncharged object can also be charged using a method called charging by induction . This process allows a change in charge without actually touching the charged and uncharged objects to each other. Imagine a negatively charged rod held near the knob, but not touching. If we place a finger on the knob, some of the electrons will escape into our body, instead of down the stem and into the leaves. When both our finger and the negatively charged rod are removed, the previously uncharged electroscope now has a slight positive charge. It was charged by induction. Notice that charging by induction causes the newly charged object to have the opposite charge as the originally charged object, while charging by conduction gives them both the same charge.
An electric charge can be positive or negative — objects with a positive charge repel other positively charged objects, thereby causing them to push away from each other, while a positively charged object would attract to a negatively charged object, thereby causing the two to draw together. Experiments showing electrostatic sorting in action can help make the process more clear. To exhibit electrostatic separation at home, an experiment can be conducted using peanuts that are still in their shells.
Conductive charging is conductive power transfer that replaces the conductive wires between the charger and the charged device with conductive contacts. Charging infrastructure in the form of a board or rail delivers the power to a charging device equipped with an appropriate receiver, or pickup. When the infrastructure recognizes a valid receiver it powers on, and power is transferred.
Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber, ἤλεκτρον (ḗlektron), was thus the source of the word 'electricity'. Electrostatic phenomena arise from the forces that electric charges exert on each other.
This process is called solvation. The presence of these free ions makes aqueous ionic compound solutions good conductors of electricity. The same occurs when the compounds are heated above their melting point, i.e., they are melted. This process is known as ionization.
The Pre can be charged either using the supplied MicroUSB cable, or by using an optional accessory for wireless charging using a proprietary electromagnetic induction charging dock, dubbed the "Touchstone Charger." The Touchstone Charger requires a compatible back cover, which was sold separately from the Pre but included in subsequent models.
|
Labor is the muscular contractions to expel the fetus and placenta from where?
|
[
"lungs",
"uterus",
"anus",
"tumors"
] |
B
|
Visit this website (http://openstaxcollege. org/l/embryo_fetus2) to see the stages of human fetal development. Labor is the muscular contractions to expel the fetus and placenta from the uterus. Toward the end of the third trimester, estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin. At this time, the baby reorients, facing forward and down with the back or crown of the head engaging the cervix (uterine opening). This causes the cervix to stretch and nerve impulses are sent to the hypothalamus, which signals the release of oxytocin from the posterior pituitary. Oxytocin causes smooth muscle in the uterine wall to contract. At the same time, the placenta releases prostaglandins into the uterus, increasing the contractions. A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin. As more smooth muscle cells are recruited, the contractions increase in intensity and force. There are three stages to labor. During stage one, the cervix thins and dilates. This is necessary for the baby and placenta to be expelled during birth. The cervix will eventually dilate to about 10 cm. During stage two, the baby is expelled from the uterus. The uterus contracts and the mother pushes as she compresses her abdominal muscles to aid the delivery. The last stage is the passage of the placenta after the baby has been born and the organ has completely disengaged from the uterine wall. If labor should stop before stage two is reached, synthetic oxytocin, known as Pitocin, can be administered to restart and maintain labor.
(e.g. in higher order primates, including humans, and also in rabbits, guinea pigs, mice, and rats)During pregnancy, placentation is the formation and growth of the placenta inside the uterus. It occurs after the implantation of the embryo into the uterine wall and involves the remodeling of blood vessels in order to supply the needed amount of blood. In humans, placentation takes place 7–8 days after fertilization.
Uterine atony is the failure of the uterus to contract adequately following delivery. Contraction of the uterine muscles during labor compresses the blood vessels and slows flow, which helps prevent hemorrhage and facilitates coagulation. Therefore, a lack of uterine muscle contraction can lead to an acute hemorrhage, as the vasculature is not being sufficiently compressed.
This refers to uterine conditions that result in the uterus not having enough coordination or strength to dilate the cervix and push the baby through the birth canal. Issues with uterine contractions are the main cause of prolonged labor during the latent phase. Contractions may not occur as of a result of uterine tumors. In addition, if the uterus is stretched, usually due to previous pregnancies or multiple gestation, contractions may be difficult.
Removal of placental fragments is needed when the placenta cannot be expelled by natural uterine contraction, this can be illustrated with two scenarios that require different treatment methods. In situations where fragments have been separated from the uterus but yet to be expelled, manual extraction will be performed by directly pulling the detached placenta by hand to bring it outside of the body. Whereas in cases where placental fragments are firmly attached to the wall of the uterus, dilation and curettage is the definitive and therapeutic method of choice. Once the remaining placenta is removed, the mother will be able to restore the expected decline in progesterone level and initiate the onset of lactation.
The hormone oxytocin is usually given in the synthetic form of Pitocin. It is administered through an IV throughout the labor process. This hormone stimulates contractions. Pitocin is also used to "restart" labor when it is lagging.The use of misoprostol is also allowed, but close monitoring of the mother is required.
|
What are topographic maps that show water depths called?
|
[
"solenoid maps",
"morainic maps",
"bathymetric maps",
"Water Table maps"
] |
C
|
Topographic maps that show water depths are called bathymetric maps . An example of one is pictured below ( Figure below ). Bathymetric maps are made of any water body, including lakes and oceans. On these maps, the contour lines represent depth below the surface. Therefore, high numbers are deeper depths and low numbers are shallow depths.
Where the water table is below the land surface, its depth reflects the minimum level to which wells must be drilled for groundwater extraction; a spring occurs where it reaches the land surface, and a permanent marsh or lake results where the theoretical water table is above the land surface. The level of the water table is the boundary between the vadose zone and the phreatic zone. Its depth fluctuates seasonally, which accounts for the intermittent flow of bournes.
A topographic map series uses a common specification that includes the range of cartographic symbols employed, as well as a standard geodetic framework that defines the map projection, coordinate system, ellipsoid and geodetic datum. Official topographic maps also adopt a national grid referencing system. Natural Resources Canada provides this description of topographic maps:These maps depict in detail ground relief (landforms and terrain), drainage (lakes and rivers), forest cover, administrative areas, populated areas, transportation routes and facilities (including roads and railways), and other man-made features. Other authors define topographic maps by contrasting them with another type of map; they are distinguished from smaller-scale "chorographic maps" that cover large regions, "planimetric maps" that do not show elevations, and "thematic maps" that focus on specific topics.However, in the vernacular and day to day world, the representation of relief (contours) is popularly held to define the genre, such that even small-scale maps showing relief are commonly (and erroneously, in the technical sense) called "topographic".The study or discipline of topography is a much broader field of study, which takes into account all natural and man-made features of terrain. Maps were among the first artifacts to record observations about topography.
One of the most important applications of the topographic profiles is in the construction of works of great length and small width, for example roads, sewers or pipelines.Sometimes topographical profiles appear in printed maps, such as those designed for navigation routes, excavations and especially for geological maps, where they are used to show the internal structure of the rocks that populate a territory. People who study natural resources such as geologists, geomorphologists, soil scientists and vegetation scholars, among others, build profiles to observe the relationship of natural resources to changes in topography and analyze numerous problems.
The Advanced Topographic Laser Altimeter System (ATLAS) on NASA's Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) is a photon-counting lidar that uses the return time of laser light pulses from the Earth's surface to calculate altitude of the surface. ICESat-2 measurements can be combined with ship-based sonar data to fill in gaps and improve precision of maps of shallow water.Mapping of continental shelf seafloor topography using remotely sensed data has applied a variety of methods to visualise the bottom topography. Early methods included hachure maps, and were generally based on the cartographer's personal interpretation of limited available data.
This is known as the hydrostatic approximation. Hydrostatic models use either pressure or sigma-pressure vertical coordinates. Pressure coordinates intersect topography while sigma coordinates follow the contour of the land.
|
What is the radula made mostly of?
|
[
"casein",
"chlorophyll",
"schist",
"chitin"
] |
D
|
Many species have a feeding structure, the radula , found only in mollusks. The radula can be thought of as a "tongue-like" structure. The radula is made mostly of chitin. Types of radulae range from structures used to scrape algae off of rocks to the beaks of squid and octopuses.
It is made from sorghum repeatedly fermented in stone brick pits. It has large amounts of ester compounds, which impart a layered umami flavor. A highly controversial profile - like it or hate it.
Māori traditional textiles are the indigenous textiles of the Māori people of New Zealand. The organisation Te Roopu Raranga Whatu o Aotearoa, the national Māori weavers' collective, aims to preserve and foster the skills of making and using these materials. Textiles made from locally sourced materials were developed by Māori in New Zealand after migration from Polynesia as the plants used in the Pacific islands did not grow well in the New Zealand climate. In traditional Māori weaving of garments the main fibre is called muka and is made from harakeke.
The taana wild onion Allium polyrrhizum is the main browse eaten by many herd animals, and Mongolians claim that this is essential in producing the proper, hazelnut-like notes of camel airag (fermented milk). The vast desert is crisscrossed by several trade routes, some of which have been in use for thousands of years. Among the most important are those from Kalgan (at the Great Wall) to Ulaanbaatar (960 km (597 mi)); from Jiuquan (in Gansu) to Hami 670 km (416 mi); from Hami to Beijing (2,000 km (1,243 mi)); from Hohhot to Hami and Barkul; and from Lanzhou (in Gansu) to Hami.
The largest amount produced in the laboratory was a cluster of more than 300,000 atoms.Radium (Ra, atomic number 88), is an almost pure-white alkaline earth metal, but it readily oxidizes, reacting with nitrogen (rather than oxygen) on exposure to air, becoming black in color. All isotopes of radium are highly radioactive; the most stable isotope is radium-226, which has a half-life of 1601 years and decays into radon gas. Because of such instability, radium is luminescent, glowing a faint blue.
It is made most often from wheat flour, cooked on a flat or slightly concave iron griddle called a tawa. Traditionally, rotis have also been made from the flour of millet, maize, jowar, bajra, and even rice. Tandoori roti is cooked by sticking the flattened dough to the inside wall of a tandoor oven, where it bakes quickly at a high temperature. Chapatis are made of whole-wheat flour known as atta, mixed into dough with water, edible oil and optional salt in a mixing utensil called a parat, and is cooked on a tava (flat skillet). It is known as phulka in Punjabi and Saraiki, and maani in Sindhi.
|
Energy transferred solely due to a temperature difference is called?
|
[
"chemical energy",
"magnetic energy",
"humidity",
"heat"
] |
D
|
Heat and work are the two distinct methods of energy transfer. Heat is energy transferred solely due to a temperature difference. Any energy unit can be used for heat transfer, and the most common are kilocalorie (kcal) and joule (J). Kilocalorie is defined to be the energy needed to change the temperature of 1.00 kg of water between 14.5ºC and.
They include calorimetry, which is the commonest practical way of finding internal energy differences. The needed temperature can be either empirical or absolute thermodynamic. In contrast, the Carathéodory way recounted just above does not use calorimetry or temperature in its primary definition of quantity of energy transferred as heat.
In thermodynamics, heat is energy transferred to or from a thermodynamic system by mechanisms other than thermodynamic work or transfer of matter, such as conduction, radiation, and friction. Heat refers to a quantity transferred between systems, not to a property of any one system, or "contained" within it. On the other hand, internal energy and enthalpy are properties of a single system. Heat and work depend on the way in which an energy transfer occurred, whereas internal energy is a property of the state of a system and can thus be understood without knowing how the energy got there.
This is known as the gyrator-capacitor model.A widely used analogy in the thermal domain maps temperature difference as the effort variable and thermal power as the flow variable. Again, these are not power conjugate variables, and the ratio, known as thermal resistance, is not really an analogy of either impedance or electrical resistance as far as energy flows are concerned. A compatible analogy could take temperature difference as the effort variable and entropy flow rate as the flow variable.
Even though these motions are called "internal", the external portions of molecules still move—rather like the jiggling of a stationary water balloon. This permits the two-way exchange of kinetic energy between internal motions and translational motions with each molecular collision. Accordingly, as internal energy is removed from molecules, both their kinetic temperature (the kinetic energy of translational motion) and their internal temperature simultaneously diminish in equal proportions.
Fluid, usually water, in the absorber tubes collect the trapped heat and transfer it to a heat storage vault. Heat is transferred either by conduction or convection. When water is heated, kinetic energy is transferred by conduction to water molecules throughout the medium.
|
In which organ does a baby develop?
|
[
"pelvis",
"pancreas",
"ovaries",
"uterus"
] |
D
|
The uterus is a hollow organ with muscular walls. The uterus is where a baby develops until birth. The walls of the uterus stretch to accommodate the growing fetus. The muscles in the walls contract to push the baby out during birth. The uterus is connected to the vagina by a small opening called the cervix.
Gastroschisis develops when the abdominal wall does not completely close, and the organs are present outside of the infant's body. Omphalocele occurs when some of the organs protrude through the muscles of the abdomen in the area surrounding the umbilical cord. Omphalocele can be either minor, with only some of the organs exposed, or severe, with most, if not all of the abdominal organs being exposed.
It is not only mammals that give birth. Some reptiles, amphibians, fish and invertebrates carry their developing young inside them. Some of these are ovoviviparous, with the eggs being hatched inside the mother's body, and others are viviparous, with the embryo developing inside their body, as in the case of mammals.
Three different kidney systems form in the developing embryo: the pronephros, the mesonephros and the metanephros. Only the metanephros develops into the permanent kidney. All three are derived from the intermediate mesoderm.
Both the short gastric arteries and the splenic artery supply it with blood. The germinal centers are supplied by arterioles called penicilliary radicles.In the human until the fifth month of prenatal development, the spleen creates red blood cells; after birth, the bone marrow is solely responsible for hematopoiesis. As a major lymphoid organ and a central player in the reticuloendothelial system, the spleen retains the ability to produce lymphocytes.
It will have divided on its journey to form a blastocyst that will implant itself into the lining of the uterus – the endometrium, where it will receive nutrients and develop into the embryo proper and later fetus for the duration of the pregnancy. In the human embryo, the uterus develops from the paramesonephric ducts which fuse into the single organ known as a simplex uterus.
|
What part of an experiment or other investigation consists of the individuals or events that are studied?
|
[
"hypothesis",
"sample",
"experimental control",
"independent variable"
] |
B
|
The sample in an experiment or other investigation consists of the individuals or events that are studied. Typically, the sample is much smaller than all such individuals or events that exist in the world. Whether the results based on the sample are true in general cannot be known for certain. However, the larger the sample is, the more likely it is that the results are generally true. Similarly, the more times that an experiment is repeated and the same results obtained, the more likely the results are valid. This is why scientific experiments should always be repeated.
Experimental archaeology (also called experiment archaeology) is a field of study which attempts to generate and test archaeological hypotheses, usually by replicating or approximating the feasibility of ancient cultures performing various tasks or feats. It employs a number of methods, techniques, analyses, and approaches, based upon archaeological source material such as ancient structures or artifacts.It is distinct from uses of primitive technology without any concern for archaeological or historical study. Living history and historical reenactment, which are generally undertaken as hobbies, are non-archaeological counterparts of this academic discipline. One of the main forms of experimental archaeology is the creation of copies of historical structures using only historically accurate technologies.
Scientific instruments were developed to aid human abilities of observation, such as weighing scales, clocks, telescopes, microscopes, thermometers, cameras, and tape recorders, and also translate into perceptible form events that are unobservable by the senses, such as indicator dyes, voltmeters, spectrometers, infrared cameras, oscilloscopes, interferometers, Geiger counters, and radio receivers. One problem encountered throughout scientific fields is that the observation may affect the process being observed, resulting in a different outcome than if the process was unobserved. This is called the observer effect.
They are considered "event based" studies because time measurements are triggered by the occurrence of predetermined events. Work sampling is a method in which the job is sampled at random intervals to determine the proportion of total time spent on a particular task. It provides insight into how often workers are performing tasks which might cause strain on their bodies.
The Experiment search record refers to one or more experiments with a set of scientific aims. Here a user is able to retrieve full data source information. This information includes the institution of the submitter, links to the original data submissions in GEO and SRA, links to literature citations in PubMed and/or full text articles in Pubmed. Experiment records contain a unique accession number that includes a prefix 'ESS'.
Thus, in an attempt to productively participate, the subject may try to gain knowledge of the hypothesis being tested in the experiment and alter their behavior in an attempt to support that hypothesis. Orne conceptualized this change by saying that the experiment may appear to a participant as a problem, and it is his or her job to find the solution to that problem, which would be behaving in a way that would lend support to the experimenter's hypothesis. Alternatively, a participant may try to discover the hypothesis simply to provide faulty information and wreck the hypothesis.
|
The intentional release or spread of agents of disease is known as what?
|
[
"act of war",
"bioterrorism",
"pandemic",
"disaster"
] |
B
|
Bioterrorism is the intentional release or spread of agents of disease. The agents may be viruses, bacteria, or toxins produced by bacteria. The agents may spread through the air, food, or water; or they may come into direct contact with the skin. Two of the best known bioterrorism incidents in the U. S. occurred early in this century:.
It can be spread within a hospital. The virulent and toxigenic strains produce an exotoxin formed by two polypeptide chains, which is itself produced when a bacterium is transformed by a gene from the β prophage.Several species cause disease in animals, most notably C. pseudotuberculosis, which causes the disease caseous lymphadenitis, and some are also pathogenic in humans. Some attack healthy hosts, while others tend to attack the immunocompromised.
Airborne An airborne disease is any disease that is caused by pathogens and transmitted through the air. Foodborne Foodborne illness or food poisoning is any illness resulting from the consumption of food contaminated with pathogenic bacteria, toxins, viruses, prions or parasites. Infectious Infectious diseases, also known as transmissible diseases or communicable diseases, comprise clinically evident illness (i.e., characteristic medical signs or symptoms of disease) resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism. Included in this category are contagious diseases – an infection, such as influenza or the common cold, that commonly spreads from one person to another – and communicable diseases – a disease that can spread from one person to another, but does not necessarily spread through everyday contact.
Asymptomatic carriers can be categorized by their current disease state. When an individual transmits pathogens immediately following infection but prior to developing symptoms, they are known as an incubatory carrier. Humans are also capable of spreading disease following a period of illness. Typically thinking themselves cured of the disease, these individuals are known as convalescent carriers.
As medicine became a science, the descriptions of disease became less vague. Although medicine could do little at the time to alleviate the suffering of those infected, measures to control the spread of diseases were used.
The Diseases of Animals Act is a series of acts of Parliament of the UK to deal with the possibility of the accrual of economic harm or intra-species contamination. It follows on from the 19th-century series notation Contagious Diseases (Animals) Act. The Act of 1884 was designed to combat "heavy losses" due to cattle diseases such as rinderpest, contagious bovine pleuropneumonia and foot-and-mouth disease (FMD).
|
If pressure is exerted on the rock from one direction, the rock forms layers. this is called what?
|
[
"protonation",
"stratification",
"foliation",
"sedimentation"
] |
C
|
During metamorphism, a rock may change chemically. Ions move in or out of a mineral. This creates a different mineral. The new minerals that form during metamorphism are more stable in the new environment. Extreme pressure may lead to physical changes. If pressure is exerted on the rock from one direction, the rock forms layers. This is foliation . If pressure is exerted from all directions, the rock usually does not show foliation.
This is called a shear band. The pore network is rearranged by granular movements (also called particulate flow), hence moderately enhance permeability. However, continuing deformation leads to the cataclasis of mineral grains which will further reduce permeability later on (section 3.2.3) (Figure 4).
In geology, shear is the response of a rock to deformation usually by compressive stress and forms particular textures. Shear can be homogeneous or non-homogeneous, and may be pure shear or simple shear. Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics. The process of shearing occurs within brittle, brittle-ductile, and ductile rocks. Within purely brittle rocks, compressive stress results in fracturing and simple faulting.
Fracturing rocks at great depth frequently become suppressed by pressure due to the weight of the overlying rock strata and the cementation of the formation. This suppression process is particularly significant in "tensile" (Mode 1) fractures which require the walls of the fracture to move against this pressure. Fracturing occurs when effective stress is overcome by the pressure of fluids within the rock.
See Egyptian. drag Also rope drag. Friction from the rope running over the rock and through the lower protection.
Although the transition zone generally marks a shift from brittle rock to ductile rock, exceptions exist in certain conditions. If stress is applied rapidly, rock below the transition zone may fracture. Above the transition zone, the rock may deform ductilely if pore fluids are present and stress is applied gradually.
|
What term is used to describe the average weather of a place over many years?
|
[
"atmosphere",
"landscape",
"climate",
"meteorology"
] |
C
|
Climate is the average weather of a place over many years. It includes average temperatures. It also includes average precipitation. The timing of precipitation is part of climate as well. What determines the climate of a place? Latitude is the main factor. A nearby ocean or mountain range can also play a role.
Climate is the statistics (usually, mean or variability) of weather: the classical period for averaging weather variables is 30 years in accordance with the definition set by the World Meteorological Organization.Instrumental temperature records have shown a robust multi-decadal long-term trend of global warming since the end of the 19th century, reversing longer term cooling in previous centuries as seen in paleoclimate records. There has been considerable variability at shorter interannual to decadal periods, with hiatus periods showing less certain short-term trends. The 1998–2012 hiatus shows a rise of 0.05 °C per decade, compared with a longer term rise of 0.12 °C per decade over the period from 1951 to 2012. The appearance of hiatus is sensitive to the start and end years chosen: a 15-year period starting in 1996 shows a rate of increase of 0.14 °C per decade, but taking 15 years from 1997 the rate reduces to 0.07 °C per decade.
clear-air turbulence climate The statistics of weather in a given region over long periods of time, measured by assessing long-term patterns of variation in temperature, atmospheric pressure, humidity, wind, precipitation, and other meteorological variables. The climate of a particular location is generated by the interactions of the atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere and strongly influenced by latitude, altitude, and local topography. Climates are often classified according to the averages or typical ranges of different variables, most commonly temperature and precipitation.
The following is a list of cities by sunshine duration. Sunshine duration is a climatological indicator, measuring duration of sunshine in given period (usually, a day or a year) for a given location on Earth, typically expressed as an averaged value over several years. It is a general indicator of cloudiness of a location, and thus differs from insolation, which measures the total energy delivered by sunlight over a given period. Sunshine duration is usually expressed in hours per year, or in (average) hours per day. The first measure indicates the general sunniness of a location compared with other places, while the latter allows for comparison of sunshine in various seasons in the same location. Another often-used measure is percentage ratio of recorded bright sunshine duration and daylight duration in the observed period.
Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the time varying conditions within the Solar System, including the solar wind, emphasizing the space surrounding the Earth, including conditions in the magnetosphere, ionosphere, thermosphere, and exosphere. Space weather is distinct from, but conceptually related to, the terrestrial weather of the atmosphere of Earth (troposphere and stratosphere). The term "space weather" was first used in the 1950s and came into common usage in the 1990s. Later, it was generalized to a "space climate" research discipline, which focuses on general behaviors of longer and larger-scale variabilities and effects.
For example, in Mexico it is known as "storm season". Different names are given to the various short "seasons" of the year by the First Nations of Northern Australia: the wet season typically experienced there from December to March is called Gudjewg. The precise meaning of the word is disputed, although it is widely accepted to relate to the severe thunderstorms, flooding, and abundant vegetation growth commonly experienced at this time.
|
A long chain of monosaccharides linked by glycosidic bonds is known as what?
|
[
"sulfate",
"polysaccharide",
"Fructose",
"polymers"
] |
B
|
Polysaccharides A long chain of monosaccharides linked by glycosidic bonds is known as a polysaccharide (poly- = “many”). The chain may be branched or unbranched, and it may contain different types of monosaccharides. The molecular weight may be 100,000 daltons or more depending on the number of monomers joined. Starch, glycogen, cellulose, and chitin are primary examples of polysaccharides. Starch is the stored form of sugars in plants and is made up of a mixture of amylose and amylopectin (both polymers of glucose). Plants are able to synthesize glucose, and the excess glucose, beyond the plant’s immediate energy needs, is stored as starch in different plant parts, including roots and seeds. The starch in the seeds provides food for the embryo as it germinates and can also act as a source of food for humans and animals. The starch that is consumed by humans is broken down by enzymes, such as salivary amylases, into smaller molecules, such as maltose and glucose. The cells can then absorb the glucose. Starch is made up of glucose monomers that are joined by α 1-4 or α 1-6 glycosidic bonds. The numbers 1-4 and 1-6 refer to the carbon number of the two residues that have joined to form the bond. As illustrated in Figure 3.9, amylose is starch formed by unbranched chains of glucose monomers (only α 1-4 linkages), whereas amylopectin is a branched polysaccharide (α 1-6 linkages at the branch points).
Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Some, such as the raffinose series, occur as storage or transport carbohydrates in plants. Others, such as maltodextrins or cellodextrins, result from the microbial breakdown of larger polysaccharides such as starch or cellulose.
However, some biological substances commonly called "monosaccharides" do not conform to this formula (e.g. uronic acids and deoxy-sugars such as fucose) and there are many chemicals that do conform to this formula but are not considered to be monosaccharides (e.g. formaldehyde CH2O and inositol (CH2O)6).The open-chain form of a monosaccharide often coexists with a closed ring form where the aldehyde/ketone carbonyl group carbon (C=O) and hydroxyl group (–OH) react forming a hemiacetal with a new C–O–C bridge. Monosaccharides can be linked together into what are called polysaccharides (or oligosaccharides) in a large variety of ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is a modified version of ribose; chitin is composed of repeating units of N-acetyl glucosamine, a nitrogen-containing form of glucose.
Structurally, they are glycosides, which are sugars bonded to one or more organic molecules. In a glycoside molecule, the sugar is the glycone part, while one or more non-sugar organic molecules form the aglycone part.
Galactosides play significant roles in metabolic processes of many organisms and are hydrolyzed by a class of enzymes called galactosidases and are classified according to what type of glycosidic linkage on the galactoside they will break. For example, enzymes that hydrolyze the β-galactoside glycosidic bond are called β-galactosidases, while those that hydrolyze the α-galactoside glycosidic bond are known as α-galactosidases. == References ==
Oligosaccharides may be sequenced using tandem mass spectrometry in a similar manner to peptide sequencing. Fragmentation generally occurs on either side of the glycosidic bond (b, c, y and z ions) but also under more energetic conditions through the sugar ring structure in a cross-ring cleavage (x ions). Again trailing subscripts are used to indicate position of the cleavage along the chain. For cross ring cleavage ions the nature of the cross ring cleavage is indicated by preceding superscripts.
|
How do genes located on separate nonhomologous chromosomes sort?
|
[
"mechanically",
"intradependently",
"typically",
"independently"
] |
D
|
Linked Genes Violate the Law of Independent Assortment Although all of Mendel’s pea characteristics behaved according to the law of independent assortment, we now know that some allele combinations are not inherited independently of each other. Genes that are located on separate nonhomologous chromosomes will always sort independently. However, each chromosome contains hundreds or thousands of genes, organized linearly on chromosomes like beads on a string. The segregation of alleles into gametes can be influenced by linkage, in which genes that are located physically close to each other on the same chromosome are more likely to be inherited as a pair. However, because of the process of recombination, or “crossover,” it is possible for two genes on the same chromosome to behave independently, or as if they are not linked. To understand this, let’s consider the biological basis of gene linkage and recombination. Homologous chromosomes possess the same genes in the same linear order. The alleles may differ on homologous chromosome pairs, but the genes to which they correspond do not. In preparation for the first division of meiosis, homologous chromosomes replicate and synapse. Like genes on the homologs align with each other. At this stage, segments of homologous chromosomes exchange linear segments of genetic material (Figure 12.18). This process is called recombination, or crossover, and it is a common genetic process. Because the genes are aligned during recombination, the gene order is not altered. Instead, the result of recombination is that maternal and paternal alleles are combined onto the same chromosome. Across a given chromosome, several recombination events may occur, causing extensive shuffling of alleles.
In a sense, gene arrangements are visible in the banding patterns of each chromosome. Chromosome rearrangements, especially inversions, make it possible to see which species are closely related. The results are clear.
: 20 During the process of meiotic cell division, an event called genetic recombination or crossing-over can sometimes occur, in which a length of DNA on one chromatid is swapped with a length of DNA on the corresponding homologous non-sister chromatid. This can result in reassortment of otherwise linked alleles. : 5.5 The Mendelian principle of independent assortment asserts that each of a parent's two genes for each trait will sort independently into gametes; which allele an organism inherits for one trait is unrelated to which allele it inherits for another trait.
Whereas genes located on different chromosomes assort independently and have a recombination frequency of 50%, linked genes have a recombination frequency that is less than 50%. As an example of linkage, consider the classic experiment by William Bateson and Reginald Punnett.
Each gene maps to the same chromosome in every cell. Linkage is determined by the presence of two or more loci on the same chromosome. The entire chromosomal set of a species is known as a karyotype. A seemingly logical consequence of descent from common ancestors is that more closely related species should have more chromosomes in common. However, it is now widely thought that species may have phenetically similar karyotypes due to genomic conservation. Therefore, in comparative cytogenetics, phylogenetic relationships should be determined on the basis of the polarity of chromosomal differences (derived traits).
Therefore, genes don't have to be in close proximity to be co-expressed. Therefore, it was long assumed that eukaryotic genes were randomly distributed across the genome due to the high rate of chromosome rearrangements. But because the complete sequence of genomes became available it became possible to absolutely locate a gene and measure its distance to other genes.
|
What type of mass movement is a sudden movement of large blocks of rock and soil down a slope?
|
[
"deluge",
"resurgence",
"downturn",
"slump"
] |
D
|
Two other types of mass movement are slump and creep. They usually aren’t as destructive as landslides and mudslides. Slump is the sudden movement of large blocks of rock and soil down a slope. Creep is the very slow movement of rock and soil down a slope. It causes trees, fence posts, and other structures to tilt downhill.
Whilst the example given in Figures A and B is clearly an artificial situation, the mechanics are essentially as per a real landslide. In some situations, the presence of high levels of fluid may destabilise the slope through other mechanisms, such as: Fluidization of debris from earlier events to form debris flows; Loss of suction forces in silty materials, leading to generally shallow failures (this may be an important mechanism in residual soils in tropical areas following deforestation); Undercutting of the toe of the slope through river erosion. Destabilizing of non-lithified earth materials through soil-piping.Considerable efforts have been made to understand the triggers for landsliding in natural systems, with quite variable results.
These processes are complex, but can be sufficient to induce failure of the slope. These processes can be much more serious in mountainous areas in which the seismic waves interact with the terrain to produce increases in the magnitude of the ground accelerations. This process is termed 'topographic amplification'. The maximum acceleration is usually seen at the crest of the slope or along the ridge line, meaning that it is a characteristic of seismically triggered landslides that they extend to the top of the slope.
: Ch 2.10 Clays may initially support a steep slope when excavated, but are subject to creep and sudden large-scale collapse when subjected to shock loads or vibration. : Ch 2.11 Unconsolidated sand – seasonal shifts. : Ch 2.13 Underwater sand dunes can form where there are strong currents, which may move with the currents, as sand is lifted by flow over the back of the dune, and dropped at the front. This can be a problem when laying pipelines, and may require deeper than usual burial. : Ch 2.14
An earthflow (earth flow) is a downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravity. It is an intermediate type of mass wasting that is between downhill creep and mudflow. The types of materials that are susceptible to earthflows are clay, fine sand and silt, and fine-grained pyroclastic material.When the ground materials become saturated with enough water, they will start flowing (soil liquefaction). Its speed can range from being barely noticeable to rapid movement. The velocity of the flow is dictated by water content: the higher the water content is, the higher the velocity will be. Because of the dependency on water content for the velocity of the flow, it can take minutes or years for the materials to move down the slope.
4. The collection of fine, granular material that is moved down a slope by erosional processes. See also wash slope.
|
What consists of structures that produce eggs and secrete female sex hormones?
|
[
"male reproductive system",
"female neural system",
"asexual reproductive system",
"female reproductive system"
] |
D
|
The female reproductive system consists of structures that produce eggs and secrete female sex hormones. They also provide a site for fertilization and enable the development and birth of a fetus. They include the vagina, uterus, ovaries, and fallopian tubes.
In both males and females, the sex organs consist of three structures: the gonads, the internal genitalia, and the external genitalia. In males, the gonads are the testes and in females they are the ovaries. These are the organs that produce gametes (egg and sperm), the reproductive cells that will eventually meet to form the fertilized egg (zygote).
The female portion contains the oviduct, transferring eggs from the common duct to the atrium. The atrium is further subdivided into an upper and lower atrium. A stimulating organ (ligula) can also be found in the atrium.
Through an interplay of hormones that includes follicle stimulating hormone that stimulates folliculogenesis and oogenesis creates a mature egg cell, the female gamete. Fertilization is the event where the egg cell fuses with the male gamete, spermatozoon. After the point of fertilization, the fused product of the female and male gamete is referred to as a zygote or fertilized egg. The fusion of female and male gametes usually occurs following the act of sexual intercourse.
The ovaries produce the ova (egg cells). The external sex organs are also known as the genitals and these are the organs of the vulva including the labia, clitoris, and vaginal opening. The vagina is connected to the uterus at the cervix.
In most species the genitalia are flanked by two soft lobes, although they may be specialized and sclerotized in some species for ovipositing in area such as crevices and inside plant tissue. Hormones and the glands that produce them run the development of butterflies and moths as they go through their life cycle, called the endocrine system. The first insect hormone PTTH (Prothoracicotropic hormone) operates the species life cycle and diapause (see the relates section).
|
Lactic acid fermentation is common in muscle cells that have run out of what?
|
[
"carbon",
"helium",
"oxygen",
"nitrogen"
] |
C
|
Figure 7.14 Lactic acid fermentation is common in muscle cells that have run out of oxygen.
The by-product of anaerobic glycolysis—lactate—has traditionally been thought to be detrimental to muscle function. However, this appears likely only when lactate levels are very high. Elevated lactate levels are only one of many changes that occur within and around muscle cells during intense exercise that can lead to fatigue.
Prior to the formation of the lactate shuttle hypothesis, lactate had long been considered a byproduct resulting from glucose breakdown through glycolysis in times of anaerobic metabolism. As a means of regenerating oxidized NAD+, lactate dehydrogenase catalyzes the conversion of pyruvate to lactate in the cytosol, oxidizing NADH to NAD+, regenerating the necessary substrate needed to continue glycolysis. Lactate is then transported from the peripheral tissues to the liver by means of the Cori Cycle where it is reformed into pyruvate through the reverse reaction using lactate dehydrogenase. By this logic, lactate was traditionally considered a toxic metabolic byproduct that could give rise to fatigue and muscle pain during times of anaerobic respiration. Lactate was essentially payment for ‘oxygen debt’ defined by Hill and Lupton as the ‘total amount of oxygen used, after cessation of exercise in recovery therefrom’.
Brewers of more common beer styles would ensure that no such bacteria are allowed to enter the fermenter. Other sour styles of beer include Berliner weisse, Flanders red and American wild ale.In winemaking, a bacterial process, natural or controlled, is often used to convert the naturally present malic acid to lactic acid, to reduce the sharpness and for other flavor-related reasons. This malolactic fermentation is undertaken by lactic acid bacteria. While not normally found in significant quantities in fruit, lactic acid is the primary organic acid in akebia fruit, making up 2.12% of the juice.
It is important to understand the difference between lactate threshold and lactic acid tolerance. Aerobic training will not help with lactic acid tolerance, however, it will increase the lactate threshold. The body will build a better tolerance of the effects of lactic acid over time by doing anaerobic training, allowing the muscles’ ability to work in the presence of increased lactic acid. Training at or slightly above the lactate threshold improves the lactic acid tolerance.
The presence of free fatty acids increases the level of phosphorylation, thereby decreasing PDH activity. During exercise, however, these effects are overruled, and there is a much higher level of dephosphorylated PDHA1 in the cells. In certain muscles, such as the triceps, the metabolic enzyme profile seems to directly affect the level of PDH activity, which can result in higher levels of lactate in muscles with these characteristics.
|
How many sets of chromosomes does each somatic cell have?
|
[
"one",
"four",
"six",
"two"
] |
D
|
Each human somatic cell (a body cell, or every cell other than a gamete) normally has two sets of chromosomes, one set inherited from each parent. These cells are said to have a diploid number of chromosomes. Each set contains 23 chromosomes, for a total of 46 chromosomes. Each chromosome differs in size, from about 250 million nucleotide pairs on the largest chromosome (chromosome #1) to less than 50 million nucleotide pairs on chromosome #22. Each chromosome contains a specific set of genes, as well as regulatory elements and other nucleotide sequences, making each chromosome essential to survival.
For example, most animals are diploid and produce haploid gametes. During meiosis, sex cell precursors have their number of chromosomes halved by randomly "choosing" one member of each pair of chromosomes, resulting in haploid gametes.
A pronucleus (PL: pronuclei) denotes the nucleus found in either a sperm or egg cell during the process of fertilization. The sperm cell undergoes a transformation into a pronucleus after entering the egg cell but prior to the fusion of the genetic material of both the sperm and egg. In contrast, the egg cell possesses a pronucleus once it becomes haploid, not upon the arrival of the sperm cell. Haploid cells, such as sperm and egg cells in humans, carry half the number of chromosomes present in somatic cells, with 23 chromosomes compared to the 46 found in somatic cells.
According to the principle of nuclear equivalence, the nuclei of essentially all differentiated adult cells of an individual are genetically (though not necessarily metabolically) identical to one another and to the nucleus of the zygote from which they descended. This means that virtually all somatic cells in an adult have the same genes. However, different cells express different subsets of these genes.
Most animals and some plants have paired chromosomes, and are described as diploid. They have two versions of each chromosome, one contributed by the mother's ovum, and the other by the father's sperm, known as gametes, described as haploid, and created through meiosis. These gametes then fuse during fertilization during sexual reproduction, into a new single cell zygote, which divides multiple times, resulting in a new organism with the same number of pairs of chromosomes in each (non-gamete) cell as its parents. In mammalian genetics, autosomal dominant disorders have pedigrees that demonstrate a vertical pattern of inheritance.
Normally humans have 2 copies of chromosome 16, one inherited by each parent. This chromosome represents almost 3% of all DNA in cells.
|
Nonflowering vascular plants have three basic types of leaves: microphylls, fronds, and what other type?
|
[
"molds",
"tubes",
"stems",
"needles"
] |
D
|
Leaves may vary in size, shape, and their arrangement on stems. Nonflowering vascular plants have three basic types of leaves: microphylls (“tiny leaves”), fronds, and needles. Figure below describes each type.
Non-vascular plants are often among the first species to move into new and inhospitable territories, along with prokaryotes and protists, and thus function as pioneer species. Non-vascular plants do not have a wide variety of specialized tissue types. Mosses and leafy liverworts have structures called phyllids that resemble leaves, but only consist of single sheets of cells with no internal air spaces, no cuticle or stomata, and no xylem or phloem.
A major difference between vascular and non-vascular plants is that in the latter the haploid gametophyte is the more visible and longer-lived stage. In vascular plants, the diploid sporophyte has evolved as the dominant and visible phase of the life cycle. In seed plants and some other groups of vascular plants the gametophyte phases are strongly reduced in size and contained within the pollen and ovules. The female gametophyte is entirely contained within the sporophyte's tissues, while the male gametophyte in its pollen grain is released and transferred by wind or animal vectors to fertilize the ovules.
Some members of both of the two modern classes of Lycopodiophyta (Lycopodiopsida and Isoetopsida) produce strobili. In all cases, the lateral organs of the strobilus are microphylls, bearing sporangia. In other lycophytes, ordinary foliage leaves can act as sporophylls, and there are no organized strobili.
The leaves may have prominent or more or less obscured parallel veins, and the leaf surfaces may be hairless, or carry long soft or coarse hairs. The texture of the leaves may be cartilaginous, leathery or herbaceous. The flowers are at the end of one or several branching inflorescence stalks, that carry several bracts much smaller than the leaves, at least subtending each of the branches.
The extant lycophytes are vascular plants (tracheophytes) with microphyllous leaves, distinguishing them from the euphyllophytes (plants with megaphyllous leaves). The sister group of the extant lycophytes and their closest extinct relatives are generally believed to be the zosterophylls, a paraphyletic or plesion group. Ignoring some smaller extinct taxa, the evolutionary relationships are as shown below. As of 2019, there was broad agreement, supported by both molecular and morphological evidence, that the extant lycophytes fell into three groups, treated as orders in PPG I, and that these, both together and individually, are monophyletic, being related as shown in the cladogram below:
|
What is the most common plant-like protist?
|
[
"mundane algae",
"invasive algae",
"unicellular algae",
"esoteric algae"
] |
C
|
Ginkgoes, like cycads, has separate female and male plants. The male trees are usually preferred for landscaping because the seeds produced by the female plants smell terrible when they ripen.
They are mostly single-celled and microscopic. The term protist came into use historically as a term of convenience for eukaryotes that cannot be strictly classified as plants, animals or fungi. They are not a part of modern cladistics because they are paraphyletic (lacking a common ancestor for all descendants).
Acanthocorbis, Amoenoscopa, Apheloecion, Bicosta, Calliacantha, Calotheca, Campanoeca, Campyloacantha, Conion, Cosmoeca, Crinolina, Crucispina, Diaphanoeca, Didymoeca, Kakoeca, Monocosta, Nannoeca, Parvicorbicula, Platypleura, Pleurasiga, Polyfibula, Saepicula, Saroeca, Spinoeca, Spiraloecion, Stephanacantha, Stephanoeca, Syndetophyllum. Metazoa Haeckel 1874, emend. Adl et al. 2005 . Excluded from protists.
Protists can be broadly divided into four groups depending on whether their nutrition is plant-like, animal-like, fungal-like, or a mixture of these. Protists are highly diverse organisms currently organised into 18 phyla, but are not easy to classify. Studies have shown high protist diversity exists in oceans, deep sea-vents and river sediments, suggesting a large number of eukaryotic microbial communities have yet to be discovered.
There has been little research on mixotrophic protists, but recent studies in marine environments found mixotrophic protests contribute a significant part of the protist biomass. Since protists are eukaryotes they possess within their cell at least one nucleus, as well as organelles such as mitochondria and Golgi bodies. Protists are asexual but can reproduce rapidly through mitosis or by fragmentation.
Others class any unicellular eukaryotic microorganism as Protists, and make no reference to 'Protozoa'. In 2005, members of the Society of Protozoologists voted to change its name to the International Society of Protistologists.By 1954, Protozoa were classified as "unicellular animals", as distinct from the "Protophyta", single-celled photosynthetic algae, which were considered primitive plants. In the system of classification published in 1964 by B. M. Honigsberg and colleagues, the phylum Protozoa was divided according to the means of locomotion, such as by cilia or flagella.In the system of eukaryote classification published by the International Society of Protistologists in 2012, members of the old phylum Protozoa have been distributed among a variety of supergroups.
|
What biochemicals mediate changes in target cells by binding to specific receptors?
|
[
"amino acids",
"acids",
"enzymes",
"hormones"
] |
D
|
37.2 | How Hormones Work By the end of this section, you will be able to: • Explain how hormones work • Discuss the role of different types of hormone receptors Hormones mediate changes in target cells by binding to specific hormone receptors. In this way, even though hormones circulate throughout the body and come into contact with many different cell types, they only affect cells that possess the necessary receptors. Receptors for a specific hormone may be found on many different cells or may be limited to a small number of specialized cells. For example, thyroid hormones act on many different tissue types, stimulating metabolic activity throughout the body. Cells can have many receptors for the same hormone but often also possess receptors for different types of hormones. The number of receptors that respond to a hormone determines the cell’s sensitivity to that hormone, and the resulting cellular response. Additionally, the number of receptors that respond to a hormone can change over time, resulting in increased or decreased cell sensitivity. In up-regulation, the number of receptors increases in response to rising hormone levels, making the cell more sensitive to the hormone and allowing for more cellular activity. When the number of receptors decreases in response to rising hormone levels, called down-regulation, cellular activity is reduced. Receptor binding alters cellular activity and results in an increase or decrease in normal body processes. Depending on the location of the protein receptor on the target cell and the chemical structure of the hormone, hormones can mediate changes directly by binding to intracellular hormone receptors and modulating gene transcription, or indirectly by binding to cell surface receptors and stimulating signaling pathways.
Two models have been proposed to explain transmembrane receptors' mechanism of action. Dimerization: The dimerization model suggests that prior to ligand binding, receptors exist in a monomeric form. When agonist binding occurs, the monomers combine to form an active dimer. Rotation: Ligand binding to the extracellular part of the receptor induces a rotation (conformational change) of part of the receptor's transmembrane helices. The rotation alters which parts of the receptor are exposed on the intracellular side of the membrane, altering how the receptor can interact with other proteins within the cell.
Steroid hormone receptors and related receptors are generally soluble proteins that function through gene activation. Lipid-soluble hormones target specific sequences of DNA by diffusing into the cell. When they have diffused into the cell, they bind to receptors (intracellular), and migrate into the nucleus. Their response elements are DNA sequences (promoters) that are bound by the complex of the steroid bound to its receptor.
Historically, cellular receptors have been thought to be activated when bound to their ligand, and are relatively inactive when no ligand is present. A number of receptors have been found that do not fit into this conceptual mould, and DCC is one of them. These receptors are active both with ligand bound and unbound, but the signals transmitted are different when the receptors are ligand bound.
The targeting ligand attached to the liposome attaches to the binding site found on the cell of interest. The particles are transported to lysosomes to be processed. This process allows the molecules to cross the blood-brain barrier, which allows the drug to be delivered to tissue that is relatively difficult to reach without a specific mechanism.
In cellular biology, dependence receptors are proteins that mediate programmed cell death by monitoring the absence of certain trophic factors (or, equivalently, the presence of anti-trophic factors) that otherwise serve as ligands (interactors) for the dependence receptors. A trophic ligand is a molecule whose protein binding stimulates cell growth, differentiation, and/or survival. Cells depend for their survival on stimulation that is mediated by various receptors and sensors, and integrated via signaling within the cell and between cells.
|
New land can be created when what happens to a volcano?
|
[
"it evolves",
"it dies",
"it erupts",
"it stays dormant"
] |
C
|
New land can be created by volcanic eruptions.
As the overlying tectonic plate moves over this hotspot, the eruption of magma from the fixed plume onto the surface is expected to form a chain of volcanoes that parallels plate motion. The Hawaiian Islands chain in the Pacific Ocean is the archetypal example. It has recently been discovered that the volcanic locus of this chain has not been fixed over time, and it thus joined the club of the many type examples that do not exhibit the key characteristic originally proposed.The eruption of continental flood basalts is often associated with continental rifting and breakup. This has led to the hypothesis that mantle plumes contribute to continental rifting and the formation of ocean basins.
A polygenetic volcanic field is a group of polygenetic volcanoes, each of which erupts repeatedly, in contrast with monogenetic volcanoes, each of which erupts only once. Polygenetic volcanic fields generally occur where there is a high-level magma chamber. These volcanic fields may show lithological discontinuities due to major changes in magma chemistry, volcanotectonic events, or long erosional intervals, and may last over 10 million years. Unlike monogenetic volcanoes, polygenetic volcanoes reach massive sizes, such as Mauna Loa, which is the world's largest active volcano. Polygenetic volcanoes include stratovolcanoes, complex volcanoes, somma volcanoes, shield volcanoes and calderas.
The crust, having already reached its failure point, just stayed in place and younger volcanoes formed. Tharsis volcanism involved very low viscosity magma, forming shield volcanoes similar to those of the Hawaiian Island chain, but, because there is minor or no current active plate tectonics on Mars, the hotspot activity led to very long histories of repeated volcanic eruptions at the same spots, creating some of the largest volcanoes in the solar system, including the biggest, Olympus Mons.Landslides have left numerous deposits on the floor of Valles Marineris and contributed to widening it. Possible triggers of landslides are quakes caused by tectonic activity or impact events.
Consequently, the closing of the fractures in the roof rocks by precipitation of minerals allow confining pressure to increase once again. As time passed, increasingly felsic magmas rise up into the core of the volcano. Some of these later magmas probably erupt on the surface, forming new layers of volcanic rocks that will later be removed by erosion.Finally, volcanic activity ceased and erosion removed the upper portions of the volcano and exposed the intrusive rocks and stockwork mineralization that used to lie within.
In recorded history, explosive eruptions at subduction zone (convergent-boundary) volcanoes have posed the greatest hazard to civilizations. Subduction-zone stratovolcanoes, such as Mount St. Helens, Mount Etna and Mount Pinatubo, typically erupt with explosive force because the magma is too viscous to allow easy escape of volcanic gases. As a consequence, the tremendous internal pressures of the trapped volcanic gases remain and intermingle in the pasty magma.
|
To calculate acceleration without a change in direction, you just divide the change in velocity by the change in what?
|
[
"weight",
"height",
"size",
"time"
] |
D
|
Calculating acceleration is complicated if both speed and direction are changing. It’s easier to calculate acceleration when only speed is changing. To calculate acceleration without a change in direction, you just divide the change in velocity (represented by ) by the change in time (represented by ). The formula for acceleration in this case is:.
The velocity vector can change in magnitude and in direction or both at once. Hence, the acceleration accounts for both the rate of change of the magnitude of the velocity vector and the rate of change of direction of that vector. The same reasoning used with respect to the position of a particle to define velocity, can be applied to the velocity to define acceleration. The acceleration of a particle is the vector defined by the rate of change of the velocity vector.
For constant velocity the position at time t will be where x0 is the position at time t = 0. Velocity is the time derivative of position. Its dimensions are length/time. Acceleration a of a point is vector which is the time derivative of velocity. Its dimensions are length/time2.
For classical (Galileo-Newtonian) mechanics, the transformation law from one inertial or accelerating (including rotation) frame (reference frame traveling at constant velocity - including zero) to another is the Galilean transform. Unprimed quantities refer to position, velocity and acceleration in one frame F; primed quantities refer to position, velocity and acceleration in another frame F' moving at translational velocity V or angular velocity Ω relative to F. Conversely F moves at velocity (—V or —Ω) relative to F'. The situation is similar for relative accelerations.
Delta-v is typically provided by the thrust of a rocket engine, but can be created by other engines. The time-rate of change of delta-v is the magnitude of the acceleration caused by the engines, i.e., the thrust per total vehicle mass. The actual acceleration vector would be found by adding thrust per mass on to the gravity vector and the vectors representing any other forces acting on the object. The total delta-v needed is a good starting point for early design decisions since consideration of the added complexities are deferred to later times in the design process.
The velocity of a particle is a vector quantity that describes the direction as well as the magnitude of motion of the particle. More mathematically, the rate of change of the position vector of a point with respect to time is the velocity of the point. Consider the ratio formed by dividing the difference of two positions of a particle by the time interval. This ratio is called the average velocity over that time interval and is defined as where Δ r {\displaystyle \Delta \mathbf {r} } is the change in the position vector during the time interval Δ t {\displaystyle \Delta t} .
|
What is reduced and forms part of the gelatinous disks sandwiched between the vertebrae in humans?
|
[
"the clavicle",
"the sacrum",
"the notochord",
"the pelvis"
] |
C
|
Intervertebral spinal discs consist of an outer anulus fibrosus and an inner nucleus pulposus. The anulus fibrosus forms a rigid ring around the nucleus pulposus early in human development, and the gelatinous contents of the nucleus pulposus are thus contained within the disc. Discs separate the spinal vertebrae, thereby increasing spinal stability and allowing nerve roots to properly exit through the spaces between the vertebrae from the spinal cord.
Each thoracic vertebrae has a pair of huge wing-like transverse processes, many of which overlap. The dorsal end of the ribs are remarkably thin and almost fail to make contact with the transverse processes.
The extracellular matrix of bone is laid down by osteoblasts, which secrete both collagen and ground substance. These synthesise collagen within the cell and then secrete collagen fibrils. The collagen fibers rapidly polymerise to form collagen strands. At this stage, they are not yet mineralised, and are called "osteoid".
Cartilaginous fishes (sharks, rays and skates) have cartilaginous jaws. The jaw's surface (in comparison to the vertebrae and gill arches) needs extra strength due to its heavy exposure to physical stress. It has a layer of tiny hexagonal plates called "tesserae", which are crystal blocks of calcium salts arranged as a mosaic. This gives these areas much of the same strength found in the bony tissue found in other animals.
The spine has cervical, thoracic, lumbar and caudal regions with the number of cervical (neck) vertebrae highly variable and especially flexible, but movement is reduced in the anterior thoracic vertebrae and absent in the later vertebrae. The last few are fused with the pelvis to form the synsacrum. The ribs are flattened and the sternum is keeled for the attachment of flight muscles except in the flightless bird orders. The forelimbs are modified into wings. The wings are more or less developed depending on the species; the only known groups that lost their wings are the extinct moa and elephant birds.
|
What type of relationship is parasitism?
|
[
"primordial relationship",
"enzymatic relationship",
"symbiotic relationship",
"hypodermic relationship"
] |
C
|
Parasitism is a symbiotic relationship in which one species benefits and the other species is harmed. The species that benefits is called the parasite. The species that is harmed is called the host. Many species of animals are parasites, at least during some stage of their life cycle. Most animal species are also hosts to one or more parasites.
Parasitism is a kind of symbiosis, a close and persistent long-term biological interaction between a parasite and its host. Unlike saprotrophs, parasites feed on living hosts, though some parasitic fungi, for instance, may continue to feed on hosts they have killed. Unlike commensalism and mutualism, the parasitic relationship harms the host, either feeding on it or, as in the case of intestinal parasites, consuming some of its food. Because parasites interact with other species, they can readily act as vectors of pathogens, causing disease.
In his view, the parallels include the placing of an embryo in the host; its growth in the host; the resulting death of the host; and alternating generations, as in the Digenea (trematodes). The social anthropologist Marika Moisseeff argues that "The parasitical and swarming aspects of insect reproduction make these animals favored villains in Hollywood science fiction. The battle of culture against nature is depicted as an unending combat between humanity and insect-like extraterrestrial species that tend to parasitize human beings in order to reproduce." The Encyclopedia of Science Fiction lists many instances of "parasitism", often causing the host's death.
The parasitologist F. E. G. Cox noted that "Humans are hosts to nearly 300 species of parasitic worms and over 70 species of protozoa, some derived from our primate ancestors and some acquired from the animals we have domesticated or come in contact with during our relatively short history on Earth".One of the largest fields in parasitology, medical parasitology is the subject that deals with the parasites that infect humans, the diseases caused by them, clinical picture and the response generated by humans against them. It is also concerned with the various methods of their diagnosis, treatment and finally their prevention & control. A parasite is an organism that live on or within another organism called the host.
Some parasitoids influence their host's behaviour in ways that favour the propagation of the parasitoid. Parasitoids are found in a variety of taxa across the insect superorder Endopterygota, whose complete metamorphosis may have pre-adapted them for a split lifestyle, with parasitoid larvae and free-living adults. Most are in the Hymenoptera, where the ichneumons and many other parasitoid wasps are highly specialised for a parasitoidal way of life.
Parasitic castration is the strategy, by a parasite, of blocking reproduction by its host, completely or in part, to its own benefit. This is one of six major strategies within parasitism.
|
What two things are used in optical instruments to reflect or refract light?
|
[
"orientations and lenses",
"mirrors and magnifiers",
"prisms and microscopes",
"mirrors and lenses"
] |
D
|
Mirrors and lenses are used in optical instruments to reflect or refract light. Optical instruments include microscopes, telescopes, cameras, and lasers.
In photography and cinematography, a reflector is an improvised or specialised reflective surface used to redirect light towards a given subject or scene.
Two general types of instruments exist: filter fluorometers that use filters to isolate the incident light and fluorescent light and spectrofluorometers that use diffraction grating monochromators to isolate the incident light and fluorescent light. Both types use the following scheme: the light from an excitation source passes through a filter or monochromator, and strikes the sample. A proportion of the incident light is absorbed by the sample, and some of the molecules in the sample fluoresce. The fluorescent light is emitted in all directions.
All refracting telescopes use the same principles. The combination of an objective lens 1 and some type of eyepiece 2 is used to gather more light than the human eye is able to collect on its own, focus it 5, and present the viewer with a brighter, clearer, and magnified virtual image 6. The objective in a refracting telescope refracts or bends light. This refraction causes parallel light rays to converge at a focal point; while those not parallel converge upon a focal plane.
Aconic reflectors are used in ultraviolet light UV curing devices to smooth light density for a more uniform curing pattern. They can be used to mask hot spots generated by the lamp envelope and cold areas created by shadows. They can be used to illuminate a specific shape at a given distance.
An optical coating is one or more thin layers of material deposited on an optical component such as a lens, prism or mirror, which alters the way in which the optic reflects and transmits light. These coatings have become a key technology in the field of optics. One type of optical coating is an anti-reflective coating, which reduces unwanted reflections from surfaces, and is commonly used on spectacle and camera lenses. Another type is the high-reflector coating, which can be used to produce mirrors that reflect greater than 99.99% of the light that falls on them. More complex optical coatings exhibit high reflection over some range of wavelengths, and anti-reflection over another range, allowing the production of dichroic thin-film filters.
|
What physical property of matter reflects how closely packed the particles of matter are?
|
[
"makeup",
"build up",
"density",
"mass"
] |
C
|
Density is an important physical property of matter. It reflects how closely packed the particles of matter are.
Assume that the molecules of two different substances are approximately the same size, and regard space as subdivided into a square lattice whose cells are the size of the molecules. (In fact, any lattice would do, including close packing.) This is a crystal-like conceptual model to identify the molecular centers of mass. If the two phases are liquids, there is no spatial uncertainty in each one individually.
The interstellar medium is matter that occupies the space between star systems in a galaxy. 99% of this matter is gaseous – hydrogen, helium, and smaller quantities of other ionized elements such as oxygen. The other 1% is dust particles, thought to be mainly graphite, silicates, and ices. Clouds of the dust and gas are referred to as nebulae.
Dust particles, aided by ices and organics, form "aggregates" (less often, "agglomerates") of 30 to hundreds of micrometers. These are fluffy, due to the imperfect packing of cluster-type (large) dust particles, and their subsequent, imperfect packing into aggregates.The next size category is pebbles, of millimeters to centimeters scale. Pebbles were inferred at 103P/Hartley 2, and imaged directly at 67P/Churyumov-Gerasimenko. Astrophysical use of the word "pebble" differs from its geological meaning.
"The concept of matter has changed in response to new scientific discoveries. Thus materialism has no definite content independent of the particular theory of matter on which it is based. According to Noam Chomsky, any property can be considered material, if one defines matter such that it has that property.The philosophical materialist Gustavo Bueno uses a more precise term than matter, the stroma.
As heat is added to this substance it melts into a liquid at its melting point, boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized that they leave their parent atoms. Forms of matter that are not composed of molecules and are organized by different forces can also be considered different states of matter.
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What type of boiling point do nonmetals normally have?
|
[
"even",
"high",
"low",
"odd"
] |
C
|
Properties of nonmetals include a relatively low boiling point, so many nonmetals are gases. Nonmetals are also poor conductors of heat, and solid nonmetals are dull and brittle.
Non-covalent interactions have a significant effect on the boiling point of a liquid. Boiling point is defined as the temperature at which the vapor pressure of a liquid is equal to the pressure surrounding the liquid. More simply, it is the temperature at which a liquid becomes a gas. As one might expect, the stronger the non-covalent interactions present for a substance, the higher its boiling point.
Nonmetals have open structures (unless solidified from gaseous or liquid forms); tend to gain or share electrons when they react with other substances; and do not form distinctly basic oxides. Most are gases at room temperature; have relatively low densities; are poor electrical and thermal conductors; have relatively high ionisation energies and electronegativities; form acidic oxides; and are found naturally in uncombined states in large amounts. Some nonmetals (C, black P, S, and Se) are brittle solids at room temperature (although each of these also have malleable, pliable or ductile allotropes). From left to right in the periodic table, the nonmetals can be divided into the reactive nonmetals and the noble gases. The reactive nonmetals near the metalloids show some incipient metallic character, such as the metallic appearance of graphite, black phosphorus, selenium and iodine. The noble gases are almost completely inert.
Many substances normally stored as liquids, such as CO2, propane, and other similar industrial gases have boiling temperatures far below room temperature when at atmospheric pressure. In the case of water, a BLEVE could occur if a pressurized chamber of water is heated far beyond the standard 100 °C (212 °F). That container, because the boiling water pressurizes it, must be capable of holding liquid water at very high temperatures.
For example, the melting point of silicon at ambient pressure (0.1 MPa) is 1415 °C, but at pressures in excess of 10 GPa it decreases to 1000 °C.Melting points are often used to characterize organic and inorganic compounds and to ascertain their purity. The melting point of a pure substance is always higher and has a smaller range than the melting point of an impure substance or, more generally, of mixtures. The higher the quantity of other components, the lower the melting point and the broader will be the melting point range, often referred to as the "pasty range".
Accordingly, ITS–90 uses numerous defined points, all of which are based on various thermodynamic equilibrium states of fourteen pure chemical elements and one compound (water). Most of the defined points are based on a phase transition; specifically the melting/freezing point of a pure chemical element. However, the deepest cryogenic points are based exclusively on the vapor pressure/temperature relationship of helium and its isotopes whereas the remainder of its cold points (those less than room temperature) are based on triple points.
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Coxal glands collect liquid waste from what?
|
[
"lungs",
"plasma",
"blood",
"heart"
] |
C
|
Some arthropods have special excretory structures. They are called coxal glands and Malpighian tubules . Coxal glands collect and concentrate liquid waste from blood. They excrete the waste from the body through a pore. Malphigian tubules carry waste from the digestive tract to the anus. The waste is excreted through the anus.
The nervous system consists of two nerve cords which run the length of the body, with two ganglia and two transverse commissures in most of the body segments.Gas exchange is thought to take place through the entire body surface, but especially that of the phyllopodia and their associated gills, which may also be responsible for osmotic regulation. Two coiled glands at the bases of the maxillae are used to excrete nitrogenous waste, typically in the form of urea. Most of the animal's nitrogenous waste is, however, in the form of ammonia, which probably diffuses into the environment through the phyllopodia and gills.
The endodermal cells primarily generate the lining and glands of the digestive tube
The pharyngeal nephridia are attached to the fourth, fifth and sixth segments. The waste in the coelom fluid from a forward segment is drawn in by the beating of cilia of the nephrostome. From there it is carried through the septum (wall) via a tube which forms a series of loops entwined by blood capillaries that also transfer waste into the tubule of the nephrostome. The excretory wastes are then finally discharged through a pore on the worm's side.
Archaeocytes transport food packaged in vesicles from cells that directly digest food to those that do not. At least one species of sponge has internal fibers that function as tracks for use by nutrient-carrying archaeocytes, and these tracks also move inert objects.It used to be claimed that glass sponges could live on nutrients dissolved in sea water and were very averse to silt. However, a study in 2007 found no evidence of this and concluded that they extract bacteria and other micro-organisms from water very efficiently (about 79%) and process suspended sediment grains to extract such prey. Collar bodies digest food and distribute it wrapped in vesicles that are transported by dynein "motor" molecules along bundles of microtubules that run throughout the syncytium.Sponges' cells absorb oxygen by diffusion from water into cells as water flows through body, into which carbon dioxide and other soluble waste products such as ammonia also diffuse. Archeocytes remove mineral particles that threaten to block the ostia, transport them through the mesohyl and generally dump them into the outgoing water current, although some species incorporate them into their skeletons.
With the help of digestive enzymes from the penetration glands, they penetrate the intestinal mucosa to enter blood and lymphatic vessels. They move along the general circulatory system to various organs, and large numbers are cleared in the liver. The surviving oncospheres preferentially migrate to striated muscles, as well as the brain, liver, and other tissues, where they settle to form cysts — cysticerci.
|
The main organs of the cardiovascular system are the blood vessels and what else?
|
[
"alveoli",
"capillaries",
"lung",
"heart"
] |
D
|
The main organs of the cardiovascular system are the heart and blood vessels. Both organs contain valves. Valves also are found in plumbing systems. They can be turned on or off to control the flow of water.
Blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from the tissues.
Vascular endothelial cells line the entire circulatory system, from the heart to the smallest capillaries. These cells have unique functions that include fluid filtration, such as in the glomerulus of the kidney, blood vessel tone, hemostasis, neutrophil recruitment, and hormone trafficking. Endothelium of the interior surfaces of the heart chambers is called endocardium. An impaired function can lead to serious health issues throughout the body.
Systemic arteries can be subdivided into two types—muscular and elastic—according to the relative compositions of elastic and muscle tissue in their tunica media as well as their size and the makeup of the internal and external elastic lamina. The larger arteries (>10 mm diameter) are generally elastic and the smaller ones (0.1–10 mm) tend to be muscular. Systemic arteries deliver blood to the arterioles, and then to the capillaries, where nutrients and gases are exchanged. After traveling from the aorta, blood travels through peripheral arteries into smaller arteries called arterioles, and eventually to capillaries. Arterioles help in regulating blood pressure by the variable contraction of the smooth muscle of their walls, and deliver blood to the capillaries.
The circulatory systems of all vertebrates are closed, just as in humans. Still, the systems of fish, amphibians, reptiles, and birds show various stages of the evolution of the circulatory system. In fish, the system has only one circuit, with the blood being pumped through the capillaries of the gills and on to the capillaries of the body tissues. This is known as single cycle circulation.
The renal circulation is the blood supply to the kidneys, contains many specialized blood vessels and receives around 20% of the cardiac output. It branches from the abdominal aorta and returns blood to the ascending inferior vena cava.
|
What substance flows over the land from precipitation or melting snow or ice?
|
[
"nitrogen",
"lava",
"water",
"air"
] |
C
|
water that flows over the land from precipitation or melting snow or ice.
Streams – a major part of Earth's water cycle – shape the landscape, carve rocks, transport sediments, and replenish groundwater. At high elevations or latitudes, snow is compacted and recrystallized over hundreds or thousands of years to form glaciers, which can be so heavy that they warp the Earth's crust. About 30 percent of land has a dry climate, due to losing more water through evaporation than it gains from precipitation.
Ice sheets and glaciers are flowing ice masses that rest on solid land. They are controlled by snow accumulation, surface and basal melt, calving into surrounding oceans or lakes and internal dynamics. The latter results from gravity-driven creep flow ("glacial flow") within the ice body and sliding on the underlying land, which leads to thinning and horizontal spreading.
Snow and/or frost forms on dunes at times. Because of the high salt content, that snow/ice melts at a lower temperature. When the water evaporates, it leaves behind hydrated sulfate, opal, iron oxide, and other hydrated minerals.
Frost heaving requires a frost-susceptible soil, a continual supply of water below (a water table) and freezing temperatures, penetrating into the soil. Frost-susceptible soils are those with pore sizes between particles and particle surface area that promote capillary flow. Silty and loamy soil types, which contain fine particles, are examples of frost-susceptible soils. Many agencies classify materials as being frost susceptible if 10 percent or more constituent particles pass through a 0.075 mm (No. 200) sieve or 3 percent or more pass through a 0.02 mm (No. 635) sieve.
In wet deposition, atmospheric hydrometeors (rain drops, snow etc.) scavenge aerosol particles. This means that wet deposition is gravitational, Brownian and/or turbulent coagulation with water droplets. Different types of wet deposition include: Below-cloud scavenging. This happens when falling rain droplets or snow particles collide with aerosol particles through Brownian diffusion, interception, impaction and turbulent diffusion.
|
Most turtle bodies are covered by a special bony or cartilaginous shell developed from their what?
|
[
"spines",
"tails",
"fins",
"ribs"
] |
D
|
Most turtle bodies are covered by a special bony or cartilaginous shell developed from their ribs.
Sea turtles have a carapace and plastron of bone and cartilage which is developed from their ribs. Infrequently a turtle "shell" will wash up on a beach.
The keeled box turtle's upper shell (carapace) has three large, raised ridges and is serrated on the back end. The lower shell (plastron) is different variations of brown in color, ranging from light brown to dark brown. The upper jaw is strong, while the snout is short and curved.
The neck cannot be pulled into the shell. The sheath of the turtle's upper jaw possesses a denticulated edge, while its lower jaw has stronger, serrated, more defined denticulation. The dorsal surface of the turtle's head has a single pair of prefrontal scales.
Leatherback turtles have the most hydrodynamic body of any sea turtle, with a large, teardrop-shaped body. A large pair of front flippers powers the turtles through the water. Like other sea turtles, the leatherback has flattened forelimbs adapted for swimming in the open ocean. Claws are absent from both pairs of flippers.
Cartilaginous fishes (sharks, rays and skates) have cartilaginous jaws. The jaw's surface (in comparison to the vertebrae and gill arches) needs extra strength due to its heavy exposure to physical stress. It has a layer of tiny hexagonal plates called "tesserae", which are crystal blocks of calcium salts arranged as a mosaic. This gives these areas much of the same strength found in the bony tissue found in other animals.
|
What device uses an electromagnet to change electrical energy to kinetic energy?
|
[
"public motor",
"melodic motor",
"Magnetic motor.",
"electric motor"
] |
D
|
An electric motor is a device that uses an electromagnet to change electrical energy to kinetic energy. When current flows through the motor, the electromagnet rotates, causing a shaft to rotate as well. The rotating shaft moves other parts of the device.
(The spinning ferromagnet is not a "non-moving ferromagnet"). Switching the polarity of an electromagnet or system of electromagnets can levitate a system by continuous expenditure of energy.
Devices that can provide emf include electrochemical cells, thermoelectric devices, solar cells, photodiodes, electrical generators, inductors, transformers and even Van de Graaff generators. In nature, emf is generated when magnetic field fluctuations occur through a surface. For example, the shifting of the Earth's magnetic field during a geomagnetic storm induces currents in an electrical grid as the lines of the magnetic field are shifted about and cut across the conductors. In a battery, the charge separation that gives rise to a potential difference (voltage) between the terminals is accomplished by chemical reactions at the electrodes that convert chemical potential energy into electromagnetic potential energy.
Thus the moving conductor experiences a drag force from the magnet that opposes its motion, proportional to its velocity. The kinetic energy of the moving object is dissipated as heat generated by the current flowing through the electrical resistance of the conductor. In an eddy current brake the magnetic field may be created by a permanent magnet or an electromagnet.
The use of superconductor magnets can reduce the electromagnets' energy consumption. A 50-ton Transrapid maglev vehicle can lift an additional 20 tons, for a total of 70 tons, which consumes 70–140 kilowatts (94–188 hp). Most energy use for the TRI is for propulsion and overcoming air resistance at speeds over 100 miles per hour (160 km/h).
Ferromagnetic-core or iron-core inductors use a magnetic core made of a ferromagnetic or ferrimagnetic material such as iron or ferrite to increase the inductance. A magnetic core can increase the inductance of a coil by a factor of several thousand, by increasing the magnetic field due to its higher magnetic permeability. However the magnetic properties of the core material cause several side effects which alter the behavior of the inductor and require special construction: Core lossesA time-varying current in a ferromagnetic inductor, which causes a time-varying magnetic field in its core, causes energy losses in the core material that are dissipated as heat, due to two processes: Eddy currentsFrom Faraday's law of induction, the changing magnetic field can induce circulating loops of electric current in the conductive metal core. The energy in these currents is dissipated as heat in the resistance of the core material.
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