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What substances, which are distinct from acids and bases, form when ions form ionic bonds?
|
[
"oils",
"salts",
"vitamins",
"water molecules"
] |
B
|
Salts Recall that salts are formed when ions form ionic bonds. In these reactions, one atom gives up one or more electrons, and thus becomes positively charged, whereas the other accepts one or more electrons and becomes negatively charged. You can now define a salt as a substance that, when dissolved in water, dissociates into ions other than H+ or OH–. This fact is important in distinguishing salts from acids and bases, discussed next. A typical salt, NaCl, dissociates completely in water (Figure 2.15). The positive and negative regions on the water molecule (the hydrogen and oxygen ends respectively) attract the negative chloride and positive sodium ions, pulling them away from each other. Again, whereas nonpolar and polar covalently bonded compounds break apart into molecules in solution, salts dissociate into ions. These ions are electrolytes; they are capable of conducting an electrical current in solution. This property is critical to the function of ions in transmitting nerve impulses and prompting muscle contraction.
Substances that are hydrophobic ('water-fearing') do not dissolve well in water, whereas those that are hydrophilic ('water-friendly') do. An example of a hydrophilic substance is sodium chloride. In an aqueous solution the hydrogen ions (H+) and hydroxide ions (OH−) are in Arrhenius balance ( = Kw = 1 x 10−14 at 298 K). Acids and bases are aqueous solutions, as part of their Arrhenius definitions. An example of an Arrhenius acid is hydrogen chloride (HCl) because of its dissociation of the hydrogen ion when dissolved in water. Sodium hydroxide (NaOH) is an Arrhenius base because it dissociates the hydroxide ion when it is dissolved in water.Aqueous solutions may contain, especially in the alkaline zone or subjected to radiolysis, hydrated atomic hydrogen and hydrated electrons.
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.
Chemicals or substances having the property of an acid are said to be acidic. Common aqueous acids include hydrochloric acid (a solution of hydrogen chloride that is found in gastric acid in the stomach and activates digestive enzymes), acetic acid (vinegar is a dilute aqueous solution of this liquid), sulfuric acid (used in car batteries), and citric acid (found in citrus fruits). As these examples show, acids (in the colloquial sense) can be solutions or pure substances, and can be derived from acids (in the strict sense) that are solids, liquids, or gases.
In the case of a non-ionic compound the chemical bonds are non-ionic such meaning the compound will probably not dissolve in water or another polar solvent. Many non-ionic compounds have chemical bonds that share the electron density that binds them together. This type of chemical bond is either a non-polar covalent bond or a polar covalent bond.
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).
|
What is the name for biochemical compounds that consist of one or more chains of small molecules called amino acids?
|
[
"proteins",
"lipids",
"protons",
"hormones"
] |
A
|
Proteins are biochemical compounds that consist of one or more chains of small molecules called amino acids. Amino acids are the monomers of proteins. There are only about 20 different amino acids. The sequence of amino acids in chains and the number of chains in a protein determine the protein’s shape. Shapes may be very complex. You can learn more about the shapes of proteins at this link:.
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the α-amino acids, from which proteins are composed. Only 22 α-amino acids appear in the genetic code of all life.Amino acids can be classified according to the locations of the core structural functional groups, as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, ionization, and side chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid residues form the second-largest component (water being the largest) of human muscles and other tissues.
amineAn organic compound containing nitrogen, derived from ammonia, NH3, by replacing one or more hydrogen atoms by as many hydrocarbon radicals. amino acidOrganic compounds that contain the amino (NH2) group and the carboxyl (COOH) group. Amino acids are the "building stones" of proteins.
Diethylamine is the smallest and simplest molecule that features a supramolecular helix as its lowest energy aggregate. Other similarly sized hydrogen-bonding molecules favor cyclic structures.
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 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.
|
What are the ionic compounds that produce negative hydroxide ions when dissolved in water?
|
[
"isotopes",
"acids",
"bases",
"enzymes"
] |
C
|
Bases are ionic compounds that produce negative hydroxide ions (OH - ) when dissolved in water. An ionic compound contains positive metal ions and negative nonmetal ions held together by ionic bonds. (Ions are atoms that have become charged particles because they have either lost or gained electrons. ) An example of a base is sodium hydroxide (NaOH). When it dissolves in water, it produces negative hydroxide ions and positive sodium ions (Na + ). This can be represented by the equation:.
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).
Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until a precipitate of aluminium hydroxide, Al(OH)3, forms. This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Increasing the pH even further leads to the hydroxide dissolving again as aluminate, −, is formed.
Salts can be classified in a variety of ways. Salts that produce hydroxide ions when dissolved in water are called alkali salts and salts that produce hydrogen ions when dissolved in water are called acid salts. Neutral salts are those salts that are neither acidic nor alkaline. Zwitterions contain an anionic and a cationic centre in the same molecule, but are not considered salts. Examples of zwitterions are amino acids, many metabolites, peptides, and proteins.
Because they commonly consist of ions in solution, the electrolytes are often known as "ionic solutions", but molten and solid electrolytes are also possible. Water is passed between an anode and a cathode. Ion-selective membranes allow the positive ions to separate from the water toward the negative electrode and the negative ions toward the positive electrode. As a result, the ions cannot escape the cell, and deionized water is produced.
Substances that are hydrophobic ('water-fearing') do not dissolve well in water, whereas those that are hydrophilic ('water-friendly') do. An example of a hydrophilic substance is sodium chloride. In an aqueous solution the hydrogen ions (H+) and hydroxide ions (OH−) are in Arrhenius balance ( = Kw = 1 x 10−14 at 298 K). Acids and bases are aqueous solutions, as part of their Arrhenius definitions. An example of an Arrhenius acid is hydrogen chloride (HCl) because of its dissociation of the hydrogen ion when dissolved in water. Sodium hydroxide (NaOH) is an Arrhenius base because it dissociates the hydroxide ion when it is dissolved in water.Aqueous solutions may contain, especially in the alkaline zone or subjected to radiolysis, hydrated atomic hydrogen and hydrated electrons.
|
The atomic number of tungsten is 74. therefore, in a neutral atom of tungsten, there are 74 electrons. the atomic number of argon is 18. therefore, in a neutral atom of argon, there are how many electrons?
|
[
"74",
"18",
"9",
"36"
] |
B
|
The atomic number of tungsten is 74. Therefore, in a neutral atom of tungsten, there are 74 electrons. The atomic number of argon is 18. Therefore, in a neutral atom of argon, there are 18 electrons.
In argon the electron configuration is 5f2(δφ) whereas in neon it is 5f17s1 (the state 3H4g compared to 3Φ2u). This is because the argon atoms have a larger antibonding interaction with the 7s1 electron, forcing it into a different subshell. The argonated compound has a stretching frequency of 776 cm−1 compared to 914.8 cm−1 in neon. The argon uranium dioxide molecule is likely UO2Ar5.
This page shows the electron configurations of the neutral gaseous atoms in their ground states. For each atom the subshells are given first in concise form, then with all subshells written out, followed by the number of electrons per shell. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below. As an approximate rule, electron configurations are given by the Aufbau principle and the Madelung rule.
Electrons were found to be even smaller. Later, scientists found the expected number of electrons (the same as the atomic number) in an atom by using X-rays. When an X-ray passes through an atom, some of it is scattered, while the rest passes through the atom. Since the X-ray loses its intensity primarily due to scattering at electrons, by noting the rate of decrease in X-ray intensity, the number of electrons contained in an atom can be accurately estimated.
In two dimension the Ru atoms form a tetragonal lattice with the tin atoms appearing as triangular units in the Ru channels.The occurrence of a LCP phase can be predicted by the so-called 14 electron rule. In it the total number of valence electrons per transition metal atom is 14. == References ==
Fluorine atoms have nine electrons, one fewer than neon, and electron configuration 1s22s22p5: two electrons in a filled inner shell and seven in an outer shell requiring one more to be filled. The outer electrons are ineffective at nuclear shielding, and experience a high effective nuclear charge of 9 − 2 = 7; this affects the atom's physical properties.Fluorine's first ionization energy is third-highest among all elements, behind helium and neon, which complicates the removal of electrons from neutral fluorine atoms. It also has a high electron affinity, second only to chlorine, and tends to capture an electron to become isoelectronic with the noble gas neon; it has the highest electronegativity of any reactive element. Fluorine atoms have a small covalent radius of around 60 picometers, similar to those of its period neighbors oxygen and neon.
|
What is the apparatus used for carrying out an electrolysis reaction?
|
[
"Golgi apparatus",
"catalyst",
"an aqueous cell",
"an electrolytic cell"
] |
D
|
An electrolytic cell is the apparatus used for carrying out an electrolysis reaction. In an electrolytic cell, electric current is applied to provide a source of electrons for driving the reaction in a nonspontaneous direction. In a voltaic cell, the reaction goes in a direction that releases electrons spontaneously. In an electrolytic cell, the input of electrons from an external source forces the reaction to go in the opposite direction.
Electrolysis is the passing of a direct electric current through an electrolyte producing chemical reactions at the electrodes and decomposition of the materials. The main components required to achieve electrolysis are an electrolyte, electrodes, and an external power source. A partition (e.g. an ion-exchange membrane or a salt bridge) is optional to keep the products from diffusing to the vicinity of the opposite electrode. The electrolyte is a chemical substance which contains free ions and carries electric current (e.g. an ion-conducting polymer, solution, or a ionic liquid compound).
Electrolytic cells are often used to decompose chemical compounds, in a process called electrolysis— with electro meaning electricity and the Greek word lysis means to break up. Important examples of electrolysis are the decomposition of water into hydrogen and oxygen, and bauxite into aluminum and other chemicals. Electroplating (e.g., of copper, silver, nickel, or chromium) is done using an electrolytic cell. Electrolysis is a technique that uses a direct electric current (DC).
The microbial electrolytic process uses wastewater as a source of charged ions and outputs hydrogen gas through the use of the microbial electrolysis cell. The wastewater itself provides electrolytes and is used to dissolve minerals. It is in the wastewater where reactions occur that bind CO2 molecules to make new substances.On the anode, microorganisms called exoelectrogens interact with organic compounds to split hydrogen and produce CO2. The resulting electrons travel through the circuit to the cathode, where they reduce water, to produce H2 gas and OH− ions.
Bulk electrolysis is also known as potentiostatic coulometry or controlled potential coulometry. The experiment is a form of coulometry which generally employs a three electrode system controlled by a potentiostat. In the experiment the working electrode is held at a constant potential (volts) and current (amps) is monitored over time (seconds). In a properly run experiment an analyte is quantitatively converted from its original oxidation state to a new oxidation state, either reduced or oxidized.
This effectively allows the electrolyser to operate at more than 100% electrical efficiency. In electrochemical systems this means that heat must be supplied to the reactor to sustain the reaction. In this way thermal energy can be used for part of the electrolysis energy requirement.
|
What two ways may light be transmitted?
|
[
"magnified or scattered",
"refracted or scattered",
"reflected or refracted",
"absorption and refraction"
] |
B
|
Transmitted light may be refracted or scattered. When does each process occur?.
Transmittance is a measure of how much visible light is passed by the glass expressed as a fraction. Some of the light will also be absorbed and reflected. Some types of light include radio waves. Notably, many low-e glass and semi-reflective metalised coatings greatly attenuate Wi-Fi and cell phone signals.
Moving through a tunnel. Communication with light. Observation of colours.
Colour light signals come in two forms. The most prevalent form is the multi-unit type, with separate lights and lenses for each colour, in the manner of a traffic light. Hoods and shields are generally provided to shade the lights from sunlight which could cause false indications.
One of the main benefits of using the optical techniques which make up biophotonics is that they preserve the integrity of the biological cells being examined.Biophotonics has therefore become the established general term for all techniques that deal with the interaction between biological items and photons. This refers to emission, detection, absorption, reflection, modification, and creation of radiation from biomolecular, cells, tissues, organisms, and biomaterials. Areas of application are life science, medicine, agriculture, and environmental science. Similar to the differentiation between "electric" and "electronics," a difference can be made between applications such as therapy and surgery, which use light mainly to transfer energy, and applications such as diagnostics, which use light to excite matter and to transfer information back to the operator. In most cases, the term biophotonics refers to the latter type of application.
Not all of the intercepted light is transmitted into the panel; some is reflected at its surface. The amount reflected depends on both the refractive index of the surface material and the angle of incidence of the incoming light. The amount reflected also differs depending on the polarization of the incoming light. Incoming sunlight is a mixture of all polarizations, with equal amounts in direct sunlight.
|
Triggered by changes in the environment, migration and hibernation occur as cycles on what temporal basis?
|
[
"annual",
"bi-annually",
"seasonally",
"monthly"
] |
A
|
Examples of behaviors with annual cycles include migration and hibernation. Both are innate behaviors. They are triggered by changes in the environment, such as the days growing shorter in the fall.
Many other important cycles are also studied, including: Infradian rhythms, which are cycles longer than a day. Examples include circannual or annual cycles that govern migration or reproduction cycles in many plants and animals, or the human menstrual cycle. Ultradian rhythms, which are cycles shorter than 24 hours, such as the 90-minute REM cycle, the 4-hour nasal cycle, or the 3-hour cycle of growth hormone production. Tidal rhythms, commonly observed in marine life, which follow the roughly 12.4-hour transition from high to low tide and back.
It is thought to have originally evolved in three stages. The first is development of neuroendocrine control over bodily functions, the second is pairing of that to environmental changes—in this case metabolic rates decreasing in response to colder temperatures—and the third is the pairing of these controls with reliable seasonal indicators within the arthropod, like biological timers. From these steps, arthropods developed a seasonal diapause, where many of their biological functions end up paired with a seasonal rhythm within the organism. This is a very similar mechanism to the evolution of insect migration, where instead of bodily functions like metabolism getting paired with seasonal indicators, movement patterns would be paired with seasonal indicators.
The timing of phenological events such as flowering are often related to environmental variables such as temperature. Changing environments are therefore expected to lead to changes in life cycle events, and these have been recorded for many species of plants. These changes have the potential to lead to the asynchrony between species, or to change competition between plants. Both the insect pollinators and plant populations will eventually become extinct due to the uneven and confusing connection that is caused by the change of climate.
To achieve this energy saving, an endothermic animal decreases its metabolic rate and thereby its body temperature. Hibernation may last days, weeks, or months—depending on the species, ambient temperature, time of year, and the individual's body-condition. Before entering hibernation, animals need to store enough energy to last through the duration of their dormant period, possibly as long as an entire winter.
Changes affecting algae, plankton, fish and zooplankton because rising water temperatures and changes in: ice cover salinity oxygen levels water circulationWith a very high confidence (about a 9 in 10 chance to be correct) WGII asserts that climate change is affecting terrestrial biological systems in that: Spring events such as the unfolding of leaves, laying of eggs, and migration are happening earlier. There are poleward and upward (to higher altitude) shifts in ranges of plant and animal species.WGII also states that the ocean has become more acidic because it has absorbed human-caused carbon dioxide. Ocean pH has dropped by 0.1, but how this affects marine life is not documented.
|
What pair of tubes that extends toward the ovaries features a fringelike structure that sweeps eggs inside?
|
[
"golgi apparatus",
"ovarian tubes",
"vas deferens",
"fallopian tubes"
] |
D
|
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.
Of all the fimbriae, one fimbria known as the ovarian fimbria is long enough to reach and make contact with the near part of the ovary during ovulation. The fimbriae have a higher density of blood vessels than the other parts of the tube, and the ovarian fimbria is seen to have an even higher density.An ovary is not directly connected to its adjacent fallopian tube. When ovulation is about to occur, the sex hormones activate the fimbriae, causing them to swell with blood, extend, and hit the ovary in a gentle, sweeping motion. An oocyte is released from the ovary into the peritoneal cavity and the cilia of the fimbriae sweep it into the fallopian tube.
The embryonic disc becomes oval and then pear-shaped, the wider end being directed forward. Towards the narrow, posterior end, an opaque primitive streak, is formed and extends along the middle of the disc for about half of its length; at the anterior end of the streak there is a knob-like thickening termed the primitive node or knot, (known as Hensen's knot in birds). A shallow groove, the primitive groove, appears on the surface of the streak, and the anterior end of this groove communicates by means of an aperture, the blastopore, with the yolk sac. The primitive streak is produced by a thickening of the axial part of the ectoderm, the cells of which multiply, grow downward, and blend with those of the subjacent endoderm.
It is presumed to be oviparous (egg laying).
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.
pendulous Hanging, for example an ovule attached to a placenta on the top of the ovary. Compare suspended. penicillate Tufted like an artist's brush; with long hairs toward one end.
|
In most animals, what sense is related to balance or equilibrium?
|
[
"vision",
"tasting",
"hearing",
"feeling"
] |
C
|
Balance denotes visual balance, not the actual ability to stand upright. Proportion refers to the various parts of the three-dimensional object.
A balance disorder is a condition that makes a person feel nausea, disorientation or dizziness as if moving, spinning or falling even though steady. Balance disorder can be caused by medication, problems of the inner ear or the brain.
Balancing is the methodical regulation of system fluid flows (air or water) through the use of acceptable procedures to achieve the desired or specified design airflow or water flow. When beginning the balance of a system, you must locate the terminal with the least amount of flow in regards to the engineer's drawing. Once the "low" terminal has been located, you can then proceed to adjust all other diffusers/grilles (air) or circuit balancing valves (water) to proportionally match the original "low" terminal. There must be at least one terminal that is wide open to achieve optimum efficiency. == Notes ==
In mechanics, an equilibrant force is a force which brings a body into mechanical equilibrium. According to Newton's second law, a body has zero acceleration when the vector sum of all the forces acting upon it is zero: ∑ F = m a ; ∑ F = 0 ⇒ a = 0 {\displaystyle \sum \mathbf {F} =m\mathbf {a} ;\quad \sum \mathbf {F} =0\ \ \Rightarrow \ \ \mathbf {a} =0} Therefore, an equilibrant force is equal in magnitude and opposite in direction to the resultant of all the other forces acting on a body. The term has been attested since the late 19th century.
Balance (ability), equilibrioception – the sense that allows an organism to sense body movement, direction, and acceleration, and to attain and maintain postural equilibrium and balance. Also: vestibular nerve Thermoception – sense of heat and the absence of heat (cold) by the skin and including internal skin passages, or, rather, the heat flux (the rate of heat flow) in these areas. Proprioception – provides the information on the relative position of the parts of the body. Proprioception and touch are related in subtle ways, and their impairment results in surprising and deep deficits in perception and action.
|
Terminal pods are located at the end of what?
|
[
"fruits",
"leaves",
"spines",
"stems"
] |
D
|
Mendel investigated seven different characteristics in pea plants. In this chart, cotyledons refer to the tiny leaves inside seeds. Axial pods are located along the stems. Terminal pods are located at the ends of the stems.
They are placed on both the upper band of the ring and the quadrants of each of the two cloverleaf-shaped terminals. The terminals are about 2.5 cm (1 in) apart, and separated from both the ring-head and each other by raised borders lined with gold.The brooch is in relatively good condition; some of the settings for decorative studs in the head and terminals, made from red glass and amber, are missing. Its reverse is rather flat and unembellished.
The concourse, in the terminal's center, leads north to its train shed as well as an escalator, placed centrally on the north wall, leading up to the MetLife Building. There is only one entrance from the south end – a wide bridge spanning over the Oyster Bar ramps leading into Vanderbilt Hall. Passageways also lead from the west and east ends of the concourse, on either side of the west and east sets of stairs. These passageways lie underneath the east and west balconies, with shops and ticket machines along the walls, and lead to additional passageways that largely make up the station interior.
: 14 A "podetium" (plural: podetia) is a lichenized stalk-like structure of the fruiting body rising from the thallus, associated with some fungi that produce a fungal apothecium. Since it is part of the reproductive tissue, podetia are not considered part of the main body (thallus), but may be visually prominent. The podetium may be branched, and sometimes cup-like.
The Main Concourse is the primary concourse of Grand Central Terminal, a railway station in Midtown Manhattan, New York City. The space is located at the center of the terminal's station building. The distinctive architecture and design of the Main Concourse helped earn several landmark designations for the station, including as a National Historic Landmark. The concourse, along with some other interior spaces, has been protected as an interior New York City Landmark since 1980.
The peptides released at the median eminence enter the primary plexus capillaries. From there, they are transported to the anterior pituitary via hypophyseal portal veins to the secondary plexus.
|
What forms when the spores from two parents fuse during sexual reproduction?
|
[
"xerophyte",
"zygospore",
"spirogyra",
"monospore"
] |
B
|
Sexual reproduction occurs when spores from two parents fuse and form a zygospore.
Reproductive spores are generally the result of cell division, most commonly meiosis (e.g. in plant sporophytes). Sporic meiosis is needed to complete the sexual life cycle of the organisms using it. In some cases, sporogenesis occurs via mitosis (e.g. in some fungi and algae). Mitotic sporogenesis is a form of asexual reproduction.
Powdery mildew fungi reproduce both sexually and asexually. Sexual reproduction occurs via chasmothecia (formerly cleistothecium), a type of ascocarp in which genetic recombination takes place. Within each ascocarp are several asci.
Sexual reproduction commonly occurs in two fundamentally different ways in fungi. These are outcrossing (in heterothallic fungi) in which two different individuals contribute nuclei to form a zygote, and self-fertilization or selfing (in homothallic fungi) in which both nuclei are derived from the same individual. Homothallism in fungi can be defined as the capability of an individual spore to produce a sexually reproducing colony when propagated in isolation.
The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result of contact between hyphae of male antheridia and female oogonia; these spores can overwinter and are known as resting spores. : 409 Asexual reproduction involves the formation of chlamydospores and sporangia, producing motile zoospores.
Within marine centric diatoms, resting spore formation has been most commonly observed from a vegetative parent cell, but some species have been noted to require an auxospore parent cell, which is the product of sexual reproduction.The formation of resting spores is product of two acytokinetic divisions of the parent cell, wherein the cytoplasm of the daughter cells is shared. The resting spores produced may be either exogeneous (mature spore has no contact with parent cell), endogenous (completely enclosed within the parent cell), or semi-endogenous (only the hypovalve of the resting spore enclosed within the parent thecae). The common characteristic of diatom resting spores is a thick silica frustule. Generally, the frustule will be morphologically similar to the vegetative cell, but it can differ greatly. The frustule itself may be with or without a cell girdle, which dictate alternate germination processes, whereby the thecae of resting spores with girdles become the hypotheca and both valves are shed when the girdle is absent.
|
What is the name of the galaxy we live in?
|
[
"Centaurus A",
"Andromeda",
"milky way",
"Bode's Galaxy"
] |
C
|
Like other spiral galaxies, our galaxy has a disk, a central bulge, and spiral arms. The disk is about 100,000 light-years across and 3,000 light-years thick. Most of the Galaxy’s gas, dust, young stars, and open clusters are in the disk.
The name "Galaxy X" was coined in 2011 in analogy to Planet X.
However, this definition should be used as a guide only, as larger and more massive galaxy systems are sometimes classified as galaxy groups. Groups are the most common structures of galaxies in the universe, comprising at least 50% of the galaxies in the local universe. Groups have a mass range between those of the very large elliptical galaxies and clusters of galaxies.Our own galaxy, the Milky Way, is contained in the Local Group of more than 54 galaxies.In July 2017 S. Paul, R. S. John et al. defined clear distinguishing parameters for classifying galaxy aggregations as ‘galaxy groups’ and ‘clusters’ on the basis of scaling laws that they followed. According to this paper, galaxy aggregations less massive than 8 × 1013 solar masses are classified as galaxy groups.
Messier object M31, a magnitude 4.5 galaxy in the constellation Andromeda. It is also known as the Andromeda Galaxy, and is readily visible to the naked eye in a modestly dark sky. The New General Catalogue object NGC 31, a spiral galaxy in the constellation Phoenix
Galaxies can be described as all of the following: Astronomical object
The galaxy gets its name from the constellation Triangulum, where it can be spotted. It is sometimes informally referred to as the "Pinwheel Galaxy" by some astronomy references, in some computerized telescope software, and in some public outreach websites. However, the SIMBAD Astronomical Database, a professional database, collates formal designations for astronomical objects and indicates that Pinwheel Galaxy refers to Messier 101, which several amateur astronomy resources including public outreach websites identify by that name, and that is within the bounds of Ursa Major.
|
What are the most common seedless vascular plants?
|
[
"trees",
"grasses",
"weeds",
"ferns"
] |
D
|
Ferns are the most common seedless vascular plants ( Figure below ). They usually have large divided leaves called fronds. In most ferns, fronds develop from a curled-up formation called a fiddlehead ( Figure below ). The fiddlehead looks like the curled decoration on the end of a stringed instrument, such as a fiddle. Leaves unroll as the fiddleheads grow and expand. Ferns grow in a variety of habitats, ranging in size from tiny aquatic species to giant tropical plants.
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).
Dicot angiosperms dominate, with lesser amounts of ferns, palms, and herbaceous lycopods. Conifers are rare. Common plants include "Ficus" planicostata, "Myrica" torreyi, Sabalites sp., Platanites marginata, and Marmarthia pearsonii.
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.
Following the evolution of the seed habit, seed plants diversified, giving rise to a number of now-extinct groups, including seed ferns, as well as the modern gymnosperms and angiosperms. Gymnosperms produce "naked seeds" not fully enclosed in an ovary; modern representatives include conifers, cycads, Ginkgo, and Gnetales. Angiosperms produce seeds enclosed in a structure such as a carpel or an ovary. Ongoing research on the molecular phylogenetics of living plants appears to show that the angiosperms are a sister clade to the gymnosperms.
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.
|
In a monogamous pairing, a male individual is generally paired with what other type of individual in a sexual relationship?
|
[
"worker",
"male",
"drone",
"female"
] |
D
|
Visit this website (http://openstaxcollege. org/l/sex_selection) for informative videos on sexual selection. In monogamous systems, one male and one female are paired for at least one breeding season. In some animals, such as the gray wolf, these associations can last much longer, even a lifetime. Several explanations have been proposed for this type of.
Serial monogamy is a mating practice in which individuals may engage in sequential monogamous pairings, or in terms of humans, when men or women can marry another partner but only after ceasing to be married to the previous partner.Serial monogamy may effectively resemble polygyny in its reproductive consequences because both men and women are able to utilize both sexes reproductive lifespan through repeated marriages.Serial monogamy may also refer to sequential sexual relationships, irrespective of marital status. A pair of humans may remain sexually exclusive, or monogamous, until the relationship has ended and then each may go on to form a new exclusive pairing with a different partner. This pattern of serial monogamy is common among people in Western cultures.
marital monogamy refers to marriages of only two people, within the context of the institution of marriage.For instance, biologists, biological anthropologists, and behavioral ecologists often use monogamy in the sense of sexual, if not genetic (reproductive), exclusivity. When cultural or social anthropologists and other social scientists use the term monogamy, the meaning is social or marital monogamy.Marital monogamy may be further distinguished between: classical monogamy, "a single relationship between people who marry as virgins, remain sexually exclusive their entire lives, and become celibate upon the death of the partner" serial monogamy, marriage with only one other person at a time, in contrast to bigamy or polygamyDefining monogamy across cultures can be difficult because of different cultural assumptions. Some societies believe that monogamy requires limiting sexual activity to a single partner for life.
Mutual monogamy is a form of monogamy that exists when two partners agree to be sexually active with only one another. Being in a long-term mutually monogamous relationship reduces the risk of acquiring a sexually transmitted infection (STI). It is one of the most reliable ways to avoid STIs. Those who choose mutual monogamy can be tested before the sexual relationship to be certain they are not infected.
Monogamy exists in many societies around the world, resulting in extensive scientific research which tries to understand how these marriage systems might have evolved. In any species, there are three main aspects that combine to promote a monogamous mating system: paternal care, resource access, and mate choice; however, in humans, the main theoretical sources of monogamy are paternal care and extreme ecological stresses. Paternal care should be particularly important in humans due to the extra nutritional requirement of having larger brains and the lengthier developmental period. Therefore, the evolution of monogamy could be a reflection of this increased need for bi-parental care.
In these cases, the male has a greater chance to increase his own fitness by seeing that his offspring live long enough to reproduce. If the male is not present in these populations, the survivorship of the offspring is drastically lowered and there is a lowering in male fitness. Without monogamy, bi-parental care is less common and there is an increased chance of infanticide. Infanticide with monogamous pairing would lead to a lowered fitness for socially monogamous males and is not seen to a wide extent.
|
What is a mass spectrometer used to measure?
|
[
"partial atomic masses",
"relative atomic masses",
"subatomic masses",
"optical atomic masses"
] |
B
|
Although the masses of the electron, the proton, and the neutron are known to a high degree of precision (Table 1.3 "Properties of Subatomic Particles*"), the mass of any given atom is not simply the sum of the masses of its electrons, protons, and neutrons. For example, the ratio of the masses of 1H (hydrogen) and 2H (deuterium) is actually 0.500384, rather than 0.49979 as predicted from the numbers of neutrons and protons present. Although the difference in mass is small, it is extremely important because it is the source of the huge amounts of energy released in nuclear reactions (Chapter 20 "Nuclear Chemistry"). Because atoms are much too small to measure individually and do not have a charge, there is no convenient way to accurately measure absolute atomic masses. Scientists can measure relative atomic masses very accurately, however, using an instrument called a mass spectrometer. The technique is conceptually similar to the one Thomson used to determine the mass-to-charge ratio of the electron. First, electrons are removed from or added to atoms or molecules, thus producing charged particles called ions. When an electric field is applied, the ions are accelerated into a separate chamber where they are deflected from their initial trajectory by a magnetic field, like the electrons in Thomson’s experiment. The extent of the deflection depends on the mass-to-charge ratio of the ion. By measuring the relative deflection of ions that have the same charge, scientists can determine their relative masses (Figure 1.25 "Determining Relative Atomic Masses Using a Mass Spectrometer"). Thus it is not possible to calculate absolute atomic masses accurately by simply adding together the masses of the electrons, the protons, and the neutrons, and absolute atomic masses cannot be measured, but relative masses can be measured very accurately. It is actually rather common in chemistry to encounter a quantity whose magnitude can be measured only relative to some other quantity, rather than absolutely. We will encounter many other examples later in this text. In such cases,.
The mass recorded by a mass spectrometer can refer to different physical quantities depending on the characteristics of the instrument and the manner in which the mass spectrum is displayed.
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a mass spectrum, a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio.
An important enhancement to the mass resolving and mass determining capabilities of mass spectrometry is using it in tandem with chromatographic and other separation techniques.
Usually an oscilloscope records the arrival time of the ions. The mass is calculated from the measured time of flight.
In case of measuring the hydration rim using the depth profiling ability of the secondary ion mass spectrometry technique, the sample is mounted on a holder without any preparation or cutting. This method of measurement is non-destructive. There are two general SIMS modes: static mode and dynamic mode, depending on the primary ion current density, and three different types of mass spectrometers: magnetic sector, quadrupole and time-of-flight (TOF). Any mass-spectrometer can work in static mode (very low ion current, a top mono-atomic layer analysis), and dynamic mode (a high ion current density, in-depth analysis).
|
What combines sets of genes from two different parents leading to genetically diverse offspring?
|
[
"subject reproduction",
"cellular reproduction",
"sexual reproduction",
"sexual destruction"
] |
C
|
Gene families, part of a hierarchy of information storage in a genome, play a large role in the evolution and diversity of multicellular organisms. Gene families are large units of information and genetic variability. Over evolutionary time, gene families have expanded and contracted with new gene families being formed and some gene families being lost. In several evolutionary lineages, genes are gained and lost at relatively same rates.
Some multigene families are extremely homogenous, with individual genes members sharing identical or almost identical sequences. The process by which gene families maintain high homogeneity is Concerted evolution. Concerted evolution occurs through repeated cycles of unequal crossing over events and repeated cycles of gene transfer and conversion. Unequal crossing over leads to the expansion and contraction of gene families.
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.
Researchers often use the history of redundant genes in the form of gene families to learn about the phylogeny of a species. It takes time for redundant genes to undergo functional diversification; the degree of diversification between orthologs tells us how closely related the two genomes are. Gene duplication events can also be detected by looking at increases in gene duplicates.
In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridization, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo.
|
Global warming will raise ocean levels due to melt water from glaciers and the greater volume of what?
|
[
"greenhouse gases",
"rainforests",
"warmer water",
"rain"
] |
C
|
Range shifts are already being observed: for example, some European bird species ranges have moved 91 km northward. The same study suggested that the optimal shift based on warming trends was double that distance, suggesting that the populations are not moving quickly enough. Range shifts have also been observed in plants, butterflies, other insects, freshwater fishes, reptiles, and mammals. Climate gradients will also move up mountains, eventually crowding species higher in altitude and eliminating the habitat for those species adapted to the highest elevations. Some climates will completely disappear. The rate of warming appears to be accelerated in the arctic, which is recognized as a serious threat to polar bear populations that require sea ice to hunt seals during the winter months: seals are the only source of protein available to polar bears. A trend to decreasing sea ice coverage has occurred since observations began in the mid-twentieth century. The rate of decline observed in recent years is far greater than previously predicted by climate models. Finally, global warming will raise ocean levels due to melt water from glaciers and the greater volume of warmer water. Shorelines will be inundated, reducing island size, which will have an effect on some species, and a number of islands will disappear entirely. Additionally, the gradual melting and subsequent refreezing of the poles, glaciers, and higher elevation.
The Thwaites Glacier alone, in Western Antarctica is "currently responsible for approximately 4 percent of global sea level rise. It holds enough ice to raise the world ocean a little over 2 feet (65 centimeters) and backstops neighboring glaciers that would raise sea levels an additional 8 feet (2.4 meters) if all the ice were lost." The fact that the IPCC estimates did not include rapid ice sheet decay into their sea level predictions makes it difficult to ascertain a plausible estimate for sea level rise but a 2008 study found that the minimum sea level rise will be around 0.8 metres (2.6 ft) by 2100.
Each year about 8 mm (0.3 inches) of water from the entire surface of the oceans falls onto the Antarctica and Greenland ice sheets as snowfall. Slightly more water returns to the ocean in icebergs, from ice melting at the edges, and from rivers of meltwater flowing from ice sheets to the sea. The change in the total mass of ice on land, called the mass balance, is important because it causes changes in global sea level. High-precision gravimetry from satellites in low-noise flight has determined that in 2006, the Greenland and Antarctic ice sheets experienced a combined mass loss of 475 ± 158 Gt/yr, equivalent to 1.3 ± 0.4 mm/yr sea level rise.
Anthropogenic climate change is likely to cause significant changes in subglacial stream systems. As glacial melting increases as a result of rising global temperatures, water flux into and discharge from subglacial streams increases as well. Greater water input from surface melting may affect the hydrology of subglacial systems, changing the timing of seasonal variations. As a result of climate change-induced increases in meltwater, greater volumes of water are likely to reach the bed earlier in the year.
Conversely, the high stability of ice cover in Antarctica, where the thickness of the East Antarctic ice sheet allows it to rise nearly 4 km above the sea level, means that this continent has not experienced any net warming over the past seven decades: ice loss in the Antarctic and its contribution to sea level rise is instead driven entirely by the warming of the Southern Ocean, which had absorbed 35–43% of the total heat taken up by all oceans between 1970 and 2017.Ice–albedo feedback also has a smaller, but still notable effect on the global temperatures. Arctic ice decline between 1979 and 2011 is estimated to have been responsible for 0.21 watts per square meter (W/m2) of radiative forcing, which is equivalent to a quarter of radiative forcing from CO2 increases over the same period. When compared to cumulative increases in greenhouse gas radiative forcing since the start of the Industrial Revolution, it is equivalent to the estimated 2019 radiative forcing from nitrous oxide (0.21 W/m2), nearly half of 2019 radiative forcing from methane (0.54 W/m2) and 10% of the cumulative CO2 increase (2.16 W/m2).
For RCP8.5 the sea level would rise between 52 and 98 cm (20+1⁄2 and 38+1⁄2 in). The report did not estimate the possibility of global SLR being accelerated by the outright collapse of the marine-based parts of the Antarctic ice sheet, due to the lack of reliable information, only stating with medium confidence that if such a collapse occurred, it would not add more than several tens of centimeters to 21st century sea level rise. Since its publication, multiple papers have questioned this decision and presented higher estimates of SLR after attempting to better incorporate ice sheet processes in Antarctica and Greenland and to compare the current events with the paleoclimate data.
|
What are groups of young stars loosely held together by gravity called?
|
[
"constellations",
"galaxies",
"open clusters",
"closed clusters"
] |
C
|
Open clusters are groups of young stars loosely held together by gravity.
Stars form when the mass gas in part of a cloud becomes too great, causing it to collapse due to the Jeans instability. Most stars do not form alone, but in groups containing hundreds or thousands of other stars. RCW 36 is an example of this type of "clustered" star formation.
In astronomy, dynamical mass segregation is the process by which heavier members of a gravitationally bound system, such as a star cluster, tend to move toward the center, while lighter members tend to move farther away from the center.
Close interactions and near-collisions of stars occur relatively often in globular clusters because of their high star density. These chance encounters give rise to some exotic classes of stars – such as blue stragglers, millisecond pulsars, and low-mass X-ray binaries – which are much more common in globular clusters. How blue stragglers form remains unclear, but most models attribute them to interactions between stars, such as stellar mergers, the transfer of material from one star to another, or even an encounter between two binary systems. The resulting star has a higher temperature than other stars in the cluster with comparable luminosity and thus differs from the main-sequence stars formed early in the cluster's existence.
Stars form when clumps of hydrogen and other gases in an H II region contract under their own gravity. As the gas collapses, the central clump grows stronger and the gas heats to extreme temperatures by converting gravitational potential energy to thermal energy. If the temperature gets high enough, nuclear fusion will ignite and form a protostar.
The fragmentation of the cloud into multiple stars distributes some of that angular momentum. The primordial binaries transfer some angular momentum by gravitational interactions during close encounters with other stars in young stellar clusters. These interactions tend to split apart more widely separated (soft) binaries while causing hard binaries to become more tightly bound. This produces the separation of binaries into their two observed populations distributions.
|
What does a pollinator pick up from its body and carry directly to another plant of the same species?
|
[
"pollen",
"spore",
"pathogen",
"seed"
] |
A
|
Wind-blown pollen might land anywhere and be wasted. Another adaptation solved this problem. Plants evolved traits that attract specific animal pollinators. Like the bee in Figure below , a pollinator picks up pollen on its body and carries it directly to another plant of the same species. This greatly increases the chance that fertilization will occur.
Some pollinators include insects, birds, bats, and wind. In some petals, a distinction can be made between a lower narrowed, stalk-like basal part referred to as the claw, and a wider distal part referred to as the blade (or limb). Often the claw and blade are at an angle with one another.
Selection might actually favor some degree of generalization while some flowers can also retain particular traits that allow them to adapt to a certain type of pollinator, but will ultimately be molded by the pollinators that are the most effective and visit the most frequently. This leads to shifts in pollination syndromes and to some genera having a high diversity of pollination syndromes among species, suggesting that pollinators are a primary selective force driving diversity and speciation. Pollinator-mediated selection requires isolation and therefore cannot function in sympatry. Floral isolation is a consequence of pollinator behavior that reduces inter-lineage pollen transfer, which reduces gene flow and increases the possibility for a transition to different syndromes. Isolation with no gene flow between populations allows for the development of distinct species, thus speciation is a result of reproductive isolation and can be driven by pollinator-mediated selection.
A pollinator garden is a type of garden designed with the intent of growing specific nectar and pollen-producing plants, in a way that attracts pollinating insects known as pollinators. Pollinators aid in the production of one out of every three bites of food consumed by humans, and pollinator gardens are a way to offer support for these species. In order for a garden to be considered a pollinator garden, it should provide various nectar producing flowers, shelter or shelter-providing plants for pollinators, and avoid the use of pesticides.
Chiropterophily or bat pollination is the pollination of flowering plants by bats. Plants adapted to use bats or moths as pollinators typically have white petals, strong scent and flower at night, whereas plants that use birds as pollinators tend to produce copious nectar and have red petals.
The stigma extends beyond the anthers, making self-pollination difficult, so insects must cross-pollinate for the plants to produce seed.Pollinated flowers develop into an oval pod with three chambers, 6 mm (1⁄2 in) long, which is enclosed by the green calyx. The plant spreads by reseeding itself. The Latin specific epithet reptans means creeping.
|
What is formed when an oxygen atom picks up a pair of hydrogen ions from a solution?
|
[
"water",
"liquid",
"turpentine",
"ammonia"
] |
A
|
This excited state then decomposes to species such as hydroxyl radicals (HO. ), hydrogen atoms (H.) and oxygen atoms (O.).
In the hexagonal or cubic ice phase the oxygen ions form a tetrahedral structure with an O–O bond length 2.76 Å (276 pm), while the O–H bond length measures only 0.96 Å (96 pm). Every oxygen (white) ion is surrounded by four hydrogen ions (black) and each hydrogen ion is surrounded by 2 oxygen ions, as shown in Figure 5. Maintaining the internal H2O molecule structure, the minimum energy position of a proton is not half-way between two adjacent oxygen ions.
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).
Two other well-known structures are the Zundel cation and the Eigen cation. The Eigen solvation structure has the hydronium ion at the center of an H9O+4 complex in which the hydronium is strongly hydrogen-bonded to three neighbouring water molecules. In the Zundel H5O+2 complex the proton is shared equally by two water molecules in a symmetric hydrogen bond.
Iodine monoxide can be obtained by the reaction between iodine and oxygen: I2 + O2 → 2 IO
|
What does the driving of turbines by the heating of water to steam accomplish?
|
[
"depletion of electricity",
"generation of electricity",
"diffusion of electricity",
"absorption of electricity"
] |
B
|
Nuclear reactors heat water to steam to drive a turbine for generation of electricity.
A boiling water reactor uses demineralized water as a coolant and neutron moderator. Heat is produced by nuclear fission in the reactor core, and this causes the cooling water to boil, producing steam. The steam is directly used to drive a turbine, after which it is cooled in a condenser and converted back to liquid water. This water is then returned to the reactor core, completing the loop.
Steam turbines could be built to operate on higher pressure and temperature steam. A fundamental principle of thermodynamics is that the higher the temperature of the steam entering an engine, the higher the efficiency. The introduction of steam turbines motivated a series of improvements in temperatures and pressures. The resulting increased conversion efficiency lowered electricity prices.The power density of boilers was increased by using forced combustion air and by using compressed air to feed pulverized coal. Also, coal handling was mechanized and automated.
Inside the tubes the cooling water runs in a parallel way, while steam moves in a vertical downward position from the wide opening at the top and travel through the tube. Furthermore, boilers are categorized as initial application of heat exchangers. The word steam generator was regularly used to describe a boiler unit where a hot liquid stream is the source of heat rather than the combustion products. Depending on the dimensions and configurations the boilers are manufactured. Several boilers are only able to produce hot fluid while on the other hand the others are manufactured for steam production.
In the reaction turbine, the rotor blades themselves are arranged to form convergent nozzles. This type of turbine makes use of the reaction force produced as the steam accelerates through the nozzles formed by the rotor. Steam is directed onto the rotor by the fixed vanes of the stator. It leaves the stator as a jet that fills the entire circumference of the rotor. The steam then changes direction and increases its speed relative to the speed of the blades. A pressure drop occurs across both the stator and the rotor, with steam accelerating through the stator and decelerating through the rotor, with no net change in steam velocity across the stage but with a decrease in both pressure and temperature, reflecting the work performed in the driving of the rotor.
Compared to other methods of heating, it is more difficult to control the output of a steam system. However, steam can be sent, for example, between buildings on a campus to allow use of an efficient central boiler and low cost fuel. Tall buildings take advantage of the low density of steam to avoid the excessive pressure required to circulate hot water from a basement-mounted boiler. In industrial systems, process steam used for power generation or other purposes can also be tapped for space heating. Steam for heating systems may also be obtained from heat recovery boilers using otherwise wasted heat from industrial processes.
|
What is a device that changes kinetic energy to electrical energy through electromagnetic induction?
|
[
"a battery",
"a windmill",
"an electric generator",
"a diesel engine"
] |
C
|
An electric generator is a device that changes kinetic energy to electrical energy through electromagnetic induction. A simple diagram of an electric generator is shown in Figure below . In a generator, some form of energy is applied to turn a shaft. This causes a coil of wire to rotate between opposite poles of a magnet. Because the coil is rotating in a magnetic field, electric current is generated in the wire. If the diagram in Figure below looks familiar to you, that’s because a generator is an electric motor in reverse. Look back at the electric motor in Figure above . If you were to mechanically turn the shaft of the motor (instead of using electromagnetism to turn it), the motor would generate electricity just like an electric generator. You can learn how to make a very simple electric generator by watching the video at the URL below. Making your own generator will help you understand how a generator works.
The appliance can then produce light, typically from a light-emitting diode, until the capacitor is discharged. It can then be re-charged by further shaking. Because of this, they are sometimes referred to as a faraday flashlight. Other devices that use linear alternators to generate electricity include the free-piston linear generator, an internal combustion engine, and the free-piston Stirling engine, an external combustion engine.
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.
An inductor is an electronic component that stores energy in a magnetic field inside a coil of wire. A current-carrying coil of wire induces a magnetic field according to Ampère's circuital law. The greater the current I, the greater the energy stored in the magnetic field and the lower the inductance which is defined L = Φ B / I {\textstyle L=\Phi _{B}/I} where Φ B {\textstyle \Phi _{B}} is the magnetic flux produced by the coil of wire. The inductance is a measure of the circuit's resistance to a change in current and so inductors with high inductances can also be used to oppose alternating current.
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.
Spacecraft electric propulsion (or just electric propulsion) is a type of spacecraft propulsion technique that uses electrostatic or electromagnetic fields to accelerate mass to high speed and thus generate thrust to modify the velocity of a spacecraft in orbit. The propulsion system is controlled by power electronics. Electric thrusters typically use much less propellant than chemical rockets because they have a higher exhaust speed (operate at a higher specific impulse) than chemical rockets. Due to limited electric power the thrust is much weaker compared to chemical rockets, but electric propulsion can provide thrust for a longer time.Electric propulsion was first successfully demonstrated by NASA and is now a mature and widely used technology on spacecraft.
|
How many naturally occurring elements are known on earth?
|
[
"85",
"90",
"60",
"87"
] |
B
|
An element, as defined in Chapter 1 "Chemistry, Matter, and Measurement", is a substance that cannot be broken down into simpler chemical substances. There are about 90 naturally occurring elements known on Earth. Using technology, scientists have been able to create nearly 30 additional elements that do not occur in nature. Today, chemistry recognizes 118 elements—some of which were created an atom at a time. Figure 2.1 "Samples of Elements" shows some of the chemical elements.
The set of elements usually considered as TCEs vary depending on the source, but they usually include: Seventeen rare-earth elements The six platinum-group elements Twelve assorted elements
The remaining elements are called "trace elements". They are iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, and selenium.Four elements comprise 96% of the human body by weight: carbon, hydrogen, oxygen, and nitrogen) (CHON). These elements are usually not included in lists of nutrient minerals.
Caesium (55Cs) has 40 known isotopes, making it, along with barium and mercury, one of the elements with the most isotopes. The atomic masses of these isotopes range from 112 to 151. Only one isotope, 133Cs, is stable.
Rhenium is one of the rarest elements in Earth's crust with an average concentration of 1 ppb; other sources quote the number of 0.5 ppb making it the 77th most abundant element in Earth's crust. Rhenium is probably not found free in nature (its possible natural occurrence is uncertain), but occurs in amounts up to 0.2% in the mineral molybdenite (which is primarily molybdenum disulfide), the major commercial source, although single molybdenite samples with up to 1.88% have been found. Chile has the world's largest rhenium reserves, part of the copper ore deposits, and was the leading producer as of 2005.
The elements 57 (La) to 71 (Lu) are very similar chemically to one another and frequently occur together in nature, often anywhere from three to all 15 of the lanthanides (along with yttrium as a 16th) occur in minerals such as samarskite, monazite and many others which can also contain the other two group 3 elements as well as thorium and occasionally other actinides as well. A majority of the rare earths were discovered at the same mine in Ytterby, Sweden and four of them are named (yttrium, ytterbium, erbium, terbium) after the village and a fifth (holmium) after Stockholm; scandium is named after Scandinavia, thulium after the old name Thule, and the immediately-following group 4 element (number 72) hafnium is named for the Latin name of the city of Copenhagen.Samarskite (a mineral which is the source of the name of the element samarium) and other similar minerals in particular also have these elements in association with the nearby metals tantalum, niobium, hafnium, zirconium, vanadium, and titanium, from group 4 and group 5 often in similar oxidation states. Monazite is a phosphate of numerous group 3 + lanthanide + actinide metals and mined especially for the thorium content and specific rare earths especially lanthanum, yttrium and cerium.
|
What are the two types of vesicle transport called?
|
[
"endocytosis and exocytosis",
"dielectric and exocytosis",
"epithelium and exocytosis",
"eptocytosis and exocytosis"
] |
A
|
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.
Which cargo molecules are incorporated into a particular type of vesicle relies on specific interactions. Some of these interactions are directly with AP complexes and some are indirectly with "alternative adaptors", as shown in this diagram. As examples, membrane proteins can have direct interactions, while proteins that are soluble in the lumen of the donor organelle bind indirectly to AP complexes by binding to membrane proteins that traverse the membrane and bind at their lumenal end to the desired cargo molecule. Molecules that should not be included in the vesicle appear to be excluded by "molecular crowding".The "signals" or amino acid "motifs" in the cargo proteins that interact with the adaptor proteins can be very short.
Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses ATP, and secondary active transport that uses an electrochemical gradient. An example of active transport in human physiology is the uptake of glucose in the intestines.
Although there is no continuous membrane between the endoplasmic reticulum and the Golgi apparatus, membrane-bound transport vesicles shuttle proteins between these two compartments. Vesicles are surrounded by coating proteins called COPI and COPII. COPII targets vesicles to the Golgi apparatus and COPI marks them to be brought back to the rough endoplasmic reticulum.
Soluble proteins can reach the surface of the cell both by non-vesicular and vesicular mechanisms. Non-vesicular mechanisms use a carrier to get proteins into extracellular space (for example phosphatidylinositol-4,5-bisphosphate). Vesicular mechanisms can use the lysosome-dependent pathway, microvesicle shedding or biogenesis of multivesicular bodies. == References ==
|
What do you call a species that has died out in the past?
|
[
"endangered",
"inhabit",
"remnant",
"extinct"
] |
D
|
Life is complex, and there are millions of species alive today. Many millions more lived in the past and then went extinct. Organisms include microscopic, single-celled organisms. They also include complex, multicellular animals such as you. Clearly, life science is a huge science. That’s why a life scientist usually specializes in just one field within life science. Dr. Smith, for example, specializes in ecology. You can see the focus of ecology and several other life science fields in Table below . Click on the links provided if you want to learn about careers in these fields.
Death plays a role in extinction, the cessation of existence of a species or group of taxa, reducing biodiversity, due to extinction being generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point). Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively.
Their taxonomy may never be fully elucidated, and so their postulated status as a separate species is hypothetical. It is presumed to have gone extinct in the late 18th century, if it did indeed exist. == References ==
An attempt to study them in 1988 yielded only one animal, which had already been killed by a hunter. The specimen that lived at the Toronto Zoo has since died. This rarity also limited what is understood about the Liberian mongoose's interaction with other aspects of the ecosystem.
There are also a number of extinct species identified from fossil evidence:
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.
|
Where does the embryo develop in a plant?
|
[
"inside the female plant after fertilization",
"outside the female plant after fertilization",
"inside the stem after fertilization",
"inside the male plant after fertilization"
] |
A
|
In plants, the embryo develops inside of the female plant after fertilization. Algae do not keep the embryo inside of themselves but release it into water. This was the first feature to evolve that separated plants from green algae. This is also the only adaptation shared by all plants.
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).
Plant regeneration via somatic embryogenesis occurs in five steps: initiation of embryogenic cultures, proliferation of embryogenic cultures, prematuration of somatic embryos, maturation of somatic embryos and plant development on nonspecific media. Initiation and proliferation occur on a medium rich in auxin, which induces differentiation of localized meristematic cells. The auxin typically used is 2,4-D. Once transferred to a medium with low or no auxin, these cells can then develop into mature embryos. Germination of the somatic embryo can only occur when it is mature enough to have functional root and shoot apices
There are a few ways that reproduction occurs within plant life, and one way is through parthenogenesis. Parthenogenesis is defined as "a form of asexual reproduction in which genetically identical offspring (clones) are produced". Another form of reproduction is through cross-fertilization, which is defined as "fertilization in which the egg and sperm are produced by different individuals", and in plants this occurs in the ovule.
Somatic embryogenesis is an artificial process in which a plant or embryo is derived from a single somatic cell. Somatic embryos are formed from plant cells that are not normally involved in the development of embryos, i.e. ordinary plant tissue. No endosperm or seed coat is formed around a somatic embryo. Cells derived from competent source tissue are cultured to form an undifferentiated mass of cells called a callus.
The sporophyte develops from the zygote produced when a haploid egg cell is fertilized by a haploid sperm and each sporophyte cell therefore has a double set of chromosomes, one set from each parent. All land plants, and most multicellular algae, have life cycles in which a multicellular diploid sporophyte phase alternates with a multicellular haploid gametophyte phase. In the seed plants, the largest groups of which are the gymnosperms and flowering plants (angiosperms), the sporophyte phase is more prominent than the gametophyte, and is the familiar green plant with its roots, stem, leaves and cones or flowers. In flowering plants the gametophytes are very reduced in size, and are represented by the germinated pollen and the embryo sac.
|
What is the method of setting or correcting a measuring device by matching it to known measurement standards called?
|
[
"calibration",
"parallax",
"distortion",
"precision"
] |
A
|
When using measuring devices, we often use a technique called calibration to increase the accuracy of our measurements. Calibration is a method of setting or correcting a measuring device by matching it to known measurement standards. To better understand calibration, we will look at the example of calibrating a thermometer. All thermometers are slightly different in their temperature readings. One way to calibrate a thermometer is by using the freezing point and boiling point of water ( Figure below ). If we know that water freezes at 0°C and boils at 100°C, we can calibrate our thermometer by measuring the temperature of ice water and of boiling water. We place the thermometer in ice water and wait for the thermometer liquid to reach a stable height, then place a mark at this height which represents 0°C. Then we place the thermometer in boiling water, and after waiting for the thermometer liquid to reach a stable height, we place a mark at this height which represents 100°C. We can then place 100 equally spaced divisions between our 0 and 100°C marks to each represent 1°C. Our thermometer has now been calibrated using the known values for the freezing point and boiling point of water, and can be used to measure temperatures of objects between 0 and 100°C.
In metrology (the science of measurement), a standard (or etalon) is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the fundamental reference for a system of weights and measures, against which all other measuring devices are compared. Historical standards for length, volume, and mass were defined by many different authorities, which resulted in confusion and inaccuracy of measurements. Modern measurements are defined in relationship to internationally standardized reference objects, which are used under carefully controlled laboratory conditions to define the units of length, mass, electrical potential, and other physical quantities.
The process will determine the measurement value and uncertainty of the device that is being calibrated and create a traceability link to the measurement standard. The four primary reasons for calibrations are to provide traceability, to ensure that the instrument (or standard) is consistent with other measurements, to determine accuracy, and to establish reliability. Traceability works as a pyramid, at the top level there is the international standards, at the next level national metrology institutes calibrate the primary standards through realisation of the units creating the traceability link from the primary standard and the unit definition. Through subsequent calibrations between national metrology institutes, calibration laboratories, and industry and testing laboratories the realisation of the unit definition is propagated down through the pyramid. The traceability chain works upwards from the bottom of the pyramid, where measurements done by industry and testing laboratories can be directly related to the unit definition at the top through the traceability chain created by calibration.
Electrical Metrology: Allowing for more precise readings and measurements of current, voltage, power, and attenuation ratio, this will allow for more precise control over maintaining legal levels which provides a specific need and use for the technology. Galvanometers: a range of measurement devices that will be of use to the scientific field though more precise measurements in specialized fields. == References ==
These vary internationally, e.g., NIST 150-2G in the U.S. and NABL-141 in India. Together, these standards cover instruments that measure various physical quantities such as electromagnetic radiation (RF probes), sound (sound level meter or noise dosimeter), time and frequency (intervalometer), ionizing radiation (Geiger counter), light (light meter), mechanical quantities (limit switch, pressure gauge, pressure switch), and, thermodynamic or thermal properties (thermometer, temperature controller). The standard instrument for each test device varies accordingly, e.g., a dead weight tester for pressure gauge calibration and a dry block temperature tester for temperature gauge calibration.
All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty. These instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators. Virtual instrumentation is widely used in the development of modern measuring instruments.
|
What property of warm air causes it to rise above cold air?
|
[
"greater pressure",
"lower density",
"greater density",
"higher temperature"
] |
B
|
The warm-air vent is placed near the floor of the room. Warm air is less dense than cold air so it rises. If the warm-air vent were placed near the ceiling instead, how would this affect the transfer of thermal energy throughout the room?.
The air can rise due to convection, large-scale atmospheric motions, or a physical barrier such as a mountain (orographic lift). Conductive cooling occurs when the air comes into contact with a colder surface, usually by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation, either by the air or by the surface underneath.
Surface temperature differences in turn cause pressure differences. A hot surface warms the air above it causing it to expand and lower the density and the resulting surface air pressure. The resulting horizontal pressure gradient moves the air from higher to lower pressure regions, creating a wind, and the Earth's rotation then causes deflection of this airflow due to the Coriolis effect.
Water vapor in saturated air is normally attracted to condensation nuclei such as salt particles that are small enough to be held aloft by normal circulation of the air. If the condensation process occurs below the freezing level in the troposphere, the nuclei help transform the vapor into very small water droplets. Clouds that form just above the freezing level are composed mostly of supercooled liquid droplets, while those that condense out at higher altitudes where the air is much colder generally take the form of ice crystals. An absence of sufficient condensation particles at and above the condensation level causes the rising air to become supersaturated and the formation of cloud tends to be inhibited.
The beginning of a heat burst is the time during which the air temperature increases without decreasing until after the peak; the end of a heat burst is when the system ceases to affect the temperature and dew point of the area. In addition to researching the life cycle and characteristics of heat bursts, a group of scientists concluded that the topography of Oklahoma coincided with the change in atmospheric moisture between northwest and southeast Oklahoma. An increase in convection normally occurs over the High Plains of the United States during the late spring and summer. They also concluded that a higher increase in convection develops if a mid-tropospheric lifting mechanism interacts with an elevated moist layer.
The relatively warmer water leads to upward convection, causing a low to form, and precipitation usually in the form of snow. Tropical cyclones and winter storms are intense varieties of low pressure. Over land, thermal lows are indicative of hot weather during the summer.
|
Which branch of biology studies animal behavior?
|
[
"ethology",
"microbiology",
"anthropology",
"embryology"
] |
A
|
The branch of biology that studies animal behavior is called ethology. Ethologists usually study how animals behave in their natural environment. They try to determine the cause of behaviors, how behaviors develop, and how and why behaviors evolve.
animal behaviour See ethology. animal communication animal migration applied ecology A branch of ecology which uses ecological principles and insights to solve environment-related problems. It includes agroecology and conservation biology.
Behavioral neuroscience, also known as biological psychology, biopsychology, or psychobiology, is the application of the principles of biology to the study of physiological, genetic, and developmental mechanisms of behavior in humans and other animals.
Comparative psychology also studies animal behavior, but, as opposed to ethology, is construed as a sub-topic of psychology rather than as one of biology. Historically, where comparative psychology has included research on animal behavior in the context of what is known about human psychology, ethology involves research on animal behavior in the context of what is known about animal anatomy, physiology, neurobiology, and phylogenetic history. Furthermore, early comparative psychologists concentrated on the study of learning and tended to research behavior in artificial situations, whereas early ethologists concentrated on behavior in natural situations, tending to describe it as instinctive. The two approaches are complementary rather than competitive, but they do result in different perspectives, and occasionally conflicts of opinion about matters of substance.
These applications include: Studying the diversity of organisms and the differentiation between extinct and living creatures. Biologists study the well-understood relationships by making many different diagrams and "trees" (cladograms, phylogenetic trees, phylogenies, etc.). Including the scientific names of organisms, species descriptions and overviews, taxonomic orders, and classifications of evolutionary and organism histories.
Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments.Biologists are able to study life at multiple levels of organization, from the molecular biology of a cell to the anatomy and physiology of plants and animals, and evolution of populations. Hence, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they use.
|
What unit of measure is equal to the amount of work a horse can do in 1 minute?
|
[
"horsepower",
"joule",
"watt",
"torque"
] |
A
|
Power may be measured in a unit called the horsepower. One horsepower is the amount of work a horse can do in 1 minute, which equals 745 watts of power.
Industrial engineers use a variety of rating scales, and one which has achieved wide use is the British Standards Rating Scale which is a scale where 0 corresponds to no activity and 100 corresponds to standard rating. Rating should be expressed as 'X' BS. Below is an illustration of the Standard Scale: Rating walking pace 0 no activity 50 very slow 75 steady 100 brisk (standard rating) 125 very fast 150 exceptionally fast The basic time for a task, or element, is the time for carrying out an element of work or an operation at standard rating. Basic time = observed time x observed rating The result is expressed in basic minutes – BMs. The work content of a job or operation is defined as: basic time + relaxation allowance + any allowance for additional work – e.g. that part of contingency allowance which represents work.
The task is performed by an average worker The worker's pace represents standard performance The worker uses the standard method The task is performed on a standard work unit
Scientific systems of units are a refinement of the concept of weights and measures historically developed for commercial purposes.Science, medicine, and engineering often use larger and smaller units of measurement than those used in everyday life. The judicious selection of the units of measurement can aid researchers in problem solving (see, for example, dimensional analysis). In the social sciences, there are no standard units of measurement and the theory and practice of measurement is studied in psychometrics and the theory of conjoint measurement.
Defining a unit for resistance that is coherent with units of energy and time in effect also requires defining units for potential and current. It is desirable that one unit of electrical potential will force one unit of electric current through one unit of electrical resistance, doing one unit of work in one unit of time, otherwise, all electrical calculations will require conversion factors. Since so-called "absolute" units of charge and current are expressed as combinations of units of mass, length, and time, dimensional analysis of the relations between potential, current, and resistance show that resistance is expressed in units of length per time – a velocity.
Since a typical horse pulled a bus for four or five hours per day, covering about a dozen miles, many systems needed ten or more horses in stable for each bus. With the advent of mass-produced steel (at around 1860), horse-buses were put on rails as the same horse could then move 3 to 10 times as many people. This was not only more efficient, but faster and produced, in an age of unpaved streets, a far superior ride.
|
What organism is characterized by an incomplete digestive system and a single, tentacled opening?
|
[
"annelids",
"prokaryotes",
"cnidarians",
"sponges"
] |
C
|
Cnidarians have an incomplete digestive system with a single opening. The opening is surrounded by tentacles, which are covered with nematocyst cells and used to capture prey. Digestion takes place in the digestive cavity. Nutrients are absorbed and gases are exchanged through the cells lining this cavity. Fluid in the cavity supports and stiffens the cnidarian body.
Single-celled organisms as well as sponges digest their food intracellularly. Other multi-cellular organisms digest their food extracellularly, within a digestive cavity. In this case the digestive enzymes are released into a cavity that is continuous with the animal's external environment. In cnidarians and in flatworms such as planarians, the digestive cavity, called a gastrovascular cavity, has only one opening that serves as both mouth and anus.
These have a more or less cylindrical body with a terminal mouth on a raised protuberance called the hypostome, surrounded by a number of tentacles. The polyp contains a central cavity, in which initial digestion takes place.
Partially digested food may then be passed into the hydrocaulus for distribution around the colony and completion of the digestion process. Unlike some other cnidarian groups, the lining of the central cavity lacks stinging nematocysts, which are found only on the tentacles and outer surface. All colonial hydrozoans also include some polyps specialized for reproduction.
It can be divided into three sections – the foregut, midgut and hindgut – each of which performs a different process of digestion. In addition to the alimentary canal, insects also have paired salivary glands and salivary reservoirs. These structures usually reside in the thorax, adjacent to the foregut. : 70–77
This starts at the mouth and ends at the anus, covering a distance of about nine metres.A major digestive organ is the stomach. Within its mucosa are millions of embedded gastric glands. Their secretions are vital to the functioning of the organ.
|
What term is not the same as energy, but means the energy per unit charge?
|
[
"voltage",
"frequency",
"speed",
"mass"
] |
A
|
The second equation is equivalent to the first. Voltage is not the same as energy. Voltage is the energy per unit charge. Thus a motorcycle battery and a car battery can both have the same voltage (more precisely, the same potential difference between battery terminals), yet one stores much more energy than the other since ΔPE = qΔV . The car battery can move more charge than the motorcycle battery, although both are 12 V batteries.
It can also be expressed as amperes times ohms (current times resistance, Ohm's law), webers per second (magnetic flux per time), watts per ampere (power per current), or joules per coulomb (energy per charge), which is also equivalent to electronvolts per elementary charge: V = A ⋅ Ω = Wb s = W A = J C = eV e . {\displaystyle {\text{V}}={\text{A}}{\cdot }\Omega ={\frac {\text{Wb}}{\text{s}}}={\frac {\text{W}}{\text{A}}}={\frac {\text{J}}{\text{C}}}={\frac {\text{eV}}{e}}.} The volt is named after Alessandro Volta. As with every SI unit named for a person, its symbol starts with an upper case letter (V), but when written in full it follows the rules for capitalisation of a common noun; i.e., "volt" becomes capitalised at the beginning of a sentence and in titles, but is otherwise in lower case.
Power (physics)In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second. In older works, power is sometimes called activity.
List of common units for energy. Official or common symbol in brackets after name and exact or approximate value of unit in joule in brackets after description.
Defining a unit for resistance that is coherent with units of energy and time in effect also requires defining units for potential and current. It is desirable that one unit of electrical potential will force one unit of electric current through one unit of electrical resistance, doing one unit of work in one unit of time, otherwise, all electrical calculations will require conversion factors. Since so-called "absolute" units of charge and current are expressed as combinations of units of mass, length, and time, dimensional analysis of the relations between potential, current, and resistance show that resistance is expressed in units of length per time – a velocity.
As a simple example, burning one kilogram of coal releases more energy than detonating a kilogram of TNT, but because the TNT reaction releases energy more quickly, it delivers more power than the coal. If ΔW is the amount of work performed during a period of time of duration Δt, the average power Pavg over that period is given by the formula It is the average amount of work done or energy converted per unit of time. Average power is often called "power" when the context makes it clear. Instantaneous power is the limiting value of the average power as the time interval Δt approaches zero. When power P is constant, the amount of work performed in time period t can be calculated as In the context of energy conversion, it is more customary to use the symbol E rather than W.
|
What specific part of the african violet is used to propagate other plants?
|
[
"petals",
"leaves",
"spores",
"roots"
] |
B
|
Red plants are used in white magic rituals, while green plants are used in black magic rituals. They are also commonly used in protection and warding rituals. Among the Baktaman people, red plants are used for initiation rites, while green plants are used for healing.
Many plants are fluorescent due to the presence of chlorophyll, which is probably the most widely-distributed fluorescent molecule, producing red emission under a range of excitation wavelengths. This attribute of chlorophyll is commonly used by ecologists to measure photosynthetic efficiency.The Mirabilis jalapa flower contains violet, fluorescent betacyanins and yellow, fluorescent betaxanthins. Under white light, parts of the flower containing only betaxanthins appear yellow, but in areas where both betaxanthins and betacyanins are present, the visible fluorescence of the flower is faded due to internal light-filtering mechanisms. Fluorescence was previously suggested to play a role in pollinator attraction, however, it was later found that the visual signal by fluorescence is negligible compared to the visual signal of light reflected by the flower.
Oca is usually propagated vegetatively by planting whole tubers. Propagation by seed is possible but is rarely used in practice. Sexual propagation is complicated by several factors.
The phloem and xylem are parallel to each other, but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch (ramify) to form veins which supply as much of the leaf as possible, ensuring that cells carrying out photosynthesis are close to the transportation system.Typically leaves are broad, flat and thin (dorsiventrally flattened), thereby maximising the surface area directly exposed to light and enabling the light to penetrate the tissues and reach the chloroplasts, thus promoting photosynthesis. They are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications.
The bacteria invade the plant through the water the plant absorbs and once inside spreads rapidly. It obtains its name because it will blacken and clog the veins of the plant making it impossible to keep nutrients moving through the plant. Copper is the primary treatment for black rot control.
|
What are fibers that depend on aerobic respiration called?
|
[
"hydrogen fibers",
"oxidative fibers",
"evaporative fibers",
"fragile fibers"
] |
B
|
Anaerobic cellular respiration and fermentation generate ATP in very different ways, and the terms should not be treated as synonyms. Cellular respiration (both aerobic and anaerobic) uses highly reduced chemical compounds such as NADH and FADH2 (for example produced during glycolysis and the citric acid cycle) to establish an electrochemical gradient (often a proton gradient) across a membrane. This results in an electrical potential or ion concentration difference across the membrane. The reduced chemical compounds are oxidized by a series of respiratory integral membrane proteins with sequentially increasing reduction potentials, with the final electron acceptor being oxygen (in aerobic respiration) or another chemical substance (in anaerobic respiration).
Fast oxidative (type IIA) fibers have fast contractions and primarily use aerobic respiration, but because they may switch to anaerobic respiration (glycolysis), can fatigue more quickly than slow oxidative fibers. Fast glycolytic (type IIX)) fibers have fast contractions and primarily use anaerobic glycolysis. The FG fibers fatigue more quickly than the others. Most skeletal muscles in a human contain(s) all three types, although in varying proportions.
Infiltration, which enables some oxygen infiltration, allowing for limited microbial respiration. Available carbohydrates (CHOs) are lost as heat and gas. Emptying, which exposes surface, causing additional loss; rate of loss increases.
After oxygen, nitrate, manganeses, and iron are depleted, sulfate is the main electron acceptor used in anaerobic respiration. The metabolism associated with this is dissimilatory sulfate reduction (DSR) and is carried out by sulfur-reducing bacteria, which are widely distributed in anoxic environments. DSR oxidizes organic carbon using sulfate, and is described by the following equation: SO 4 2 − + 2 CH 2 O ⟶ H 2 S + 2 HCO 3 − {\displaystyle {\ce {SO4^2- +2CH2O -> H2S +2HCO3^-}}} .
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.
|
Which form of electromagnetic waves have more energy: low frequency wave or high frequency waves?
|
[
"neither",
"low frequency waves",
"the same",
"high frequency waves"
] |
D
|
The energy of electromagnetic waves depends on their frequency. Low-frequency waves have little energy and are normally harmless. High-frequency waves have a lot of energy and are potentially very harmful.
Microwave diathermy uses microwaves, radio waves which are higher in frequency and shorter in wavelength than the short waves above. Microwaves, which are also used in radar, have a frequency above 300 MHz and a wavelength less than one meter. Most, if not all, of the therapeutic effects of microwave therapy are related to the conversion of energy into heat and its distribution throughout the body tissues. This mode of diathermy is considered to be the easiest to use, but the microwaves have a relatively poor depth of penetration.
There are three types of mechanical waves: transverse waves, longitudinal waves, and surface waves. Some of the most common examples of mechanical waves are water waves, sound waves, and seismic waves. Like all waves, mechanical waves transport energy.
Wave and Tidal Energy. Wiley & Sons. DOI: 10.1002/9781119014492.ch13
Electromagnetic waves were analysed theoretically by James Clerk Maxwell in 1864. Maxwell developed a set of equations that could unambiguously describe the interrelationship between electric field, magnetic field, electric charge, and electric current. He could moreover prove that in a vacuum such a wave would travel at the speed of light, and thus light itself was a form of electromagnetic radiation. Maxwell's equations, which unify light, fields, and charge are one of the great milestones of theoretical physics. : 696–700 The work of many researchers enabled the use of electronics to convert signals into high frequency oscillating currents and, via suitably shaped conductors, electricity permits the transmission and reception of these signals via radio waves over very long distances.
Untersuchungen über die Ausbreitung der elektrischen Kraft (Electric Waves). 1893. Electromagnetic radiation Röntgen, Wilhelm (Germany).
|
Something that has all of the characteristics of life is considered to be what?
|
[
"molecule",
"organism",
"ecosystem",
"alive"
] |
D
|
There is not just one distinguishing feature that separates a living thing from a non-living thing. A cat moves but so does a car. A tree grows bigger, but so does a cloud. A cell has structure, but so does a crystal. Biologists define life by listing characteristics that living things share. Something that has all of the characteristics of life is considered to be alive. The duck decoy in Figure below may look like a duck, act like a duck in that it floats about, but it is not alive. The decoy cannot reproduce, respond to its environment, or breathe.
Besides actively participating in the current discussions on evolutionary theory and genetics, Mosterín has also tackled issues like the definition of life itself or the ontology of biological organisms and species. Following in Aristotle’s and Schrödinger’s footsteps, he has been asking the simple question: what is life? He has analyzed the main proposed definitions, based on metabolism, reproduction, thermodynamics, complexity and evolution, and found all of them wanting.
Aristotle describes popular accounts about what kind of life would be a eudaimonic one by classifying them into three most common types: a life dedicated to pleasure; a life dedicated to fame and honor; and a life dedicated to contemplation (NE I.1095b17-19). To reach his own conclusion about the best life, however, Aristotle tries to isolate the function of humans. The argument he develops here is accordingly widely known as "the function argument," and is among the most-discussed arguments made by any ancient philosopher.
Evidence suggests that life on Earth has existed for about 3.7 billion years. All known life forms share fundamental molecular mechanisms, and based on these observations, theories on the origin of life attempt to find a mechanism explaining the formation of a primordial single cell organism from which all life originates. There are many different hypotheses regarding the path that might have been taken from simple organic molecules via pre-cellular life to protocells and metabolism. Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction.
For example, the organism may be described at any of its component levels, including the atomic, molecular, cellular, histological (tissue), organ and organ system levels. Furthermore, at every level of the hierarchy, new functions necessary for the control of life appear. These new roles are not functions that the lower level components are capable of and are thus referred to as emergent properties. Every organism is organised, though not necessarily to the same degree. An organism can not be organised at the histological (tissue) level if it is not composed of tissues in the first place.
2. Due to this nature of existence, life is characterized by needs, wants, and pain. Thus, suffering is inescapable.
|
What do the letters in our blood types represent?
|
[
"alleles",
"genomes",
"proteins",
"iron levels"
] |
A
|
Another exception to Mendel's laws is a phenomenon called codominance . For example, our blood type shows codominance. Do you know what your blood type is? Are you A? O? AB? Those letters actually represent alleles. Unlike other traits, your blood type has three alleles, instead of two!.
What accounts for the differences in blood type? How ancient are the differences in blood types? What accounts for the large number of rare non ABO blood types?
Typeface anatomy describes the graphic elements that make up letters in a typeface.
For example, a red octagon is a common symbol for "STOP"; on maps, blue lines often represent rivers; and a red rose often symbolizes love and compassion. Numerals are symbols for numbers; letters of an alphabet may be symbols for certain phonemes; and personal names are symbols representing individuals. The academic study of symbols is semiotics. In cartography, an organized collection of symbols forms a legend for a map.
A basic division into four major types of epichoric alphabets is commonly made according to their different treatment of additional consonant letters for the aspirated consonants (/pʰ, kʰ/) and consonant clusters (/ks, ps/) of Greek. These four types are often conventionally labelled as "green", "red", "light blue" and "dark blue" types, based on a colour-coded map in a seminal 19th-century work on the topic, Studien zur Geschichte des griechischen Alphabets by Adolf Kirchhoff (1867). The "green" (or southern) type is the most archaic and closest to the Phoenician. The "red" (or western) type is the one that was later transmitted to the West and became the ancestor of the Latin alphabet, and bears some crucial features characteristic of that later development.
Blood is a fluid consisting of plasma, red blood cells, white blood cells, and platelets; it is circulated around the body carrying oxygen and nutrients to the tissues and collecting and disposing of waste materials. Circulated nutrients include proteins and minerals and other components include hemoglobin, hormones, and gases such as oxygen and carbon dioxide. These substances provide nourishment, help the immune system to fight diseases, and help maintain homeostasis by stabilizing temperature and natural pH.
|
The two stages of photosynthesis are the light reactions and what?
|
[
"digestive cycle",
"calvin cycle",
"respiratory cycle",
"reproductive cycle"
] |
B
|
The two stages of photosynthesis are the light reactions and the Calvin cycle. Do you see how the two stages are related?.
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.
In C3 plants, the first step in the light-independent reactions of photosynthesis is the fixation of CO2 by the enzyme RuBisCO to form 3-phosphoglycerate. However, RuBisCo has a dual carboxylase and oxygenase activity. Oxygenation results in part of the substrate being oxidized rather than carboxylated, resulting in loss of substrate and consumption of energy, in what is known as photorespiration. Oxygenation and carboxylation are competitive, meaning that the rate of the reactions depends on the relative concentration of oxygen and CO2.
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.
Embedded in the thylakoid membranes are important protein complexes which carry out the light reactions of photosynthesis. Photosystem II and photosystem I contain light-harvesting complexes with chlorophyll and carotenoids that absorb light energy and use it to energize electrons. Molecules in the thylakoid membrane use the energized electrons to pump hydrogen ions into the thylakoid space, decreasing the pH and turning it acidic.
|
What do living things need to survive?
|
[
"oxygen",
"nutrients",
"heat",
"molecules"
] |
B
|
There are three main ocean zones based on distance from shore. They are the intertidal zone , neritic zone , and oceanic zone . Distance from shore influences how many nutrients are in the water. Why? Most nutrients are washed into ocean water from land. Therefore, water closer to shore tends to have more nutrients. Living things need nutrients. So distance from shore also influences how many organisms live in the water.
It must also maintain the correct body temperature, an acceptable pressure on the body and deal with the body's waste products. Shielding against harmful external influences such as radiation and micro-meteorites may also be necessary. Components of the life-support system are life-critical, and are designed and constructed using safety engineering techniques.
Oxygen is essential to all life. Plants and phytoplankton photosynthesize water and carbon dioxide and water, both oxides, in the presence of sunlight to form sugars with the release of oxygen. The sugars are then turned into such substances as cellulose and (with nitrogen and often sulfur) proteins and other essential substances of life.
Besides actively participating in the current discussions on evolutionary theory and genetics, Mosterín has also tackled issues like the definition of life itself or the ontology of biological organisms and species. Following in Aristotle’s and Schrödinger’s footsteps, he has been asking the simple question: what is life? He has analyzed the main proposed definitions, based on metabolism, reproduction, thermodynamics, complexity and evolution, and found all of them wanting.
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.
Most of the structures that make up animals, plants and microbes are made from four basic classes of molecules: amino acids, carbohydrates, nucleic acid and lipids (often called fats). As these molecules are vital for life, metabolic reactions either focus on making these molecules during the construction of cells and tissues, or on breaking them down and using them to obtain energy, by their digestion. These biochemicals can be joined to make polymers such as DNA and proteins, essential macromolecules of life.
|
The denser regions of the electron cloud are called what?
|
[
"cores",
"lattices",
"orbitals",
"isotopes"
] |
C
|
Some regions of the electron cloud are denser than others. The denser regions are areas where electrons are most likely to be. These regions are called orbitals . Each orbital has a maximum of just two electrons. Different energy levels in the cloud have different numbers of orbitals. Therefore, different energy levels have different maximum numbers of electrons. Table below lists the number of orbitals and electrons for the first four energy levels. Energy levels farther from the nucleus have more orbitals. Therefore, these levels can hold more electrons.
The surface layer of these clouds is ionized. The source of ionisation is the population of massive stars (more than one hundred OB stars have been identified so far) that also occupy the central parsec. Sgr A West is surrounded by a massive, clumpy torus of cooler molecular gas, the Circumnuclear Disk (CND).
The Hot Ionized Medium (HIM), sometimes consisting of Coronal gas, in the temperature range 106 – 107 K emits X-rays. Stellar winds from young clusters of stars (often with giant or supergiant HII regions surrounding them) and shock waves created by supernovae inject enormous amounts of energy into their surroundings, which leads to hypersonic turbulence. The resultant structures – of varying sizes – can be observed, such as stellar wind bubbles and superbubbles of hot gas, by X-ray satellite telescopes. The Sun is currently traveling through the Local Interstellar Cloud, a denser region in the low-density Local Bubble.
The Hills cloud is thought to be a secondary reservoir of cometary nuclei and the source of replenishment for the tenuous outer cloud as the latter's numbers are gradually depleted through losses to the inner Solar System. The outer Oort cloud may have trillions of objects larger than 1 km (0.62 mi), and billions with diameters of 20-kilometre (12 mi).
Open cells are characterized by a cloud free region in the middle of the hexagonal formation with cloudy regions in the outer edge of the hexagon. The open cell will have slow descending motion in the middle with faster rising motion on the edges forming the hexagonal cloud shape. They tend to form over colder water such as those that exist off the Californian coast.
Ice clouds form at and below the Earth's high latitude mesopause (~90 km) where temperatures have been observed to fall as to below 100 K. It has been suggested that homogeneous nucleation of ice particles results in low density amorphous ice. Amorphous ice is likely confined to the coldest parts of the clouds and stacking disordered ice I is thought to dominate elsewhere in these polar mesospheric clouds.
|
In studying energy, what term do scientists use to refer to the matter and its environment involved in energy transfers?
|
[
"molecule",
"ecosystem",
"system",
"world"
] |
C
|
6.3 The Laws of Thermodynamics In studying energy, scientists use the term “system” to refer to the matter and its environment involved in energy transfers. Everything outside of the system is called the surroundings. Single cells are biological systems. Systems can be thought of as having a certain amount of order. It takes energy to make a system more ordered. The more ordered a system is, the lower its entropy. Entropy is a measure of the disorder of a system. As a system becomes more disordered, the lower its energy and the higher its entropy become. A series of laws, called the laws of thermodynamics, describe the properties and processes of energy transfer. The first law states that the total amount of energy in the universe is constant. This means that energy can’t be created or destroyed, only transferred or transformed. The second law of thermodynamics states that every energy transfer involves some loss of energy in an unusable form, such as heat energy, resulting in a more disordered system. In other words, no energy transfer is completely efficient and tends toward disorder.
Whatever name is applied, it deals with the ways in which plants respond to their environment and so overlaps with the field of ecology. Environmental physiologists examine plant response to physical factors such as radiation (including light and ultraviolet radiation), temperature, fire, and wind.
Thermodynamics deals with the fundamental laws of energy conversion and is drawn from theoretical Physics.
It is also the study of Earth and its neighbors in space. Some Earth scientists use their knowledge of the planet to locate and develop energy and mineral resources. Others study the impact of human activity on Earth's environment, and design methods to protect the planet.
Energy recovery from waste is using non-recyclable waste materials and extracting from it heat, electricity, or energy through a variety of processes, including combustion, gasification, pyrolyzation, and anaerobic digestion. This process is referred to as waste-to-energy. There are several ways to recover energy from waste. Anaerobic digestion is a naturally occurring process of decomposition where organic matter is reduced to a simpler chemical component in the absence of oxygen.
Particle physics is the study of the interactions of elementary particles at high energies, whilst physical cosmology studies the universe as a single physical entity. The interface between these two fields is sometimes referred to as particle cosmology. Particle physics must be taken into account in cosmological models of the early universe, when the average energy density was very high.
|
To measure what changes that occur in chemical reactions, chemists usually use a related thermodynamic quantity, calledenthalpy?
|
[
"energy",
"ion exchange",
"evaporation",
"entropy"
] |
A
|
(a) Initially, the system (a copper penny and concentrated nitric acid) is at atmospheric pressure. (b) When the penny is added to the nitric acid, the volume of NO2 gas that is formed causes the piston to move upward to maintain the system at atmospheric pressure. In doing so, the system is performing work on its surroundings. The symbol E in represents the internal energy of a system, which is the sum of the kinetic energy and potential energy of all its components. It is the change in internal energy that produces heat plus work. To measure the energy changes that occur in chemical reactions, chemists usually use a related thermodynamic quantity calledenthalpy (H) (from the Greek enthalpein, meaning “to warm”). The enthalpy of a system is defined as the sum of its internal energy E plus the product of its pressure Pand volume V:.
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.
Using the law of mass action, a defect's concentration can be related to its Gibbs free energy of formation, and the energy terms (enthalpy of formation) can be calculated given the defect concentration or vice versa.
In most cases of interest in chemical thermodynamics there are internal degrees of freedom and processes, such as chemical reactions and phase transitions, which create entropy in the universe unless they are at equilibrium or are maintained at a "running equilibrium" through "quasi-static" changes by being coupled to constraining devices, such as pistons or electrodes, to deliver and receive external work. Even for homogeneous "bulk" systems, the free-energy functions depend on the composition, as do all the extensive thermodynamic potentials, including the internal energy. If the quantities { Ni }, the number of chemical species, are omitted from the formulae, it is impossible to describe compositional changes.
A system is composed of particles, whose average motions define its properties, and those properties are in turn related to one another through equations of state. Properties can be combined to express internal energy and thermodynamic potentials, which are useful for determining conditions for equilibrium and spontaneous processes. With these tools, thermodynamics can be used to describe how systems respond to changes in their environment.
Thermodynamic work is measured by changes in a body's state variables, sometimes called work-like variables, other than temperature and entropy. Examples of work-like variables, which are ordinary macroscopic physical variables and which occur in conjugate pairs, are pressure – volume, and electric field – electric polarization. Temperature and entropy are a specifically thermodynamic conjugate pair of state variables.
|
A system in what state cannot spontaneously change, and therefore can do no work?
|
[
"equality",
"balance",
"equilibrium",
"stability"
] |
C
|
Microscopic kinetic fluctuations among particles cause entropic loss, and this energy is unavailable for work because these fluctuations occur randomly in all directions. The anthropocentric act is taken, in the eyes of some physicists and engineers today, when someone draws a hypothetical boundary, in fact, he says: "This is my system. What occurs beyond it is surroundings."
In open systems spontaneous structures can form. Their existence depends decisively on the system parameters.
In an isolated system, thermodynamic equilibrium by definition persists over an indefinitely long time. In classical physics it is often convenient to ignore the effects of measurement and this is assumed in the present account. To consider the notion of fluctuations in an isolated thermodynamic system, a convenient example is a system specified by its extensive state variables, internal energy, volume, and mass composition. By definition they are time-invariant.
As an example, consider an anti-lock braking system, directed by a microcontroller chip. The microcontroller has to make decisions based on brake temperature, speed, and other variables in the system. The variable "temperature" in this system can be subdivided into a range of "states": "cold", "cool", "moderate", "warm", "hot", "very hot". The transition from one state to the next is hard to define.
To help illustrate this, think of a simplified hypothetical scenario with Person A, who can exist in one of two states of the world. Assume Person A who is healthy and can work; this will be State X of the world. One day, an unfortunate accident occurs, person A no longer can work.
|
What is a species that plays an especially important role in it's community called?
|
[
"complement",
"Invasive",
"Leader",
"keystone"
] |
D
|
Some predator species are known as keystone species. A keystone species is one that plays an especially important role in its community. Major changes in the numbers of a keystone species affect the populations of many other species in the community. For example, some sea star species are keystone species in coral reef communities. The sea stars prey on mussels and sea urchins, which have no other natural predators. If sea stars were removed from a coral reef community, mussel and sea urchin populations would have explosive growth. This, in turn, would drive out most other species. In the end, the coral reef community would be destroyed.
The set of environmental features essential to that species' survival, is its "niche." (Ecology. Begon, Harper, Townsend)
Ecology (from Greek: οἶκος, "house", or "environment"; -λογία, "study of") is a branch of biology concerning interactions among organisms and their biophysical environment, which includes both biotic and abiotic components. Topics of interest include the biodiversity, distribution, biomass, and populations of organisms, as well as cooperation and competition within and between species. Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, pedogenesis, nutrient cycling, and niche construction, regulate the flux of energy and matter through an environment. These processes are sustained by organisms with specific life history traits.
Foster distinctive, attractive communities with a strong sense of place. Preserve open space, farmland, natural beauty, and critical environmental areas. Strengthen and direct development towards existing communities.
Frid adds, "Fish communities can be altered in a number of ways, for example they can decrease if particular sized individuals of a species are targeted, as this affects predator and prey dynamics. Fishing, however, is not the sole perpetrator of changes to marine life – pollution is another example No one factor operates in isolation and components of the ecosystem respond differently to each individual factor. "In contrast to the traditional approach of focusing on a single species, the ecosystem-based approach is organized in terms of ecosystem services.
These networks are defined by a set of pairwise interactions between and within a species that is used to understand the structure and function of larger ecological networks. By using network analysis we can discover and understand how these interactions link together within the system's network. It also allows us to quantify associations between individuals, which makes it possible to infer details about the network as a whole at the species and/or population level.
|
What term that shows how fast a population is growing includes new members added to the population over a given period, as well as old members removed from the population?
|
[
"birth rate",
"population density",
"growth rate",
"emigration"
] |
C
|
The population growth rate is how fast a population is growing. The letter r stands for the growth rate. The growth rate equals the number of new members added to the population in a year for each 100 members already in the population. The growth rate includes new members added to the population and old members removed from the population. Births add new members to the population. Deaths remove members from the population. The formula for population growth rate is:.
The change in total population over a period is equal to the number of births, minus the number of deaths, plus or minus the net amount of migration in a population. The number of births can be projected as the number of females at each relevant age multiplied by the assumed fertility rate. The number of deaths can be projected as the sum of the numbers of each age and sex in the population multiplied by their respective mortality rates. For many centuries, the overall population of the world changed relatively slowly: very broadly, the numbers of births were balanced by numbers of deaths (including high rates of infant immortality).
Examples of this emerging trend are Japan, whose population is currently (2022–2026) declining at the rate of 0.5% per year, and China, whose population has peaked and is currently (2022 – 2026) declining at the rate of about 0.04%. By 2050, Europe's population is projected to be declining at the rate of 0.3% per year.Population growth has declined mainly due to the abrupt decline in the global total fertility rate, from 5.3 in 1963 to 2.4 in 2019. The decline in the total fertility rate has occurred in every region of the world and is a result of a process known as demographic transition.
Demography and quantitative epidemiology are statistical fields that deal with counts or proportions of people, or rates of change in these. Counts and proportions are technically dimensionless, and so have no units of measurement, although identifiers such as "people", "births", "infections" and the like are used for clarity. Rates of change are counts per unit of time and strictly have inverse time dimensions (per unit of time).
Population size fluctuates at differing rates in differing regions. Nonetheless, population growth has been the long-standing trend on all inhabited continents, as well as in most individual states. During the 20th century, the global population saw its greatest increase in known history, rising from about 1.6 billion in 1900 to over 6 billion in 2000 as the whole world entered the early phases of what has come to be called the "demographic transition". Some of the key factors contributing to this increase included the lessening of the mortality rate in many countries by improved sanitation and medical advances, and a massive increase in agricultural productivity attributed to the Green Revolution.
There, the property relates to the population of an individual state, which determines the state's entitlement. A population-increase means that a state is entitled to more seats. This different property is described in the page state-population monotonicity.
|
The rings of what planet can be easily seen from earth?
|
[
"Venus",
"jupiter",
"Neptune",
"saturn"
] |
D
|
All of the outer planets have numerous moons. They also have planetary rings made of dust and other small particles. Only the rings of Saturn can be easily seen from Earth.
As the northern hemisphere is pointed towards the Sun only at aphelion, the sky there would likely remain blue. The rings of Saturn are almost certainly visible from the upper reaches of its atmosphere. The rings are so thin that from a position on Saturn's equator, they would be almost invisible. However, from anywhere else on the planet, they could be seen as a spectacular arc stretching across half the celestial hemisphere.Delta Octantis is the south pole star of Saturn. Its north pole is in the far northern region of Cepheus, about six degrees from Polaris.
Although the origins of planetary rings is not precisely known, they are believed to be the result of natural satellites that fell below their parent planet's Roche limit and were torn apart by tidal forces. The dwarf planets Haumea and Quaoar also have rings.No secondary characteristics have been observed around extrasolar planets. The sub-brown dwarf Cha 110913-773444, which has been described as a rogue planet, is believed to be orbited by a tiny protoplanetary disc and the sub-brown dwarf OTS 44 was shown to be surrounded by a substantial protoplanetary disk of at least 10 Earth masses.
The three rings have estimated dust masses 74, 168, and 245 times that of the Earth. According to Jiaqing Bi and coauthors, the outermost ring is the largest protoplanetary dust ring they are aware of. The dust rings are misaligned and the innermost dust ring is eccentric probably due to ongoing dynamical interactions between the triple stars and the circumtriple disk.
1978 – The Pioneer Venus probe maps the surface of Venus. 1978 – Peter Goldreich and Scott Tremaine present a Boltzmann equation model of planetary-ring dynamics for indestructible spherical ring particles that do not self-gravitate, and they find a stability requirement relation between ring optical depth and particle normal restitution coefficient. 1979 – Pioneer 11 flies by Saturn, providing the first ever closeup images of the planet and its rings.
Beneath this, the gases that make up the planet would be so hot that the planet would glow red. Clouds of silicates may exist in the atmosphere. The planet is tidally locked to its star, always presenting the same face to it. The planet (with Upsilon Andromedae b) was deemed a candidate for aperture polarimetry by Planetpol. It is also a candidate for "near-infrared characterisation.... with the VLTI Spectro-Imager".
|
What planet is a blue green color?
|
[
"uranus",
"Mars",
"sirius",
"Mercury"
] |
A
|
Uranus is a lot like Jupiter and Saturn. The planet is composed mainly of hydrogen and helium. There is a thick layer of gas on the outside. Further on the inside is liquid. But Uranus has a higher percentage of icy materials than Jupiter and Saturn. These materials include water, ammonia, and methane. Uranus is also different because of its blue-green color. Clouds of methane filter out red light. This leaves a blue-green color. The atmosphere of Uranus has bands of clouds. These clouds are hard to see in normal light. The result is that the planet looks like a plain blue ball.
Displayed at right is the color green earth. It is also known as terre verte and Verona green. It is an inorganic pigment derived from the minerals celadonite and glauconite.
Blue is a primary color across all models of color space. It is the color of the ocean and the sky; it often symbolizes serenity, stability, inspiration, or wisdom. It can be a calming color, and symbolize reliability.
Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called the Tyndall effect explains blue eyes.
Grundy et al. propose that the low density and albedo of Gǃkúnǁʼhòmdímà, combined with the fact that TNOs both larger and smaller – including comets – have a substantial fraction of rock in their composition, indicate that objects such as Gǃkúnǁʼhòmdímà and 174567 Varda (in the size range of 400–1000 km, with albedos less than ≈0.2 and densities of ≈1.2 g/cm3 or less) retain a degree of porosity in their physical structure, having never collapsed and differentiated into planetary bodies like higher density or higher albedo (and thus presumably resurfaced) 90482 Orcus and 50000 Quaoar, or at best are only partially differentiated; such objects would never have been in hydrostatic equilibrium and would not be dwarf planets at present.Gǃkúnǁʼhòmdímà exhibits an unusual disparity of visible and near-infrared colors: it appears reddish at visible wavelengths (V–R=0.62) while it appears bluer in the near-infrared (V–I=1.09). Hence, it does not fall within the four proposed taxonomic classes for TNO colors. Two other TNOs, namely (26375) 1999 DE9 and (145452) 2005 RN43, exhibit this same color behavior, implying an additional color group among TNOs.
The blue colour of the sky results from Rayleigh scattering, as the size of the gas particles in the atmosphere is much smaller than the wavelength of visible light. Rayleigh scattering is much greater for blue light than for other colours due to its shorter wavelength. As sunlight passes through the atmosphere, its blue component is Rayleigh scattered strongly by atmospheric gases but the longer wavelength (e.g. red/yellow) components are not.
|
The simplest class of organic compounds is the what?
|
[
"hydrocarbons",
"particles",
"Phenols",
"gas"
] |
A
|
isolating the individual components, preservationists are better able to determine the condition of an object and those books and documents most in need of immediate protection. The simplest class of organic compounds is the hydrocarbons, which consist entirely of carbon and hydrogen. Petroleum and natural gas are complex, naturally occurring mixtures of many different hydrocarbons that furnish raw materials for the chemical industry. The four major classes of hydrocarbons are the alkanes, which contain only carbon–hydrogen and carbon–carbon single bonds; the alkenes, which contain at least one carbon–carbon double bond; the alkynes, which contain at least one carbon–carbon triple bond; and the aromatic hydrocarbons, which usually contain rings of six carbon atoms that can be drawn with alternating single and double bonds. Alkanes are also called saturated hydrocarbons, whereas hydrocarbons that contain multiple bonds (alkenes, alkynes, and aromatics) are unsaturated.
An organic base is an organic compound which acts as a base. Organic bases are usually, but not always, proton acceptors. They usually contain nitrogen atoms, which can easily be protonated. For example, amines or nitrogen-containing heterocyclic compounds have a lone pair of electrons on the nitrogen atom and can thus act as proton acceptors. Examples include: pyridine alkylamines, such as methylamine imidazole benzimidazole histidine guanidine phosphazene bases hydroxides of quaternary ammonium cations or some other organic cations
For example, nitrogen mustards are well-known alkylating agents, but they are not simple hydrocarbons. In chemistry, alkyl is a group, a substituent, that is attached to other molecular fragments. For example, alkyl lithium reagents have the empirical formula Li(alkyl), where alkyl = methyl, ethyl, etc. A dialkyl ether is an ether with two alkyl groups, e.g., diethyl ether O(CH2CH3)2.
Diethylamine is the smallest and simplest molecule that features a supramolecular helix as its lowest energy aggregate. Other similarly sized hydrogen-bonding molecules favor cyclic structures.
The simplest organocadmium compound is dimethylcadmium. It is a linear molecule with a C-Cd bond length of 213 pm. Organocadmium compounds are typically sensitive to air, light, and moisture.
Neutral organic compounds tend to be hydrophobic; that is, they are less soluble in water than inorganic solvents. Exceptions include organic compounds that contain ionizable groups as well as low molecular weight alcohols, amines, and carboxylic acids where hydrogen bonding occurs. Otherwise, organic compounds tend to dissolve in organic solvents. Solubility varies widely with the organic solute and with the organic solvent.
|
Some meteorites are made of iron and nickel and are thought to be very similar to what part of the earth?
|
[
"crust",
"shelf",
"mantel",
"core"
] |
D
|
Scientists study meteorites to learn about Earth’s interior. Meteorites formed in the early solar system. These objects represent early solar system materials. Some meteorites are made of iron and nickel. They are thought to be very similar to Earth's core ( Figure below ). An iron meteorite is the closest thing to a sample of the core that scientists can hold in their hands!.
CR meteorites loosely resemble CM, but appear to have formed in a reducing environment, not an oxidizing one. It is held that they formed in a similar manner but different zone of the Solar System than CMs. Water content is lower than in CM; still, serpentinites, chlorite, and carbonates appear. GRO 95577 and Al Rais meteorites are exceptional CRs.
Due to planetary differentiation, the core region is believed to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.The alkali metals, due to their high reactivity, do not occur naturally in pure form in nature. They are lithophiles and therefore remain close to the Earth's surface because they combine readily with oxygen and so associate strongly with silica, forming relatively low-density minerals that do not sink down into the Earth's core. Potassium, rubidium and caesium are also incompatible elements due to their large ionic radii.Sodium and potassium are very abundant in earth, both being among the ten most common elements in Earth's crust; sodium makes up approximately 2.6% of the Earth's crust measured by weight, making it the sixth most abundant element overall and the most abundant alkali metal.
E chondrites are chondrites which are made primarily of enstatite and only account for 2% of meteorites that fall onto the Earth. E chondrites have an entirely different source rock than that of the ordinary chondrites. In analysis of kamacite in E chondrites it was found that they contain generally less nickel then average.
A meteorite mineral is a mineral found chiefly or exclusively within meteorites or meteorite-derived material. This is a list of those minerals, excluding minerals also commonly found in terrestrial rocks. As of 1997 there were approximately 295 mineral species which have been identified in meteorites.
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.
|
Which pathway carries somatosensory information from the face, head, mouth, and nasal cavity?
|
[
"posterior pathway",
"dual pathway",
"trigeminal pathway",
"cranial pathway"
] |
C
|
The trigeminal pathway carries somatosensory information from the face, head, mouth, and nasal cavity. As with the previously discussed nerve tracts, the sensory pathways of the trigeminal pathway each involve three successive neurons. First, axons from the trigeminal ganglion enter the brain stem at the level of the pons. These axons project to one of three locations. The spinal trigeminal nucleus of the medulla receives information similar to that carried by spinothalamic tract, such as pain and temperature sensations. Other axons go to either the chief sensory nucleus in the pons or the mesencephalic nuclei in the midbrain. These nuclei receive information like that carried by the dorsal column system, such as touch, pressure, vibration, and proprioception. Axons from the second neuron decussate and ascend to the thalamus along the trigeminothalamic tract. In the thalamus, each axon synapses with the third neuron in its respective pathway. Axons from the third neuron then project from the thalamus to the primary somatosensory cortex of the cerebrum. The sensory pathway for gustation travels along the facial and glossopharyngeal cranial nerves, which synapse with neurons of the solitary nucleus in the brain stem. Axons from the solitary nucleus then project to the ventral posterior nucleus of the thalamus. Finally, axons from the ventral posterior nucleus project to the gustatory cortex of the cerebral cortex, where taste is processed and consciously perceived. The sensory pathway for audition travels along the vestibulocochlear nerve, which synapses with neurons in the cochlear nuclei of the superior medulla. Within the brain stem, input from either ear is combined to extract location information from the auditory stimuli. Whereas the initial auditory stimuli received at the cochlea strictly represent the frequency—or pitch—of the stimuli, the locations of sounds can be determined by comparing information arriving at both ears.
The ophthalmic, maxillary and mandibular branches leave the skull through three separate foramina: the superior orbital fissure, the foramen rotundum and the foramen ovale, respectively. The ophthalmic nerve (V1) carries sensory information from the scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the nose (including the tip of the nose, except alae nasi), the nasal mucosa, the frontal sinuses and parts of the meninges (the dura and blood vessels). The maxillary nerve (V2) carries sensory information from the lower eyelid and cheek, the nares and upper lip, the upper teeth and gums, the nasal mucosa, the palate and roof of the pharynx, the maxillary, ethmoid and sphenoid sinuses and parts of the meninges. The mandibular nerve (V3) carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw, which is supplied by C2-C3), parts of the external ear and parts of the meninges.
The direction of their beat is targeted towards the pharynx, either upwards from the lower respiratory tract or downwards from the nasal structures.Goblet cells, so named because they are shaped like a wine goblet, are columnar epithelial cells that contain membrane-bound mucous granules and secrete mucus as part of the airway surface liquid (ASL), also known as the epithelial lining fluid, the composition of which is tightly regulated; the mucus helps maintain epithelial moisture and traps particulate material and pathogens moving through the airway. and determines how well mucociliary clearance works.The basal cells are small, nearly cuboidal that differentiate into the other cell types found within the epithelium. Basal cells respond to injury of the airway epithelium, migrating to cover a site denuded of differentiated epithelial cells, and subsequently differentiating to restore a healthy epithelial cell layer.
The olfactory nerve, located in the nose, provides a direct and relatively short route to the brain. Importantly, this route bypasses the protective barrier known as the blood-brain barrier. It seems that viruses and bacteria have identified this pathway as an easy way to gain access to the brain.
The nasal placode (or olfactory placode) gives rise to the olfactory epithelium of the nose. Two nasal placodes arise as thickened ectoderm from the frontonasal process. They give rise to the nose, the philtrum of the upper lip, and the primary palate.
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.
|
The amount of kinetic energy in a moving object depends directly on its mass and what else?
|
[
"volume",
"direction",
"density",
"velocity"
] |
D
|
The amount of kinetic energy in a moving object depends directly on its mass and velocity. An object with greater mass or greater velocity has more kinetic energy. You can calculate the kinetic energy of a moving object with this equation:.
The kinetic energy of a moving object is dependent on its velocity and is given by the equation ignoring special relativity, where Ek is the kinetic energy and m is the mass. Kinetic energy is a scalar quantity as it depends on the square of the velocity, however a related quantity, momentum, is a vector and defined by In special relativity, the dimensionless Lorentz factor appears frequently, and is given by where γ is the Lorentz factor and c is the speed of light. Escape velocity is the minimum speed a ballistic object needs to escape from a massive body such as Earth. It represents the kinetic energy that, when added to the object's gravitational potential energy (which is always negative), is equal to zero.
One implication is that the distribution of debris in orbit could render space activities and the use of satellites in specific orbital ranges difficult for many generations. Kinetic energy – In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity.
Substituting, we get: E k = E i + M V 2 2 . {\displaystyle E_{\text{k}}=E_{i}+{\frac {MV^{2}}{2}}.} Thus the kinetic energy of a system is lowest to center of momentum reference frames, i.e., frames of reference in which the center of mass is stationary (either the center of mass frame or any other center of momentum frame). In any different frame of reference, there is additional kinetic energy corresponding to the total mass moving at the speed of the center of mass. The kinetic energy of the system in the center of momentum frame is a quantity that is invariant (all observers see it to be the same).
If sacrificing the range is undesirable, it becomes necessary to carry that much more fuel. The energy density of a fuel per unit mass is called the specific energy of that fuel. In general an engine using that fuel will generate less kinetic energy due to inefficiencies and thermodynamic considerations—hence the specific fuel consumption of an engine will always be greater than its rate of production of the kinetic energy of motion.
Mass is no longer conserved independently, because it has been subsumed into the total relativistic energy. This makes the relativistic conservation of energy a simpler concept than in nonrelativistic mechanics, because the total energy is conserved without any qualifications. Kinetic energy converted into heat or internal potential energy shows up as an increase in mass. : 127
|
Cycling, shoveling snow and cross-country skiing are examples of what kind of heart-strengthening activity?
|
[
"aerobic",
"metabolism",
"anaerobic",
"exercise"
] |
A
|
When done regularly, aerobic activities, such as cycling, make the heart stronger. Other aerobic activities include mowing lawn, shoveling snow and cross country skiing.
Most beneficial effects of physical activity on cardiovascular disease mortality can be attained through moderate-intensity activity (40–60% of maximal oxygen uptake, depending on age). Persons who modify their behavior after myocardial infarction to include regular exercise have improved rates of survival. Persons who remain sedentary have the highest risk for all-cause and cardiovascular disease mortality. According to the American Heart Association, exercise reduces the risk of cardiovascular diseases, including heart attack and stroke.Some have suggested that increases in physical exercise might decrease healthcare costs, increase the rate of job attendance, as well as increase the amount of effort women put into their jobs.
Cross-country skiing is a form of skiing whereby skiers traverse snow-covered terrain without use of ski lifts or other assistance. Cross-country skiing is widely practiced as a sport and recreational activity; however, some still use it as a means of transportation. Variants of cross-country skiing are adapted to a range of terrain which spans unimproved, sometimes mountainous terrain to groomed courses that are specifically designed for the sport.
Recreational cross-country skiing includes ski touring and groomed-trail skiing, typically at resorts or in parklands. It is an accessible form of recreation for persons with vision and mobility impairments. A related form of recreation is dog skijoring—a winter sport where a cross-country skier is assisted by one or more dogs.
Healing with Form, Energy, and Light. Ithaca, New York: Snow Lion Publications. ISBN 1-55939-176-6.
Alpine skiing, or downhill skiing, is the pastime of sliding down snow-covered slopes on skis with fixed-heel bindings, unlike other types of skiing (cross-country, Telemark, or ski jumping), which use skis with free-heel bindings. Whether for recreation or for sport, it is typically practiced at ski resorts, which provide such services as ski lifts, artificial snow making, snow grooming, restaurants, and ski patrol. "Off-piste" skiers—those skiing outside ski area boundaries—may employ snowmobiles, helicopters or snowcats to deliver them to the top of a slope.
|
What take the shape of their container, and are relatively easy to compress?
|
[
"molecules",
"gases",
"semi-fluids",
"fluids"
] |
B
|
The story is quite different for gases. Gases take the shape of their container, and they are relatively easy to compress. There are fewer gas particles per unit volume than for the same substance in the liquid or solid form. In fact, the liquid form of a given material is generally several hundred times more dense than the gas form at normal pressures. Despite the large amounts of empty space, a sample of a gas contains many particles moving around, colliding and imparting force on their surroundings. For example, in a one mole sample of gas at 0°C and 1 atm of pressure, each cubic centimeter contains roughly 2.7 × 10 19 molecules. Each molecule participates in several billion collisions every second, moving only about 10-100 nanometers between collisions. Additionally, these gas particles move at very high speeds. For example, at 25°C, the average speed of hydrogen molecules in a sample of hydrogen gas is 1960 m/s.
The precursor mixture of powders and space-holders are compacted into a mold under a specified pressure. This can be achieved through uniaxial or isostatic processes. The pores resulting from this method are open and interconnected via windows between neighboring pores with the size of the pores partially dependent upon the coordination number and contact area of the resulting compact. Compaction pressure must be high enough to ensure sufficient mechanical strength for retention of pore geometry specified by the space-holder, but not too high enough as to cause deformation of the space-holder.
Random column packing used to characterize the maximum volume fraction of a solid object obtained when they are packed randomly. This method of packing has been used since the early 1820s; the types of packing used were originally made out of glass spheres. However, in 1850 they were replaced by a more porous pumice stone and pieces of coke.
If the midpoints of the spheres are arranged throughout 3D space, the packing is termed a cluster packing. Real-life approximations include fruit being packed in multiple layers in a box.
The column can be filled with random dumped packing (creating a random packed column) or with structured packing sections, which are arranged or stacked (creating a stacked packed column). In the column, liquids tend to wet the surface of the packing and the vapors pass across this wetted surface, where mass transfer takes place. Packing material can be used instead of trays to improve separation in distillation columns.
The quality of the inlet air is critical to the quality of the product as many types of impurity are impracticable to remove after compression. Condensed water vapour is usually removed between stages after cooling the compressed air to improve efficiency of compression. High pressure compressors may be set up with large storage cylinders and a filling panel for portable cylinders, and may be associated with gas blending equipment. Low pressure diving compressors usually supply compressed air to a gas distribution panel via a volume tank, which helps compensate for fluctuations in supply and demand. Air from the gas panel is supplied to the diver through the diver's umbilical.
|
What is moving air called?
|
[
"steam",
"clouds",
"humidity",
"wind"
] |
D
|
Moving air, like moving water, causes erosion. Moving air is called wind.
It is an oral consonant, which means air is allowed to escape through the mouth only. It is a lateral consonant, which means it is produced by directing the airstream over the sides of the tongue, rather than down the middle. The airstream mechanism is pulmonic, which means it is articulated by pushing air solely with the intercostal muscles and diaphragm, as in most sounds.
It is an oral consonant, which means air is allowed to escape through the mouth only. It is a central consonant, which means it is produced by directing the airstream along the center of the tongue, rather than to the sides. The airstream mechanism is pulmonic, which means it is articulated by pushing air solely with the intercostal muscles and diaphragm, as in most sounds.
It is an oral consonant, which means air is allowed to escape through the mouth only. It is a central consonant, which means it is produced by directing the airstream along the center of the tongue, rather than to the sides. The airstream mechanism is pulmonic, which means it is articulated by pushing air solely with the intercostal muscles and diaphragm, as in most sounds.
To take in air sharply in that way is to implode a sound.However, probably more typically, there is no movement of air at all, which contrasts with the burst of the pulmonary plosives. This is the case with many of the Kru languages, for example. That means that implosives are phonetically sonorants (not obstruents) as the concept of sonorant is usually defined.
Moving away from the shore. 2. (of a wind) Blowing from the land to the sea.
|
What property makes bone marrow cells ideal for gene therapy?
|
[
"behavior reproduction",
"lifelong reproduction",
"irreversible reproduction",
"Matching"
] |
B
|
Gene therapy is being studied as a potential treatment.
Gene therapy might eventually be used to cure the cause of beta cell destruction, thereby curing the new diabetes patient before the beta cell destruction is complete and irreversible. Gene therapy can be used to turn duodenum cells and duodenum adult stem cells into beta cells which produce insulin and amylin naturally. By delivering beta cell DNA to the intestine cells in the duodenum, a few intestine cells will turn into beta cells, and subsequently adult stem cells will develop into beta cells. This makes the supply of beta cells in the duodenum self-replenishing, and the beta cells will produce insulin in proportional response to carbohydrates consumed.
Gene therapy is used to reinstate the function of a mutated or deleted gene type. When tumor suppressor genes are altered in a way that results in less or no expression, several severe problems can arise for the host. This is why tumor suppressor genes have commonly been studied and used for gene therapy. The two main approaches used currently to introduce genetic material into cells are viral and non-viral delivery methods.
Potential uses include the treatment of diabetes and heart disease. The cells are being studied to be used as clinical therapies, models of genetic disorders, and cellular/DNA repair. However, adverse effects in the research and clinical processes such as tumors and unwanted immune responses have also been reported.
The transcription and translation machinery of the cell is then in charge of therapy and administers either a wild-type protein or an anti-drug (Fig. 3). The rule (1) may even be generalised to involve mutations from different proteins allowing a combined diagnosis and therapy. In this way, computational genes might allow implementation in situ of a therapy as soon as the cell starts developing defective material. Computational genes combine the techniques of gene therapy which allows to replace in the genome an aberrant gene by its healthy counterpart, as well as to silence the gene expression (similar to antisense technology).
|
What is the name of the two metalloids in the carbon group called?
|
[
"titantium and copper",
"silicon and germanium",
"silicon and gold",
"silver and gold"
] |
B
|
Group 14 is called the carbon group. This group contains two metalloids: silicon and germanium. Carbon is a nonmetal, and the remaining elements in this group are metals.
In the area of metal carbonyl clusters, a prototypical octahedral cluster is 2−, which is obtained by heating iron pentacarbonyl with sodium. Some of the CO ligands are bridging and many are terminal. A carbide ligand resides at the center of the cluster.
Many other names for sets of elements are in common use; others have been used throughout history. These sets usually do not aim to cover the whole periodic table (as for example period does), and often overlap or have boundaries that differ between authors. Some examples: Metals and nonmetals Metalloids – Variously-defined group of elements with properties intermediate between metals and nonmetals.In alphabetic order: Coinage metals – Various metals used to mint coins, primarily the group 11 elements Cu, Ag, and Au. Earth metal – Old historic term, usually referred to the metals of groups 3 and 13, although sometimes others such as beryllium and chromium are included as well.
Most of its chemistry is nonmetallic; it has a relatively high ionization energy and, compared to most metals, a relatively high electronegativity. Carbon can form anions such as C4− (methanide), C2–2 (acetylide), and C3–4 (sesquicarbide or allylenide), in compounds with metals of main groups 1–3, and with the lanthanides and actinides. Its oxide CO2 forms carbonic acid H2CO3.
Published without approval and formally discredited or not approved, yet. Mainly: pyrochlore, tourmaline and amphibole supergroups, arrojadite, and yftisite-(Y). IMA/CNMNC revisions generate hypothetical solid solution endmembers. group – a name used to designate a group of species, sometimes only a mineral group name.
Chromium is the fourth transition metal found on the periodic table, and has an electron configuration of 3d5 4s1. It is also the first element in the periodic table whose ground-state electron configuration violates the Aufbau principle. This occurs again later in the periodic table with other elements and their electron configurations, such as copper, niobium, and molybdenum. This occurs because electrons in the same orbital repel each other due to their like charges.
|
What is the name of the zone where water is deeper than 200 meters called?
|
[
"transition zone",
"euphotic zone",
"aphotic zone",
"eccentric zone"
] |
C
|
The aphotic zone is water deeper than 200 meters. This is where too little sunlight penetrates for photosynthesis to occur. As a result, producers must make "food" by chemosynthesis , or the food must drift down from the water above.
The boundary at which there is sufficient sub-terranean pressure to completely saturate the ground with water is called the water table. The area above the water table is called the “unsaturated zone,” while the area below it is called the “saturated zone” . In the saturated zone, pressure is the primary force driving the flow of water.
The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately 200 meters (660 ft) in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated environment for marine life, from plankton up to large fish and corals, while physical oceanography sees it as where the oceanic system interacts with the coast.
As with oceans, the benthic zone is the floor of the lake, composed of accumulated sunken organic matter. The littoral zone is the zone bordering the shore; light penetrates easily and aquatic plants thrive. The pelagic zone represents the broad mass of water, down as far as the depth to which no light penetrates.
The bathypelagic and abyssopelagic zones are aphotic, meaning that no light penetrates this area of the ocean. These zones make up about 75% of the inhabitable ocean space.The epipelagic zone (0–200 m) is the area where light penetrates the water and photosynthesis occurs. This is also known as the photic zone. Because this typically extends only a few hundred meters below the water, the deep sea, about 90% of the ocean volume, is in darkness. The deep sea is also an extremely hostile environment, with temperatures that rarely exceed 3 °C (37 °F) and fall as low as −1.8 °C (29 °F) (with the exception of hydrothermal vent ecosystems that can exceed 350 °C, or 662 °F), low oxygen levels, and pressures between 20 and 1000 atm (between 2 and 100 MPa).
The abyssal zone covers the abyssal plains between 4,000 and 6,000 m. Lastly, the hadal zone corresponds to the hadalpelagic zone, which is found in oceanic trenches.Distinct boundaries between ocean surface waters and deep waters can be drawn based on the properties of the water. These boundaries are called thermoclines (temperature), haloclines (salinity), chemoclines (chemistry), and pycnoclines (density).
|
Diagnosing and treating cancer is a beneficial use of what potentially dangerous energy?
|
[
"thermal",
"mechanical",
"solar",
"radiation"
] |
D
|
Radiation has several important uses, including diagnosing and treating cancer.
Conducting research into whether a chemical causes cancer is difficult, because "suspect chemicals cannot ethically be given to people to see if they cause cancer. People exposed in the past can be studied, but information about the dose and timing may be sketchy. Animal studies can provide useful information, but do not always apply to humans. And people are often exposed to mixtures of chemicals that may interact in complex ways, with effects that may also vary depending on an individual's genetic makeup".Samantha King says that prevention research is minimized by the breast cancer industry because there is no way to make money off of cases of breast cancer that do not happen, whereas a mammography imaging system that finds more possible cancers, or a "magic bullet" that kills confirmed cancers, would be highly profitable.
The most popular alternative cancer therapies include restrictive diets, mind-body interventions, bioelectromagnetics, nutritional supplements, and herbs. The popularity and prevalence of different treatments varies widely by region. Cancer Research UK warns that alternative treatments may interact with conventional treatment, may increase the side effects of medication, and can give people false hope.
Overdiagnosed patients cannot benefit from the detection and treatment of their "cancer" because the cancer was never destined to cause symptoms or death. They can only be harmed. There are three categories of harm associated with overdiagnosis: Physical effects of unnecessary diagnosis and treatment: All medical interventions have side effects. This is particularly true of cancer treatments.
Some practitioners of alternative medicine have promoted "oxygen therapy" as a cure for many human ailments including AIDS, Alzheimer's disease and cancer. According to the American Cancer Society, "available scientific evidence does not support claims that putting oxygen-releasing chemicals into a person's body is effective in treating cancer", and some of these treatments can be dangerous.
Potential uses include the treatment of diabetes and heart disease. The cells are being studied to be used as clinical therapies, models of genetic disorders, and cellular/DNA repair. However, adverse effects in the research and clinical processes such as tumors and unwanted immune responses have also been reported.
|
Many adults and some children suffer from a deficiency of lactase. these individuals are said to be lactose intolerant because they cannot digest the lactose found in what?
|
[
"fruit",
"milk",
"peanuts",
"meat"
] |
B
|
Many adults and some children suffer from a deficiency of lactase. These individuals are said to be lactose intolerant because they cannot digest the lactose found in milk. A more serious problem is the genetic disease galactosemia, which results from the absence of an enzyme needed to convert galactose to glucose. Certain bacteria can metabolize lactose, forming lactic acid as one of the products. This reaction is responsible for the “souring” of milk.
People with congenital lactase deficiency cannot digest lactose from birth, so cannot digest breast milk. This genetic defect is characterized by a complete lack of lactase (alactasia). About 40 cases have been reported worldwide, mainly limited to Finland. Before the 20th century, babies born with congenital lactase deficiency often did not survive, but death rates decreased with soybean-derived infant formulas and manufactured lactose-free dairy products.
It is broken down when consumed into its constituent parts by the enzyme lactase during digestion. Children have this enzyme but some adults no longer form it and they are unable to digest lactose.
The locus can be expressed as 2q21. The lactase deficiency also could be linked to certain heritages and varies widely. A 2016 study of over 60,000 participants from 89 countries found regional prevalence of lactose malabsorption was "64% (54–74) in Asia (except Middle East), 47% (33–61) in eastern Europe, Russia, and former Soviet Republics, 38% (CI 18–57) in Latin America, 70% (57–83) in the Middle East, 66% (45–88) in northern Africa, 42% (13–71) in northern America, 45% (19–71) in Oceania, 63% (54–72) in sub-Saharan Africa, and 28% (19–37) in northern, southern and western Europe."
In order to assess lactose intolerance, intestinal function is challenged by ingesting more dairy products than can be readily digested. Clinical symptoms typically appear within 30 minutes, but may take up to two hours, depending on other foods and activities. Substantial variability in response (symptoms of nausea, cramping, bloating, diarrhea, and flatulence) is to be expected, as the extent and severity of lactose intolerance varies among individuals.The next step is to determine whether it is due to primary lactase deficiency or an underlying disease that causes secondary lactase deficiency. Physicians should investigate the presence of undiagnosed coeliac disease, Crohn disease, or other enteropathies when secondary lactase deficiency is suspected and infectious gastroenteritis has been ruled out.Lactose intolerance is distinct from milk allergy, an immune response to cow's milk proteins.
Lactose intolerance is found in most adults, except for specific geographic populations, notably those of European descent. Many who benefit from a low FODMAP diet need not restrict fructose or lactose. It is possible to identify these two conditions with hydrogen and methane breath testing, thus eliminating the necessity for dietary compliance.
|
Three-prong plugs, circuit breakers, and gfci outlets are safety features that recognize the danger of what?
|
[
"electricity",
"heat",
"magnetism",
"gravity"
] |
A
|
Because electricity can be so dangerous, safety features are built into modern electric circuits and devices. They include three-prong plugs, circuit breakers, and GFCI outlets. You can read about these three safety features in the Figure below . You can learn more about electric safety features in the home by watching the video at this URL: http://www. dailymotion. com/video/x6fg5i_basics-of-your-home-s-electrical-sy_school .
For example, protection devices and revenue metering may use separate CTs to provide isolation between metering and protection circuits and allows current transformers with different characteristics (accuracy, overload performance) to be used for the devices. In the United States, the National Electrical Code (NEC) requires residual current devices in commercial and residential electrical systems to protect outlets installed in "wet" locations such as kitchens and bathrooms, as well as weatherproof outlets installed outdoors. Such devices, most commonly ground fault circuit interrupters (GFCIs), typically run both the 120-volt energized conductor and the neutral return conductor through a current transformer, with the secondary coil connected to a trip device.
The international standard IEC 61508 Functional safety of electrical/electronic/programmable electronic safety-related systems. IEC 62061 Safety of machinery - Functional safety of safety-related electrical, electronic and programmable electronic control systems and ISO 13849 Safety of machinery — Safety-related parts of control systems are also the basis for Profisafe. The international standard IEC 61784-3 defines different protocols for safe systems with comparable properties. Profisafe is part 3 of this collection of standards and is thus defined as IEC 61784-3-3:2021 CPF 3.
These devices have a Functional Earth "FE". This differs from a protective earth ground in that it does not offer shock protection from a hazardous voltage. However, it does help to mitigate electromagnetic noise or EMI. This is often important in Audio and Medical design. Note as they also include double insulation it means that users will not be able to come into contact with any live parts.
PRIMARY RESPONSIBILITIES * Probabilistic Safety Assessment. * Deterministic Safety Analysis. * Safety Review of Indian Nuclear Power Plants.
Electric shock drownings are most commonly caused by improper electrical connections on boats and piers. By law, all connections near water are required to have working ground fault circuit interruption technology, GFCI. These devices break the electrical circuit if any stray current fails to return to the source connection. If GFCI devices are missing or faulty, it is possible for current to leak into the water.
|
Catabolic reactions break down large organic molecules into smaller molecules, releasing the energy contained in what?
|
[
"molecular bonds",
"liquid bonds",
"crystals bonds",
"chemical bonds"
] |
D
|
Catabolic Reactions Catabolic reactions break down large organic molecules into smaller molecules, releasing the energy contained in the chemical bonds. These energy releases (conversions) are not 100 percent efficient. The amount of energy released is less than the total amount contained in the molecule. Approximately 40 percent of energy yielded from catabolic reactions is directly transferred to the high-energy molecule adenosine triphosphate (ATP). ATP, the energy currency of cells, can be used immediately to power molecular machines that support cell, tissue, and organ function. This includes building new tissue and repairing damaged tissue. ATP can also be stored to fulfill future energy demands. The remaining 60 percent of the energy released from catabolic reactions is given off as heat, which tissues and body fluids absorb. Structurally, ATP molecules consist of an adenine, a ribose, and three phosphate groups (Figure 24.2). The chemical bond between the second and third phosphate groups, termed a high-energy bond, represents the greatest source of energy in a cell. It is the first bond that catabolic enzymes break when cells require energy to do work. The products of this reaction are a molecule of adenosine diphosphate (ADP) and a lone phosphate group (Pi). ATP, ADP, and Pi are constantly being cycled through reactions that build ATP and store energy, and reactions that break down ATP and release energy.
In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperature and concentrations present within a cell. The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays and reactions between elementary particles, as described by quantum field theory.
The fluid catalytic cracking process breaks large hydrocarbons by their conversion to carbocations, which undergo myriad rearrangements. Figure 2 is a very simplified schematic diagram that exemplifies how the process breaks high boiling, straight-chain alkane (paraffin) hydrocarbons into smaller straight-chain alkanes as well as branched-chain alkanes, branched alkenes (olefins) and cycloalkanes (naphthenes). The breaking of the large hydrocarbon molecules into smaller molecules is more technically referred to by organic chemists as scission of the carbon-to-carbon bonds. As depicted in Figure 2, some of the smaller alkanes are then broken and converted into even smaller alkenes and branched alkenes such as the gases ethylene, propylene, butylenes, and isobutylenes.
In some species of fish, including goldfish and carp, it provides energy when oxygen is scarce (along with lactic acid fermentation).Before fermentation, a glucose molecule breaks down into two pyruvate molecules (glycolysis). The energy from this exothermic reaction is used to bind inorganic phosphates to ADP, which converts it to ATP, and convert NAD+ to NADH. The pyruvates break down into two acetaldehyde molecules and give off two carbon dioxide molecules as waste products. The acetaldehyde is reduced into ethanol using the energy and hydrogen from NADH, and the NADH is oxidized into NAD+ so that the cycle may repeat. The reaction is catalyzed by the enzymes pyruvate decarboxylase and alcohol dehydrogenase.
The sugars and other molecular components produced by the autotrophs are then broken down, releasing stored solar energy, and giving the heterotroph the energy required for survival. This process is known as cellular respiration.
In the process of cation attachment, cations (typically H+ or Na+) attach themselves to analyte molecules; the desorption of the cation attachment (e.g., MNa+) can then be realized through the emitter heating and high field. The ionization of more polar organic molecules (e.g., ones with aliphatic hydroxyl or amino groups) in FD-MS typically go through this mechanism.
|
In qualitative analysis, reagents are added to an unknown chemical mixture in order to induce what?
|
[
"motion",
"precipitation",
"sunlight",
"erosion"
] |
B
|
Selective precipitation can also be used in qualitative analysis. In this method, reagents are added to an unknown chemical mixture in order to induce precipitation. Certain reagents cause specific ions to precipitate out; therefore, the addition of the reagent can be used to determine whether the ion is present in the solution.
The sequestration medium reagent is typically composed of an equal mixture of oleic acid (cis-9-octadecenoic acid) and Kelex-100 (ethyl-methyl-octyl, 8-quinolinol), however other chemicals may be used to perform similar functions. After deployment, the immobilized metal species can then be extracted from the outer membrane.
After eleven paper editions over 68 years, Reagent Chemicals became an electronic resource in 2017. The publication is updated several times a year to include new reagents and methods of analysis. Changes are published online six months prior to becoming an official standard, allowing manufacturers to adjust their labels or processes.While the full details of most reagents are behind a paywall, that for acetone is publicly available to showcase a typical entry.
Dragendorff's reagent is a color reagent to detect alkaloids in a test sample or as a stain for chromatography plates. Alkaloids, if present in the solution of sample, will react with Dragendorff's reagent and produce an orange or orange-red precipitate. This reagent was invented by the German pharmacologist, Johann Georg Dragendorff (1836–1898) at the University of Dorpat.
These chemicals are designated as those that are used in the manufacture of the controlled substances and are important to the manufacture of the substances:
The toxic equivalency of a mixture is defined by the sum of the concentrations of individual compounds (Ci) multiplied by their relative toxicity (TEF):
|
While climate change in earth history was due to natural processes, what is primarily to blame for recent global warming?
|
[
"human actions",
"wars",
"volcanos",
"factories"
] |
A
|
Climate change in Earth history was due to natural processes. Recent global warming is due mainly to human actions. The burning of fossil fuels releases greenhouse gases into the air. This creates greater greenhouse effect and global warming.
These, together with other anthropogenic drivers, are "extremely likely" (where that means more than 95% probability) to have been the dominant cause of the observed global warming since the mid-20th century.It said that: Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks. Reporting on the publication of the report, The Guardian said that: In the end it all boils down to risk management.
—; Kunzig, Robert (2008), Fixing Climate: What Past Climate Changes Reveal About the Current Threat--and How to Counter It, Hill and Wang, US/Profile Books, UK, ISBN 978-0-8090-4501-3. — (2010), The Great Ocean Conveyor, Discovering the Trigger for Abrupt Climate Change, Princeton University Press, ISBN 978-0-691-14354-5. — (2016), A Geochemist in his Garden of Eden (PDF), Eldigio Press.
While water vapor is a greenhouse gas, the very short atmospheric lifetime of water vapor (about 10 days) compared to that of CO2 (hundreds of years) means that CO2 is the primary driver of increasing temperatures; water vapour acts as a feedback, not a forcing, mechanism. Water vapor has been incorporated into climate models since their inception in the late 1800s.Climate denial groups may also argue that global warming stopped recently, a global warming hiatus, or that global temperatures are actually decreasing, leading to global cooling. These arguments are based on short term fluctuations, and ignore the long term pattern of warming.These groups often point to natural variability, such as sunspots and cosmic rays, to explain the warming trend. According to these groups, there is natural variability that will abate over time, and human influences have little to do with it. These factors are already taken into account when developing climate models, and the scientific consensus is that they cannot explain the observed warming trend.At a May 2018 meeting of the United States House Committee on Science, Space, and Technology, Alabama's Representative Mo Brooks claimed that sea level rise is caused not by melting glaciers but rather by coastal erosion and silt that flows from rivers into the ocean.Climate change denial literature often features the suggestion that we should wait for better technologies before addressing climate change, when they will be more affordable and effective.
Shaftel, Holly; Jackson, Randal; Callery, Susan; Bailey, Daniel, eds. (7 July 2020). "Overview: Weather, Global Warming and Climate Change".
In July 2007, the International Union of Geodesy and Geophysics (IUGG) adopted a resolution titled "The Urgency of Addressing Climate Change". In it, the IUGG concurs with the "comprehensive and widely accepted and endorsed scientific assessments carried out by the Intergovernmental Panel on Climate Change and regional and national bodies, which have firmly established, on the basis of scientific evidence, that human activities are the primary cause of recent climate change". They state further that the "continuing reliance on combustion of fossil fuels as the world's primary source of energy will lead to much higher atmospheric concentrations of greenhouse gases, which will, in turn, cause significant increases in surface temperature, sea level, ocean acidification, and their related consequences to the environment and society".
|
What is the simplest life cycle?
|
[
"haploid life cycle",
"diploid life cycle",
"binary life cycle",
"metamorphic cycle"
] |
A
|
The haploid life cycle ( Figure below ) is the simplest life cycle. It is found in many single-celled organisms. Organisms with a haploid life cycle spend the majority of their lives as haploid gametes. When the haploid gametes fuse, they form a diploid zygote. It quickly undergoes meiosis to produce more haploid gametes that repeat the life cycle.
Evidence suggests that life on Earth has existed for about 3.7 billion years. All known life forms share fundamental molecular mechanisms, and based on these observations, theories on the origin of life attempt to find a mechanism explaining the formation of a primordial single cell organism from which all life originates. There are many different hypotheses regarding the path that might have been taken from simple organic molecules via pre-cellular life to protocells and metabolism. Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by organization, metabolism, growth, adaptation, response to stimuli and reproduction.
(1970). Cycles; selected writings. Pittsburgh: Foundation for the Study of Cycles.
If this incorporation occurred only once in four billion years or is otherwise unlikely, then life on most planets remains simple. An alternative view is that the evolution of mitochondria was environmentally triggered, and that mitochondria-containing organisms appeared soon after the first traces of atmospheric oxygen.The evolution and persistence of sexual reproduction is another mystery in biology.
Besides actively participating in the current discussions on evolutionary theory and genetics, Mosterín has also tackled issues like the definition of life itself or the ontology of biological organisms and species. Following in Aristotle’s and Schrödinger’s footsteps, he has been asking the simple question: what is life? He has analyzed the main proposed definitions, based on metabolism, reproduction, thermodynamics, complexity and evolution, and found all of them wanting.
Since an organism can't put energy towards doing these simultaneously, many organisms have a period where energy is put just toward growth, followed by a period where energy is focused on reproduction, creating a separation of the two in the life cycle. Thus, the end of the period of growth marks the beginning of the period of reproduction. Another fundamental trade-off associated with reproduction is between mating effort and parenting effort.
|
What keeps the moon orbiting earth?
|
[
"Coriolis effect",
"the Sun",
"axial tilt",
"gravity"
] |
D
|
Gravity keeps the Moon orbiting Earth. Gravity keeps the planets orbiting the Sun.
For these constituents, the moon (or sun) can be thought of as orbiting a non-rotating earth in a plane with the appropriate inclination to the equator. Then the tidal "bulge" lags behind the orbiting moon thus decelerating it in its orbit (bringing it closer to the earth), and by angular momentum conservation, the earth's rotation must accelerate. But this argument is qualitative, and a quantitative resolution of the conflicting conclusions is still needed.
The moon gains energy and gradually spirals outward, while the primary rotates more slowly over time. The Earth and its Moon are one example of this configuration. Today, the Moon is tidally locked to the Earth; one of its revolutions around the Earth (currently about 29 days) is equal to one of its rotations about its axis, so it always shows one face to the Earth.
The delay in the responses causes the tidal bulge to be carried forward. Consequently, the line through the two bulges is tilted with respect to the Earth-Moon direction exerting torque between the Earth and the Moon. This torque boosts the Moon in its orbit and slows the rotation of Earth.
In a second study, René Heller then included the effect of eclipses into this concept as well as constraints from a satellite's orbital stability. He found that, depending on a moon's orbital eccentricity, there is a minimum mass for stars to host habitable moons at around 0.2 solar masses. Taking as an example the smaller Europa, at less than 1% the mass of the Earth, Lehmer et al. found if it were to end up near to Earth orbit it would only be able to hold onto its atmosphere for a few million years.
Of the natural satellites in the Solar System's habitable zone —the Moon, two Martian satellites (though some estimates put those outside it) and numerous Minor-planet moons — all lack the conditions for surface water. Unlike the Earth, all planetary mass moons of the Solar System are tidally locked and it is not yet known to what extent this and tidal forces influence habitability. Research suggests that deep biospheres like that of Earth are possible.
|
What are formed by the attraction between oppositely charged ions?
|
[
"inept bonds",
"soluble bonds",
"ionic bonds",
"magnetic bonds"
] |
C
|
Ionic bonds are formed by the attraction between oppositely charged ions.
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.
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.
An important example of this interaction is hydration of ions in water which give rise to hydration enthalpy. The polar water molecules surround themselves around ions in water and the energy released during the process is known as hydration enthalpy. The interaction has its immense importance in justifying the stability of various ions (like Cu2+) in water. An ion–induced dipole force consists of an ion and a non-polar molecule interacting. Like a dipole–induced dipole force, the charge of the ion causes distortion of the electron cloud on the non-polar molecule.
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).
The ions are positive and move towards the negative inner cage. Those that miss the wires of the inner cage fly through the center of the device at high speeds and can fly out the other side of the inner cage. As the ions move outward, a Coulomb force impels them back towards the center.
|
What produces hormones that directly regulate body processes?
|
[
"hippocampus",
"lymph glands",
"pancreas",
"hypothalamus"
] |
D
|
The hypothalamus also produces hormones that directly regulate body processes. For example, it produces antidiuretic hormone. This hormone travels to the kidneys and stimulates them to conserve water by producing more concentrated urine.
Adrenocorticotropic hormone release is triggered by corticotropin-releasing hormone and inhibited by rising glucocorticoid levels. The gonadotropins—follicle-stimulating hormone and luteinizing hormone regulate the functions of the gonads in both sexes. Follicle-stimulating hormone stimulates sex cell production; luteinizing hormone stimulates gonadal hormone production.
Flux through the glucose cycle is regulated by several hormones including insulin and glucagon as well as allosteric regulation of both hexokinase and glucose 6-phosphatase.
Cortical development of the adrenal gland is regulated mostly by ACTH, a hormone produced by the pituitary gland that stimulates cortisol synthesis. During midgestation, the fetal zone occupies most of the cortical volume and produces 100–200 mg/day of DHEA-S, an androgen and precursor of both androgens and estrogens (female sex hormones). Adrenal hormones, especially glucocorticoids such as cortisol, are essential for prenatal development of organs, particularly for the maturation of the lungs. The adrenal gland decreases in size after birth because of the rapid disappearance of the fetal zone, with a corresponding decrease in androgen secretion.
The intermediate lobe synthesizes and secretes melanocyte-stimulating hormone. The posterior pituitary (or neurohypophysis) is a lobe of the gland that is functionally connected to the hypothalamus by the median eminence via a small tube called the pituitary stalk (also called the infundibular stalk or the infundibulum). It regulates hydroelectrolytic stability (by secreting ADH), uterine contraction during labor and human attachment (by secreting oxytocin). Hormones secreted from the pituitary gland help to control growth, blood pressure, energy management, all functions of the sex organs, thyroid glands and metabolism as well as some aspects of pregnancy, childbirth, breastfeeding, water/salt concentration at the kidneys, temperature regulation and pain relief.
Both hormones regulate hormone-sensitive lipase and acetyl-CoA carboxylase. Hormone-sensitive lipase produces diglycerides from triglycerides, freeing a fatty acid molecule for oxidation. Acetyl-CoA carboxylase catalyzes the production of malonyl-CoA from acetyl-CoA.
|
Comparing anatomy, and characterizing the similarities and differences, provides evidence of what process?
|
[
"regression",
"devolution",
"emergence",
"evolution"
] |
D
|
Take a close look at this gorilla hand. The similarities to a human hand are remarkable. Comparing anatomy, and characterizing the similarities and differences, provides evidence of evolution.
In anatomy, two anatomical structures are considered to be analogous when they serve similar functions but are not evolutionarily related, such as the legs of vertebrates and the legs of insects. Analogous structures are the result of independent evolution and should be contrasted with structures which shared an evolutionary line.
colony comparative biology The use of comparative methods to study the similarities and differences between two or more biological organisms (e.g. two organisms from the same time period but different taxa, or two organisms from the same taxon but different times in evolutionary history). The side-by-side comparison of morphological or molecular characteristics of different organisms is the basis from which biologists infer the organisms' genetic relatedness and their natural histories. It is a fundamental tool in many biological disciplines, including anatomy, physiology, paleontology, and phylogenetics.
The morphology and function of a complex organ like the brain are the result of numerous biochemical and biophysical processes interacting in a highly complex manner across multiple scales in space and time (Vallender et al., 2008). Most of the genes known to control these processes during brain development, maturation and aging are highly conserved (Holland, 2003), though some show polymorphisms (cf. Meda et al., 2008), and pronounced differences at the cognitive level abound even amongst closely related species, or between individuals within a species (Roth and Dicke, 2005). In contrast, variations in macroscopic brain anatomy (i.e., at a level of detail still discernible by the naked human eye) are sufficiently conserved to allow for comparative analyses, yet diverse enough to reflect variations within and between individuals and species: As morphological analyses that compare brains at different onto-genetic or pathogenic stages can reveal important information about the progression of normal or abnormal development within a given species, cross-species comparative studies have a similar potential to reveal evolutionary trends and phylogenetic relationships. Given that the imaging modalities commonly employed for brain morphometric investigations are essentially of a molecular or even sub-atomic nature, a number of factors may interfere with derived quantification of brain structures. These include all of the parameters mentioned in "Applications" but also the state of hydration, hormonal status, medication and substance abuse.
The visual pathway that determines objects shapes, sizes, colors and other definitive characteristics is called the ventral stream. Each of these two streams runs independent of one another so that the visual system may process one without the other (like in brain damage for instance) or both simultaneously. The two streams do not depend on one another, so if one is functioning manipulatively, the other can still send its information through.
A plant morphologist makes comparisons between structures in many different plants of the same or different species. Making such comparisons between similar structures in different plants tackles the question of why the structures are similar. It is quite likely that similar underlying causes of genetics, physiology, or response to the environment have led to this similarity in appearance.
|
What is the second most abundant element in the earth's crust?
|
[
"nitrogen",
"helium",
"silicon",
"carbon"
] |
C
|
What is this intricate orb? It is the greatly magnified skeleton of single-celled ocean organisms call radiolarian. The skeleton is made of an element that is extremely common on Earth. In fact, it is the second most abundant element in Earth’s crust. It is also one of the most common elements in the entire universe. What is this important element? Its name is silicon, and it belongs to a class of elements called metalloids.
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.
Due to planetary differentiation, the core region is believed to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.The alkali metals, due to their high reactivity, do not occur naturally in pure form in nature. They are lithophiles and therefore remain close to the Earth's surface because they combine readily with oxygen and so associate strongly with silica, forming relatively low-density minerals that do not sink down into the Earth's core. Potassium, rubidium and caesium are also incompatible elements due to their large ionic radii.Sodium and potassium are very abundant in earth, both being among the ten most common elements in Earth's crust; sodium makes up approximately 2.6% of the Earth's crust measured by weight, making it the sixth most abundant element overall and the most abundant alkali metal.
As such, iron is the most abundant element in the core of red giants, and is the most abundant metal in iron meteorites and in the dense metal cores of planets such as Earth. It is also very common in the universe, relative to other stable metals of approximately the same atomic weight. Iron is the sixth most abundant element in the universe, and the most common refractory element.
Pyrrhotite requires both iron and sulfur to form. Iron is the fourth most abundant element in the Earth's continental crust (average abundance of 5.63 % or 56,300 mg/kg in the crust), and so the majority of rocks have sufficient iron abundance to form pyrrhotite. However, because sulfur is less abundant (average abundance of 0.035 % or 350 mg/kg in the crust), the formation of pyrrhotite is generally controlled by sulfur abundance. Also, the mineral pyrite is both the most common and most abundant sulfide mineral in the Earth's crust.
Iron is a chemical element with the symbol Fe (from Latin ferrum 'iron') and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, just ahead of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust, being mainly deposited by meteorites in its metallic state, with its ores also being found there.
|
Which kind of genetics approach involves mutating or deleting genes provides researchers with clues about gene function?
|
[
"reverse genetics",
"possible genetics",
"impossible genetics",
"inverse genetics"
] |
A
|
Watch this short video (http://openstaxcollege. org/l/transgenic) explaining how scientists create a transgenic animal. Although the classic methods of studying the function of genes began with a given phenotype and determined the genetic basis of that phenotype, modern techniques allow researchers to start at the DNA sequence level and ask: "What does this gene or DNA element do?" This technique, called reverse genetics, has resulted in reversing the classical genetic methodology. One example of this method is analogous to damaging a body part to determine its function. An insect that loses a wing cannot fly, which means that the wing’s function is flight. The classic genetic method compares insects that cannot fly with insects that can fly, and observes that the non-flying insects have lost wings. Similarly in a reverse genetics approach, mutating or deleting genes provides researchers with clues about gene function. Alternately, reverse genetics can be used to cause a gene to overexpress itself to determine what phenotypic effects may occur.
Gene therapy is being studied as a potential treatment.
A broad class of various procedures used to identify features of an individual's particular chromosomes, genes, or proteins in order to determine parentage or ancestry, diagnose vulnerabilities to heritable diseases, or detect mutant alleles associated with increased risks of developing genetic disorders. Genetic testing is widely used in human medicine, agriculture, and biological research. genetic variability Sometimes used interchangeably with genetic variation.
The hijack of an enhancer from another gene allows the analysis of the function of that enhancer. This, especially if the reporter gene is for a fluorescent protein, can be used to help map expression of the mutated gene through the organism, and is a very powerful tool. It is a useful tool for looking at gene expression patterns (temporally and spatially).
This approach involves targeting a specific gene with a mutation and then observing what phenotype develops. The mutation can be designed to inactivate the gene or only allow it to become active under certain conditions.
The transcription and translation machinery of the cell is then in charge of therapy and administers either a wild-type protein or an anti-drug (Fig. 3). The rule (1) may even be generalised to involve mutations from different proteins allowing a combined diagnosis and therapy. In this way, computational genes might allow implementation in situ of a therapy as soon as the cell starts developing defective material. Computational genes combine the techniques of gene therapy which allows to replace in the genome an aberrant gene by its healthy counterpart, as well as to silence the gene expression (similar to antisense technology).
|
More than half of all known organisms are what?
|
[
"insects",
"mammals",
"enzymes",
"spiders"
] |
A
|
The majority of arthropods are insects (Class Insecta). In fact, more than half of all known organisms are insects. There may be more than 10 million insect species in the world, although most of them have not yet been identified. In terms of their numbers and diversity, insects clearly are the dominant animals in the world.
As a consequence, phages are found almost everywhere.As a rule of thumb, many phage biologists expect that phage population densities will exceed bacterial densities by a ratio of 10-to-1 or more (VBR or virus-to-bacterium ratio; see for a summary of actual data). As there exist estimates of bacterial numbers on Earth of approximately 1030, there consequently is an expectation that 1031 or more individual virus (mostly phage) particles exist , making phages the most numerous category of "organisms" on our planet. Bacteria (along with archaea) appear to be highly diverse and there possibly are millions of species. Phage-ecological interactions therefore are quantitatively vast: huge numbers of interactions. Phage-ecological interactions are also qualitatively diverse: There are huge numbers of environment types, bacterial-host types, and also individual phage types
Most are marine animals, although a few species live in fresh water and even fewer on land. Clitellates (about 10,000 species ). These have few or no chetae per segment, and no nuchal organs or parapodia.
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.
The organisms are preserved in good condition and shape. The diversity and number of co-inclusions help to draw conclusions about mutual relations and co-existence. == References ==
There is strong empirical evidence and new consensus that biodiversity (i.e., the richness of species and their interactions) pervasively influences the functioning of Earth's ecosystems, including ecosystem productivity. However, this research has focused almost exclusively on macroorganisms. Because microbial symbionts are integral parts of most living organisms, the understanding of how microbial symbionts contribute to host performance and adaptability needs broadening.
|
For what purpose does liver use the excess carbohydrate?
|
[
"process sugar",
"dilute carbohydrates",
"convert starches",
"to synthesize glycogen"
] |
D
|
Obesity With obesity at high rates in the United States, there is a public health focus on reducing obesity and associated health risks, which include diabetes, colon and breast cancer, and cardiovascular disease. How does the food consumed contribute to obesity? Fatty foods are calorie-dense, meaning that they have more calories per unit mass than carbohydrates or proteins. One gram of carbohydrates has four calories, one gram of protein has four calories, and one gram of fat has nine calories. Animals tend to seek lipid-rich food for their higher energy content. Greater amounts of food energy taken in than the body’s requirements will result in storage of the excess in fat deposits. Excess carbohydrate is used by the liver to synthesize glycogen. When glycogen stores are full, additional glucose is converted into fatty acids. These fatty acids are stored in adipose tissue cells—the fat cells in the mammalian body whose primary role is to store fat for later use. The rate of obesity among children is rapidly rising in the United States. To combat childhood obesity and ensure that children get a healthy start in life, in 2010 First Lady Michelle Obama launched the Let’s Move! campaign. The goal of this campaign is to educate parents and caregivers on providing healthy nutrition and encouraging active lifestyles in future generations. This program aims to involve the entire community, including parents, teachers, and healthcare providers to ensure that children have access to healthy foods—more fruits, vegetables, and whole grains—and consume fewer calories from processed foods. Another goal is to ensure that children get physical activity. With the increase in television viewing and stationary pursuits such as video games, sedentary lifestyles have become the norm. Visit www. letsmove. gov to learn more.
The primary treatment goal is prevention of hypoglycemia and the secondary metabolic derangements by frequent feedings of foods high in glucose or starch (which is readily digested to glucose). To compensate for the inability of the liver to provide sugar, the total amount of dietary carbohydrate should approximate the 24-hour glucose production rate. The diet should contain approximately 65–70% carbohydrate, 10–15% protein, and 20–25% fat. At least a third of the carbohydrates should be supplied through the night, so that a young child goes no more than 3–4 hours without carbohydrate intake.
After a meal, some of the fatty acids taken up by the liver is converted into very low density lipoproteins (VLDL) and again secreted into the blood.In addition, when a long time has passed since the last meal, the concentration of fatty acids in the blood decreases, which triggers adipocytes to release stored fatty acids into the blood as free fatty acids, in order to supply e.g. muscle cells with energy. In any case, also the fatty acids secreted from cells are anew taken up by other cells in the body, until entering fatty acid metabolism.
Fructose consumption (in contrast to glucose) activates both SREBP-1c and ChREBP in an insulin independent manner. Although glucose can be converted into glycogen in the liver, fructose invariably increases de novo lipogenesis in the liver, elevating plasma triglycerides, more than glucose.
Food and Drug Administration. Conversely, it is also used as a bacterial culture medium. Its presence in blood can be used as an effective marker to measure liver disease. It is also widely used as a sweetener in the food industry and as a humectant in pharmaceutical formulations. Because of its three hydroxyl groups, glycerol is miscible with water and is hygroscopic in nature.
If the carbohydrate meal consists of a food (which doesn't need to be carbohydrate itself), that requires prolonged vigorous chewing, and then some time to be digested, for instance parboiled long grain rice, chewing may suddenly become very slow and difficult halfway through the meal. When a carbohydrate-rich food has been eaten before AMP has been eliminated from muscle cells, when bulk absorption starts, plenty of glucose becomes available in the blood, is taken up by muscle cells, is added to the glycogen store, but then immediately becomes liberated by the still up-regulated myophosphorylase. The resulting excess of glucose is metabolized down to lactic acid (the body cannot increase aerobic metabolism in an instant), recharging all AMP to ATP.
|
Saturn is made mostly of helium and what else?
|
[
"nitrogen",
"carbon",
"hydrogen",
"hydrogen"
] |
C
|
Saturn’s composition is similar to Jupiter's. The planet is made mostly of hydrogen and helium. These elements are gases in the outer layers and liquids in the deeper layers. Saturn may also have a small solid core. Saturn's upper atmosphere has clouds in bands of different colors. These clouds rotate rapidly around the planet. But Saturn has fewer storms than Jupiter. Thunder and lightning have been seen in the storms on Saturn ( Figure below ).
There are several hypotheses for how a helium planet might form.
Helium also sometimes serves as the base gas, with small amounts of argon and carbon dioxide added. However, because it is less dense than air, helium is less effective at shielding the weld than argon—which is denser than air. It also can lead to arc stability and penetration issues, and increased spatter, due to its much more energetic arc plasma.
Oberon is the second-largest and second-most massive of the Uranian moons after Titania, and the ninth-most massive moon in the Solar System. It is the tenth-largest moon by size however, since Rhea, the second-largest moon of Saturn and the ninth-largest moon, is nearly the same size as Oberon although it is about 0.4% larger, despite Oberon having more mass than Rhea. Oberon's density of 1.63 g/cm3, which is higher than the typical density of Saturn's satellites, indicates that it consists of roughly equal proportions of water ice and a dense non-ice component. The latter could be made of rock and carbonaceous material including heavy organic compounds.
Gas giants consist mostly of hydrogen and helium. The Solar System's gas giants, Jupiter and Saturn, have heavier elements making up between 3 and 13 percent of their mass. Gas giants are thought to consist of an outer layer of molecular hydrogen, surrounding a layer of liquid metallic hydrogen, with a probable molten core with a rocky composition.
Underneath the thick atmospheres of the planets Uranus and Neptune, it is expected that these planets are composed of oceans of hot high-density fluid mixtures of water, ammonia and other volatiles. The gaseous outer layers of Jupiter and Saturn transition smoothly into oceans of supercritical hydrogen. The atmosphere of Venus is 96.5% carbon dioxide, which is a supercritical fluid at its surface.
|
What are alkenes organic compounds that contain one or more double or triple bonds between carbon atoms described as?
|
[
"saturated",
"insulated",
"unsaturated",
"strong"
] |
C
|
Alkenes Organic compounds that contain one or more double or triple bonds between carbon atoms are described as unsaturated. You have likely heard of unsaturated fats. These are complex organic molecules with long chains of carbon atoms, which contain at least one double bond between carbon atoms. Unsaturated hydrocarbon molecules that contain one or more double bonds are called alkenes. Carbon atoms linked by a double bond are bound together by two bonds, one σ bond and one π bond. Double and triple bonds give rise to a different geometry around the carbon atom that participates in them, leading to important differences in molecular shape and properties. The differing geometries are responsible for the different properties of unsaturated versus saturated fats. Ethene, C2H4, is the simplest alkene. Each carbon atom in ethene, commonly called ethylene, has a trigonal planar structure. The second member of the series is propene (propylene) (Figure 20.7); the butene isomers follow in the series. Four carbon atoms in the chain of butene allows for the formation of isomers based on the position of the double bond, as well as a new form of isomerism.
alkane Also paraffin. Any fully saturated acyclic hydrocarbon, i.e. one in which all carbon–carbon bonds are single bonds. alkene Also olefin.
The bonding is often denoted using the hapticity formalism. Keto-alkenes are tetrahapto ligands that stabilize highly unsaturated low valent metals as found in (benzylideneacetone)iron tricarbonyl and tris(dibenzylideneacetone)dipalladium(0). Metal alkene complexes.
Compounds with formal C≡O triple bonds do not exist except for carbon monoxide, which has a very short, strong bond (112.8 pm), and acylium ions, R–C≡O+ (typically 110-112 pm). Such triple bonds have a very high bond energy, even higher than N–N triple bonds. Oxygen can also be trivalent, for example in triethyloxonium tetrafluoroborate. : 343
In organic chemistry a carbonate can also refer to a functional group within a larger molecule that contains a carbon atom bound to three oxygen atoms, one of which is double bonded. These compounds are also known as organocarbonates or carbonate esters, and have the general formula ROCOOR′, or RR′CO3. Important organocarbonates include dimethyl carbonate, the cyclic compounds ethylene carbonate and propylene carbonate, and the phosgene replacement, triphosgene.
This is a partial list of molecules that contain 23 carbon atoms.
|
Electrons in covalent compounds are shared between the two atoms, unlike the case in what type of bonds?
|
[
"horizontal bonds",
"weak bonds",
"ionic bonds",
"soluble bonds"
] |
C
|
The two materials do have at least one thing in common. The atoms in the materials are held together by covalent bonds. These bonds consist of electrons shared between two or more atoms. Unlike ionic bonds, where electrons are either lost or gained by an atom to form charged ions, electrons in covalent compounds are shared between the two atoms, giving rise to properties that are quite different from those seen in ionic materials.
There are several types of structures for covalent substances, including individual molecules, molecular structures, macromolecular structures and giant covalent structures. Individual molecules have strong bonds that hold the atoms together, but generally, there are negligible forces of attraction between molecules. Such covalent substances are usually gases, for example, HCl, SO2, CO2, and CH4.
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.
Atomic orbitals (except for s orbitals) have specific directional properties leading to different types of covalent bonds. Sigma (σ) bonds are the strongest covalent bonds and are due to head-on overlapping of orbitals on two different atoms. A single bond is usually a σ bond. Pi (π) bonds are weaker and are due to lateral overlap between p (or d) orbitals.
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.
The two theories represent two ways to build up the electron configuration of the molecule. For valence bond theory, the atomic hybrid orbitals are filled with electrons first to produce a fully bonded valence configuration, followed by performing a linear combination of contributing structures (resonance) if there are several of them. In contrast, for molecular orbital theory a linear combination of atomic orbitals is performed first, followed by filling of the resulting molecular orbitals with electrons.The two approaches are regarded as complementary, and each provides its own insights into the problem of chemical bonding. As valence bond theory builds the molecular wavefunction out of localized bonds, it is more suited for the calculation of bond energies and the understanding of reaction mechanisms.
|
What is the resistance of a liquid to flow called?
|
[
"turbulence",
"permeability",
"elasticity",
"viscosity"
] |
D
|
Viscosity (η) is the resistance of a liquid to flow. Some liquids, such as gasoline, ethanol, and water, flow very readily and hence have a low viscosity. Others, such as motor oil, molasses, and maple syrup, flow very slowly and have a high viscosity. The two most common methods for evaluating the viscosity of a liquid are (1) to measure the time it takes for a quantity of liquid to flow through a narrow vertical tube and (2) to measure the time it takes steel balls to fall through a given volume of the liquid. The higher the viscosity, the slower the liquid flows through the tube and the steel balls fall. Viscosity is expressed in units of the poise (mPa·s); the higher the number, the higher the viscosity. The viscosities of some representative liquids are listed in Table 11.4 "Surface Tension, Viscosity, Vapor Pressure (at 25°C Unless Otherwise Indicated), and Normal Boiling Points of Common Liquids" and show a correlation between viscosity and intermolecular forces. Because a liquid can flow only if the molecules can move past one another with minimal resistance, strong intermolecular attractive forces make it more difficult for molecules to move with respect to one another. The addition of a second hydroxyl group to ethanol, for example, which produces ethylene glycol (HOCH2CH2OH), increases the viscosity 15-fold. This effect is due to the increased number of hydrogen bonds that can form between hydroxyl groups in adjacent molecules, resulting in dramatically stronger intermolecular attractive forces.
== Thermal conductivity of liquid ==
A hydraulic analogy is sometimes used to describe Ohm's law. Water pressure, measured by pascals (or PSI), is the analog of voltage because establishing a water pressure difference between two points along a (horizontal) pipe causes water to flow. The water volume flow rate, as in liters per second, is the analog of current, as in coulombs per second. Finally, flow restrictors—such as apertures placed in pipes between points where the water pressure is measured—are the analog of resistors.
When not in use, the stick is secured within the tube. Fluid – In physics, a fluid is a liquid, gas, or other material that continuously deforms (flows) under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear force applied to them.
By nature, it is liquid. It ripples.
For many applications, such a task requires the definition of a solid of revolution shape that experiences minimal resistance to rapid motion through such a fluid medium. Nozzle – is a device designed to control the direction or characteristics of a fluid flow (especially to increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying cross-sectional area, and it can be used to direct or modify the flow of a fluid (liquid or gas). Nozzles are frequently used to control the rate of flow, speed, direction, mass, shape, and/or the pressure of the stream that emerges from them. In a nozzle, the velocity of fluid increases at the expense of its pressure energy.
|
The mass of atoms is based on the number of protons and neutrons in what?
|
[
"nucleus",
"electrons",
"molecules",
"components"
] |
A
|
Atoms have a mass that is based largely on the number of protons and neutrons in their nucleus.
By definition, any two atoms with an identical number of protons in their nuclei belong to the same chemical element. Atoms with equal numbers of protons but a different number of neutrons are different isotopes of the same element. For example, all hydrogen atoms admit exactly one proton, but isotopes exist with no neutrons (hydrogen-1, by far the most common form, also called protium), one neutron (deuterium), two neutrons (tritium) and more than two neutrons. The known elements form a set of atomic numbers, from the single-proton element hydrogen up to the 118-proton element oganesson.
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 typically consist of protons and neutrons, although exotic nuclei may consist of other baryons, such as hypertriton which contains a hyperon. These baryons (protons, neutrons, hyperons, etc.) which comprise the nucleus are called nucleons. Each type of nucleus is called a "nuclide", and each nuclide is defined by the specific number of each type of nucleon. "Isotopes" are nuclides which have the same number of protons but differing numbers of neutrons.
This word was formed by replacing the p in isotope with n for neutron. Nuclides that have the same mass number are called isobars. Nuclides that have the same neutron excess are called isodiaphers.Chemical properties are primarily determined by proton number, which determines which chemical element the nuclide is a member of; neutron number has only a slight influence.
One mole of atoms of any element always has the same number of atoms (about 6.022×1023). This number was chosen so that if an element has an atomic mass of 1 u, a mole of atoms of that element has a mass close to one gram. Because of the definition of the unified atomic mass unit, each carbon-12 atom has an atomic mass of exactly 12 Da, and so a mole of carbon-12 atoms weighs exactly 0.012 kg.
|
Where do polychaete worms live?
|
[
"in tide pools",
"attached to marine life",
"in coral reefs",
"the ocean floor"
] |
D
|
Annelids called polychaete worms live on the ocean floor. They may be filter feeders, predators, or scavengers. The amazing feather duster worm in Figure below is a polychaete that has a fan-like crown of tentacles for filter feeding.
One notable polychaete, the Pompeii worm (Alvinella pompejana), is endemic to the hydrothermal vents of the Pacific Ocean. Pompeii worms are among the most heat-tolerant complex animals known. A recently discovered genus, Osedax, includes a species nicknamed the "bone-eating snot flower".
Riftia pachyptila, commonly known as the giant tube worm and less commonly known as the giant beardworm, is a marine invertebrate in the phylum Annelida (formerly grouped in phylum Pogonophora and Vestimentifera) related to tube worms commonly found in the intertidal and pelagic zones. R. pachyptila lives on the floor of the Pacific Ocean near hydrothermal vents. The vents provide a natural ambient temperature in their environment ranging from 2 to 30 °C, and this organism can tolerate extremely high hydrogen sulfide levels. These worms can reach a length of 3 m (9 ft 10 in), and their tubular bodies have a diameter of 4 cm (1.6 in). Its common name "giant tube worm" is, however, also applied to the largest living species of shipworm, Kuphus polythalamius, which despite the name "worm", is a bivalve mollusc rather than an annelid.
Siboglinidae is a family of polychaete annelid worms whose members made up the former phyla Pogonophora and Vestimentifera (the giant tube worms). The family is composed of around 100 species of vermiform creatures which live in thin tubes buried in sediment (Pogonophora) or in tubes attached to hard substratum (Vestimentifera) at ocean depths ranging from 100 to 10,000 m (300 to 32,800 ft). They can also be found in association with hydrothermal vents, methane seeps, sunken plant material, and whale carcasses. The first specimen was dredged from the waters of Indonesia in 1900. These specimens were given to French zoologist Maurice Caullery, who studied them for nearly 50 years.
In addition to the fish host, C. shasta infects a freshwater polychaete worm. Actinospores are released from the worm, and infect fish, on contact, in the water column. Neither horizontal (fish to fish), nor vertical (fish to egg) transmissions have been documented under laboratory conditions, suggesting that the worm host is necessary for completion of the life cycle. Spores are released back into freshwater system after its fish host dies, however the complete life cycle, host and vector interaction is not fully understood (especially the ecology of the polychaete host).Research indicates that the potential for infection is enhanced when water temperatures are high, water flow is low, or numbers of infectious C. shasta are relatively high. Infection rates appear to be higher in or below still water environments than riverine ones.
Many sub-families of the marine fish Oreosomatidae, including the Allocyttus, Neocyttus, and Pseudocyttus (collectively referred to as the Oreos) have been reported to live up to 170 years, based on otolith-increment estimates and radiometric dating. The deepsea hydrocarbon seep tubeworm Lamellibrachia luymesi (Annelida, Polychaeta) lives for more than 170 years. Geoduck, a species of saltwater clam native to the Puget Sound, have been known to live more than 160 years.
|
What is the study of how and why plants and animals live where they do?
|
[
"geomorphology",
"heredity",
"lithography",
"biogeography"
] |
D
|
Biogeography is the study of how and why plants and animals live where they do. It provides more evidence for evolution. Let’s consider the camel family as an example.
Ecology (from Greek: οἶκος, "house", or "environment"; -λογία, "study of") is a branch of biology concerning interactions among organisms and their biophysical environment, which includes both biotic and abiotic components. Topics of interest include the biodiversity, distribution, biomass, and populations of organisms, as well as cooperation and competition within and between species. Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living components of their environment. Ecosystem processes, such as primary production, pedogenesis, nutrient cycling, and niche construction, regulate the flux of energy and matter through an environment. These processes are sustained by organisms with specific life history traits.
Whatever name is applied, it deals with the ways in which plants respond to their environment and so overlaps with the field of ecology. Environmental physiologists examine plant response to physical factors such as radiation (including light and ultraviolet radiation), temperature, fire, and wind.
These applications include: Studying the diversity of organisms and the differentiation between extinct and living creatures. Biologists study the well-understood relationships by making many different diagrams and "trees" (cladograms, phylogenetic trees, phylogenies, etc.). Including the scientific names of organisms, species descriptions and overviews, taxonomic orders, and classifications of evolutionary and organism histories.
The science is most advanced in Europe, Africa and Asia. In the United States this concept was largely rejected in favour of studying environments in more individualistic terms regarding species, where specific associations of plants occur randomly because of individual preferences and responses to gradients, and there are no sharp boundaries between phytocoenoses. The terminology 'plant community' is usually used in the US for a habitat consisting of a number of specific plant species. It has been a successful approach in the scope of contemporary vegetation science because of its highly descriptive and predictive powers, and its usefulness in nature management issues.
It is also the study of Earth and its neighbors in space. Some Earth scientists use their knowledge of the planet to locate and develop energy and mineral resources. Others study the impact of human activity on Earth's environment, and design methods to protect the planet.
|
Muscles that position the pectoral girdle are located either on the anterior thorax or on this?
|
[
"posterior thorax",
"posterior thorax",
"inferred thorax",
"analogous thorax"
] |
A
|
Muscles That Position the Pectoral Girdle Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax (Figure 11.22 and Table 11.8). The anterior muscles include the subclavius, pectoralis minor, and serratus anterior. The posterior muscles include the trapezius, rhomboid major, and rhomboid minor. When the rhomboids are contracted, your scapula moves medially, which can pull the shoulder and upper limb posteriorly.
Its fibers run perpendicular to the external oblique muscle, beginning in the thoracolumbar fascia of the lower back, the anterior 2/3 of the iliac crest (upper part of hip bone) and the lateral half of the inguinal ligament. The muscle fibers run from these points superomedially (up and towards midline) to the muscle's insertions on the inferior borders of the 10th through 12th ribs and the linea alba. In males, the cremaster muscle is also attached to the internal oblique.
The piriformis muscle originates from the superior margin of the greater sciatic notch (as well as the sacroiliac joint capsule and the sacrotuberous ligament and part of the spine and sacrum. The superior gemellus muscle arises from the outer surface of the ischial spine The obturator internus muscle arises from the inner surface of the antero-lateral wall of the hip bone, where it surrounds the greater part of the obturator foramen, being attached to the inferior rami of the pubis and ischium, and at the side to the inner surface of the hip bone below and behind the pelvic brim, reaching from the upper part of the greater sciatic foramen above and behind to the obturator foramen below and in front. It also arises from the pelvic surface of the obturator membrane except in the posterior part, from the tendinous arch, and to a slight extent from the obturator fascia, which covers the muscle. The inferior gemellus muscle arises from the upper part of the tuberosity of the ischium, immediately below the groove for the obturator internus tendon. The obturator externus muscle arises from the margin of bone immediately around the medial side of the obturator foramen, from the rami of the pubis, and the inferior ramus of the ischium; it also arises from the medial two-thirds of the outer surface of the obturator membrane, and from the tendinous arch.
The piriformis muscle originates from the anterior (front) surface of the sacrum by three fleshy digitations attached to the second, third, and fourth sacral vertebra.It also arises from the superior margin of the greater sciatic notch, the gluteal surface of the ilium (near the posterior inferior iliac spine), the sacroiliac joint capsule, and (sometimes) the sacrotuberous ligament (more specifically, the superior part of the pelvic surface of this ligament).
It is accompanied by venae comitantes (accompanying veins). It gives branches to the muscles of the anterior compartment.
Pelvis - AP only in the UK, with SIJ projections (prone) on special request.Sacrum and Coccyx: In the US, if both bones are to be examined separate cephalad and caudad AP axial projections are obtained for the sacrum and coccyx respectively as well as a single Lateral of both bones.Ribs: In the US, common rib projections are based on the location of the area of interest. These are obtained with shorter wavelengths/higher frequencies/higher levels of radiation than a standard CXR.Anterior area of interest - a PA chest X-ray, a PA projection of the ribs, and a 45 degree Anterior Oblique with the non-interest side closest to the image receptor. Posterior area of interest - a PA chest X-ray, an AP projection of the ribs, and a 45 degree Posterior Oblique with the side of interest closest to the image receptor.Sternum. The standard projections in the UK are PA chest and lateral sternum. In the US, the two basic projections are a 15 to 20 degree Right Anterior Oblique and a Lateral.Sternoclavicular Joints - Are usually ordered as a single PA and a Right and Left 15 degree Right Anterior Obliques in the US.
|
What are the two major types of seed plants called?
|
[
"perennials and annuals",
"flowers and fruits",
"deciduous and evergreen",
"gymnosperms and angiosperms"
] |
D
|
The two major types of seed plants are the gymnosperms (seeds in cones) and angiosperms (seeds in ovaries of flowers). Figure below shows how the seeds of gymnosperms and angiosperms differ. Do you see the main difference between the two seeds? The angiosperm seed is surrounded by an ovary .
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).
Following the evolution of the seed habit, seed plants diversified, giving rise to a number of now-extinct groups, including seed ferns, as well as the modern gymnosperms and angiosperms. Gymnosperms produce "naked seeds" not fully enclosed in an ovary; modern representatives include conifers, cycads, Ginkgo, and Gnetales. Angiosperms produce seeds enclosed in a structure such as a carpel or an ovary. Ongoing research on the molecular phylogenetics of living plants appears to show that the angiosperms are a sister clade to the gymnosperms.
In some species, however, the pappus falls off (for example in Helianthus). Cypsela morphology is often used to help determine plant relationships at the genus and species level. The mature seeds usually have little endosperm or none.
seed texture (round vs wrinkled) seed color (yellow vs green) flower color (white vs purple) growth habit (tall vs dwarf) pod shape (pinched or inflated) pod color (green vs yellow) flower position (axial or terminal). Peas are normally self-pollinated because the stamens and carpels are enclosed within the petals. By removing the stamens from unripe flowers, Mendel could brush pollen from another variety on the carpels when they ripened.
The key activities of cultivated plant taxonomy relate to classification (taxonomy) and naming (nomenclature). The rules associated with naming plants are separate from the methods, principles or purposes of classification, except that the units of classification, the taxa, are placed in a nested hierarchy of ranks – like species within genera, and genera within families. There are three classification categories used in the Cultivated Plant Code, the cultivar and the Group and the grex, but they are only loosely equivalent to ranks in the Botanical Code.From the time of the ancient world, at least, plants have been classified in two ways. On the one hand there is the detached academic, philosophical or scientific interest in plants themselves: this groups plants by their relationship to one another according to their similarities and differences in structure and function.
|
What do we call the energy-rich product of photosynthesis?
|
[
"chloride",
"sugar",
"glucose",
"insulin"
] |
C
|
Glucose is the energy-rich product of photosynthesis, a universal food for life. It is also the primary form in which your bloodstream delivers energy to every cell in your body.
During photosynthesis, primary producers take energy from the sun and convert it into energy, sugar, and oxygen. Primary producers also need the energy to convert this same energy elsewhere, so they get it from nutrients. One type of nutrient is nitrogen.
Primary production is the production of chemical energy in organic compounds by living organisms. The main source of this energy is sunlight but a minute fraction of primary production is driven by lithotrophic organisms using the chemical energy of inorganic molecules.Regardless of its source, this energy is used to synthesize complex organic molecules from simpler inorganic compounds such as carbon dioxide (CO2) and water (H2O). The following two equations are simplified representations of photosynthesis (top) and (one form of) chemosynthesis (bottom): CO2 + H2O + light → CH2O + O2 CO2 + O2 + 4 H2S → CH2O + 4 S + 3 H2OIn both cases, the end point is a polymer of reduced carbohydrate, (CH2O)n, typically molecules such as glucose or other sugars. These relatively simple molecules may be then used to further synthesise more complicated molecules, including proteins, complex carbohydrates, lipids, and nucleic acids, or be respired to perform work. Consumption of primary producers by heterotrophic organisms, such as animals, then transfers these organic molecules (and the energy stored within them) up the food web, fueling all of the Earth's living systems.
Primary production is the process by which autotrophs use light to convert carbon from aqueous carbon dioxide to sugar for cellular growth. Light provides the energy for the photosynthetic process and nutrients are incorporated into organic material. For photosynthesis to occur, macronutrients such as nitrate and phosphate must be available in sufficient ratios and bioavailable forms for biological utilization. The molecular ratio of 106(Carbon):16(Nitrogen):1(Phosphorus) was deduced by Redfield, Ketcham, and Richards (RKR) and is known as the Redfield Ratio.
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.
Photosynthesis, however, is often low at the top few millimeters of the surface, likely due to inhibition by ultraviolet light. The exact depth and photosynthetic rate measurements of this curve are system specific and depend upon: 1) the total biomass of photosynthesizing cells, 2) the amount of light attenuating materials and 3) the abundance and frequency range of light absorbing pigments (i.e. chlorophylls) inside of photosynthesizing cells. The energy created by these primary producers is important for the community because it is transferred to higher trophic levels via consumption.
|
How is oxygen transferred into the bloodstream?
|
[
"mean diffusion",
"hard diffusion",
"brain diffusion",
"simple diffusion"
] |
D
|
The oxygen enters the bloodstream from the alveoli , tiny sacs in the lungs where gas exchange takes place ( Figure below ). The transfer of oxygen into the blood is through simple diffusion.
Blood flows on the outside of the hollow fibers, while oxygen flows in the opposite direction on the inside of the fibers. As the blood passes through the oxygenator, the blood comes into intimate contact with the fine surfaces of the device itself. Gas containing oxygen and medical air is delivered to the interface between the blood and the device, permitting the blood cells to absorb oxygen molecules directly.
To provide a simplified synopsis of the molecular mechanism of systemic gas exchange in layman's terms, upon inhalation of air it was widely thought oxygen binding to any of the heme sites triggers a conformational change in the globin/protein unit of hemoglobin which then enables the binding of additional oxygen to each of the other vacant heme sites. Upon arrival to the cell/tissues, oxygen release into the tissue is driven by "acidification" of the local pH (meaning a relatively higher concentration of 'acidic' protons/hydrogen ions) caused by an increase in the biotransformation of carbon dioxide waste into carbonic acid via carbonic anhydrase. In other words, oxygenated arterial blood arrives at cells in the "hemoglobin R-state" which has deprotonated/unionized amino acid residues (regarding nitrogen/amines) due to the less-acidic arterial pH environment (arterial blood averages pH 7.407 whereas venous blood is slightly more acidic at pH 7.371).
One of the main roles of extracellular fluid is to facilitate the exchange of molecular oxygen from blood to tissue cells and for carbon dioxide, CO2, produced in cell mitochondria, back to the blood. Since carbon dioxide is about 20 times more soluble in water than oxygen, it can relatively easily diffuse in the aqueous fluid between cells and blood.However, hydrophobic molecular oxygen has very poor water solubility and prefers hydrophobic lipid crystalline structures. As a result of this, plasma lipoproteins can carry significantly more O2 than in the surrounding aqueous medium.If hemoglobin in erythrocytes is the main transporter of oxygen in the blood, plasma lipoproteins may be its only carrier in the ECF.
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.
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.
|
Ringworm and athlete's foot are human diseases caused by what simple organisms?
|
[
"bacteria",
"insects",
"viruses",
"fungi"
] |
D
|
Fungi are simple eukaryotic organisms that consist of one or more cells. They include mushrooms and yeasts. Human diseases caused by fungi include ringworm and athlete’s foot. Both are skin diseases that are not usually serious. A ringworm infection is pictured below ( Figure below ). A more serious fungus disease is histoplasmosis. It is a lung infection. Though fungal infections can be annoying, they are rarely as serious or deadly as bacterial or viral infections.
Furthermore, persons with immuno-deficiencies are particularly susceptible to disease by genera such as Aspergillus, Candida, Cryptoccocus, Histoplasma, and Pneumocystis. Other fungi can attack eyes, nails, hair, and especially skin, the so-called dermatophytic and keratinophilic fungi, and cause local infections such as ringworm and athlete's foot. Fungal spores are also a cause of allergies, and fungi from different taxonomic groups can evoke allergic reactions.
The most common term for the infection, "ringworm", is a misnomer, since the condition is caused by fungi of several different species and not by parasitic worms.
The second stage of the disease is marked by the invasion of the foot by the foot rot bacterium Dichelobacter nodosus, a Gram-negative anaerobe. Usually, an injury to the skin between the hooves allows the bacteria to infect the animal. Another cause of foot rot may be high temperatures or humidity, causing the skin between the hooves to crack and let the bacteria infect the foot.
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).
Foot rot, also known as foul-in-the-foot, interdigital necrobacillosis or infectious pododermatitis, is a hoof infection commonly found in sheep, goats, and cattle. As the name suggests, it rots away the foot of the animal, more specifically the area between the two toes of the affected animal. It is extremely painful and contagious. It can be treated with a series of medications, but if not treated, the whole herd can become infected.
|
What is the measure of the change in the velocity of a moving object called?
|
[
"transmission",
"compression",
"acceleration",
"pressurization"
] |
C
|
A car’s gas pedal, like the one in Figure below , is sometimes called the accelerator. That’s because it controls the acceleration of the car. Pressing down on the gas pedal gives the car more gas and causes the car to speed up. Letting up on the gas pedal gives the car less gas and causes the car to slow down. Whenever an object speeds up, slows down, or changes direction, it accelerates. Acceleration is a measure of the change in velocity of a moving object. Acceleration occurs whenever an object is acted upon by an unbalanced force.
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} .
For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an acceleration.Viscometer – (also called viscosimeter) is an instrument used to measure the viscosity of a fluid. For liquids with viscosities which vary with flow conditions, an instrument called a rheometer is used.
Motion and change are closely related in Aristotelian physics. Motion, according to Aristotle, involved a change from potentiality to actuality. He gave example of four types of change, namely change in substance, in quality, in quantity and in place.
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.
Change in angular displacement per unit time is called angular velocity with direction along the axis of rotation. The symbol for angular velocity is ω {\displaystyle \omega } and the units are typically rad s−1. Angular speed is the magnitude of angular velocity. The instantaneous angular velocity is given by Using the formula for angular position and letting v = d s d t {\displaystyle v={\frac {ds}{dt}}} , we have also where v {\displaystyle v} is the translational speed of the particle. Angular velocity and frequency are related by
|
What is the usual treatment for acute bronchitis?
|
[
"surgery",
"antibiotics",
"physical therapy",
"pesticides"
] |
B
|
Bronchitis is an inflammation of the bronchi, the air passages that conduct air into the lungs. The bronchi become red and swollen with infection. Acute bronchitis is usually caused by viruses or bacteria, and may last several days or weeks. It is characterized by a cough that produces phlegm, or mucus. Symptoms include shortness of breath and wheezing. Acute bronchitis is usually treated with antibiotics.
A physical examination will often reveal decreased intensity of breath sounds, wheezing, rhonchi, and prolonged expiration. During examination for physicians rely on history and the presence of persistent or acute onset of cough, followed by a URTI with no traces of pneumonia. Acute bronchitis is typically a clinical diagnosis that relies on patients history and exam, and should be suspected in patients with an acute onset of cough, which often follows a URTI without traces of pneumonia.Although there is no universally-accepted clinical definition for acute bronchitis, there is a proposed set of practical criteria (Macfarlane, 2001) that include: An acute illness of less than three weeks. Cough as the predominant symptom.
If signs of dehydration are present, fluids may also be given orally or through an IV.Additional supportive treatments have been investigated in infants hospitalized with RSV bronchiolitis. These include: Nebulized hypertonic saline has been shown to reduce length of hospitalization and reduce clinical severity in infants with viral bronchiolitis. A possible mechanism is reduced airway edema and mucus plugging to decrease airway obstruction.
The primary prevention of bronchiolitis obliterans in people who have received either lung transplant or HSCT therapy is immunosuppression. In regards to post lung transplantation, the combination of calcineurin inhibitor combined with a purine synthesis inhibitor and a glucocorticoid is the general regimen used. People also have a baseline post-transplant lung function testing done in order to determine if their lung function is declining over time. People who are post-HSCT their immunosuppressive regimen typically includes methotrexate in combination with a calcineurin inhibitor to prevent GVHD, a risk factor for developing bronchiolitis obliterans.
That's the very best preventative I can recommend." The use of ventilators for COVID-19 treatment was misguided, and that patients "needed antibiotics" instead. The coronavirus was man-made but was accidentally released.
Acute exacerbations can be partially prevented. Some infections can be prevented by vaccination against pathogens such as influenza and Streptococcus pneumoniae. Regular medication use can prevent some COPD exacerbations; long acting beta-adrenoceptor agonists (LABAs), long-acting anticholinergics, inhaled corticosteroids and low-dose theophylline have all been shown to reduce the frequency of COPD exacerbations. Other methods of prevention include: Smoking cessation and avoiding dust, passive smoking, and other inhaled irritants Yearly influenza and 5-year pneumococcal vaccinations Regular exercise, appropriate rest, and healthy nutrition Avoiding people currently infected with e.g. cold and influenza Maintaining good fluid intake and humidifying the home, in order to help reduce the formation of thick sputum and chest congestion.
|
What are generally divided into prosimian and non-prosimian?
|
[
"primates",
"carnivores",
"rodents",
"insects"
] |
A
|
Primates are generally divided into prosimian and non-prosimian primates.
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).
The following are examples of application of the nomenclature.
There are typically three types of nonunion described.
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.
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.
|
The creation and destruction of oceanic crust is the reason what moves?
|
[
"animals",
"planets",
"continents",
"oceans"
] |
C
|
In some places, the oceanic crust comes up to a continent. The moving crust pushes that continent away from the ridge axis as well. If the moving oceanic crust reaches a deep sea trench, the crust sinks into the mantle. The creation and destruction of oceanic crust is the reason that continents move.
At subduction zones the relatively cold, dense oceanic crust sinks down into the mantle forming the downward convecting limb of a mantle cell. This is the strongest driver of the plates. The relative importance of other proposed factors such as active convection, upwelling and flow inside the mantle, and tidal drag of the moon, and their relationship to each other is still the subject of debate.
Seafloor spreading on mid-ocean ridges is a global scale ion-exchange system. Hydrothermal vents at spreading centers introduce various amounts of iron, sulfur, manganese, silicon, and other elements into the ocean, some of which are recycled into the ocean crust. Helium-3, an isotope that accompanies volcanism from the mantle, is emitted by hydrothermal vents and can be detected in plumes within the ocean.Fast spreading rates will expand the mid-ocean ridge causing basalt reactions with seawater to happen more rapidly. The magnesium/calcium ratio will be lower because more magnesium ions are being removed from seawater and consumed by the rock, and more calcium ions are being removed from the rock and released into seawater.
However, the formation process through detachment faults hypothesis has its limitations, such as the scarce seismic evidence that low-angle normal faulting exists, where the presumably significant offset along such faults - which transect the lithosphere at a low angle - should be involved with some friction. The rarity of eclogite in oceanic core complexes also casts doubt on the likelihood of a deep source in such domains. The abundance of peridotites in oceanic core complexes could be accounted for by a unique variation of ocean-ocean subduction at the junction of slow-spreading oceanic ridges and fracture zones.
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.
Evidence of this motion can be found in paleomagnetic striping on the seafloor. A paper written by geophysicist Taras Gerya theorizes that the creation of the transform faults between the ridges of the mid-oceanic ridge is attributed to rotated and stretched sections of the mid-oceanic ridge.
|
What is the concept by which two species within the same area to coexist by adapting by developing different specializations?
|
[
"character development",
"feature displacement",
"character concept",
"character displacement"
] |
D
|
Looking at different types of competition, ecologists developed the competitive exclusion principle . The principle states that species less suited to compete for resources will either adapt, move from the area, or die out. In order for two species within the same area to coexist, they may adapt by developing different specializations. This is known as character displacement . An example of character displacement is when different birds adapt to eating different types of food. They can develop different types of bills, like Darwin’s Finches ( Figure below ). Therefore, competition for resources within and between species plays an important role in evolution through natural selection .
In ecology, niche differentiation (also known as niche segregation, niche separation and niche partitioning) refers to the process by which competing species use the environment differently in a way that helps them to coexist. The competitive exclusion principle states that if two species with identical niches (ecological roles) compete, then one will inevitably drive the other to extinction. This rule also states that two species cannot occupy the same exact niche in a habitat and coexist together, at least in a stable manner. When two species differentiate their niches, they tend to compete less strongly, and are thus more likely to coexist.
It is also important to know that this type of natural selection is similar to the other ones. Where it is not the major factor, intraspecific competition can be discounted in assessing the operative aspects of the course of adaptation.
This postulate, however, can be misguided, as it ignores the impacts that the resources of each category have on the organism and the impacts that the organism has on the resources of each category. For instance, the resource in the overlap region can be non-limiting, in which case there is no competition for this resource despite niche overlap. An organism free of interference from other species could use the full range of conditions (biotic and abiotic) and resources in which it could survive and reproduce which is called its fundamental niche.
By incorporating specific information on a species' diet, reproduction, dispersal and habitat specialisation Verberk et al. could successfully explain the contribution of individual species to the overall relationship and they showed that the main mechanisms in operation may be different for different species groups. Neutral dynamics may be relatively important in some cases, depending on the species, environmental conditions and the spatial and temporal scale level under consideration, whereas in other circumstances, niche dynamics may dominate. Thus niche and neutral dynamics may be operating simultaneously, constituting different endpoints of the same continuum.
Specialization is also unique in the fact that it is a positive rather than neutral mutation process. When a gene specializes among different tissues, developmental stages, or environmental conditions it acquires an improvement in function. Isozymes are a good example of this because they are gene products of paralogs that catalyze the same biochemical reaction. However, different members have evolved particular adaptations to different tissues or different developmental stages that enhance the physiological fine-tuning of the cell.
|
A turbine that spins a generator will produce?
|
[
"electricity",
"solar energy",
"light",
"magnetic fields"
] |
A
|
You can follow the operation of an electricity-generating fission reactor in the image above. The reactor core is submerged in a pool of water. The heat from the fission reaction heats the water, which is pumped into a heat exchange container. There the heated water boils the water in the heat exchanger. The produced steam is forced through a turbine that spins a generator and produces electricity. After the water passes through the turbine, it is condensed back to liquid water and pumped back to the heat exchanger.
The Turbine converts dynamic pressure or kinetic energy to mechanical rotation and thereby to electrical power using a generator. The device has been constructed and tested, but has been criticized for lack of efficiency. As of 2017, prototypes are being installed.
A turbine ( or ) (from the Greek τύρβη, tyrbē, or Latin turbo, meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical power when combined with a generator. A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor.
The generator, typically about 30 feet (9 m) long and 12 feet (3.7 m) in diameter, contains a stationary stator and a spinning rotor, each containing miles of heavy copper conductor. There is generally no permanent magnet, thus preventing black starts. In operation it generates up to 21,000 amperes at 24,000 volts AC (504 MWe) as it spins at either 3,000 or 3,600 rpm, synchronized to the power grid. The rotor spins in a sealed chamber cooled with hydrogen gas, selected because it has the highest known heat transfer coefficient of any gas and for its low viscosity, which reduces windage losses.
The desired frequency affects the design of large turbines, since they are highly optimized for one particular speed. The electricity flows to a distribution yard where transformers increase the voltage for transmission to its destination. The steam turbine-driven generators have auxiliary systems enabling them to work satisfactorily and safely.
The turbine and the generator rotors are mounted on the same shaft. The combined weight of the rotors is almost 200 t (220 short tons) and their nominal rotational speed is 3000 rpm.The turbogenerator is 39 m (127 ft 11 in) long and its total weight is 1,200 t (1,300 short tons). The coolant flow for each turbine is 82,880 t (91,360 short tons)/h.
|
Meiosis in the sporophyte produces haploid cells called what?
|
[
"fibers",
"ions",
"spores",
"seeds"
] |
C
|
Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis; the sporophyte generation is diploid and produces spores by meiosis. Polyploidy may occur due to abnormal cell division, either during mitosis, or more commonly from the failure of chromosomes to separate during meiosis or from the fertilization of an egg by more than one sperm.
The sporophyte develops from the zygote produced when a haploid egg cell is fertilized by a haploid sperm and each sporophyte cell therefore has a double set of chromosomes, one set from each parent. All land plants, and most multicellular algae, have life cycles in which a multicellular diploid sporophyte phase alternates with a multicellular haploid gametophyte phase. In the seed plants, the largest groups of which are the gymnosperms and flowering plants (angiosperms), the sporophyte phase is more prominent than the gametophyte, and is the familiar green plant with its roots, stem, leaves and cones or flowers. In flowering plants the gametophytes are very reduced in size, and are represented by the germinated pollen and the embryo sac.
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.
Meiosis only occurs in cells of the sex organs, and serves the purpose of generating haploid gametes such as sperm, eggs, or spores, which are later fused during fertilization. The two meiotic divisions, known as Meiosis I and Meiosis II, may also include various genetic recombination events between homologous chromosomes. meiotic spindle See spindle apparatus.
Reproductive spores are generally the result of cell division, most commonly meiosis (e.g. in plant sporophytes). Sporic meiosis is needed to complete the sexual life cycle of the organisms using it. In some cases, sporogenesis occurs via mitosis (e.g. in some fungi and algae). Mitotic sporogenesis is a form of asexual reproduction.
|
In this type of reaction, an element replaces another element in a compound, and the element is in any state of matter but is not an ion?
|
[
"double-replacement reaction",
"replication reaction",
"single-replacement reaction",
"polar reaction"
] |
C
|
A single-replacement reaction is one in which an element replaces another element in a compound. An element is in either the solid, liquid, or gas state and is not an ion. The example below shows the reaction of solid magnesium metal with aqueous silver nitrate to form aqueous magnesium nitrate and silver metal.
Some reactions considered fundamental to the behavior of metal aquo ions are ligand exchange, electron-transfer, and acid-base reactions.
The matrix is then thought to transfer protons to the analyte molecules (e.g., protein molecules), thus charging the analyte. An ion observed after this process will consist of the initial neutral molecule with ions added or removed. This is called a quasimolecular ion, for example + in the case of an added proton, + in the case of an added sodium ion, or − in the case of a removed proton.
There are some types of combination reactions (a) Combination reactions between two elements. (b) Combination reactions between two compounds. (c) Combination reactions between an element and a compound.
The phrase -ate ion or ate ion can refer generically to many negatively charged anions. -ate compound or ate compound can refer to salts of the anions or esters of the functional groups. Chemical terms ending in -ate (and -ite) generally refer to the negatively charged anions, neutral radicals, and covalently bonded functional groups that share the same chemical formulas (with different charges). For example, the nitrate anion, NO−3; the nitrate functional group that forms nitrate esters, −NO3 or −ONO2; and the nitrate radical or nitrogen trioxide, •NO3.
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.
|
What are the two distinct types of cells found in the animal kingdom?
|
[
"DNA and Eukaryotes",
"bacteria and eukaryotes",
"prokaryotes and eukaryotes",
"chromosomes and eukaryotes"
] |
C
|
It contains numerous granulosa cells.
For example, erythrocytes, macrophages and plasma cells are produced in the anterior kidney (or pronephros) and some areas of the gut (where granulocytes mature.) They resemble primitive bone marrow in hagfish. Cartilaginous fish (sharks and rays) have a more advanced immune system.
There are two types of cells: prokaryotes and eukaryotes. Prokaryotes were the first of the two to develop and do not have a self-contained nucleus. Their mechanisms are simpler than later-evolved eukaryotes, which contain a nucleus that envelops the cell's DNA and some organelles.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a relatively flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible. This may be calcified, forming structures such as shells, bones, and spicules. In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth.
Most protists are single-celled and microscopic. But there are exceptions. Some single-celled marine protists are macroscopic.
|
What category of elements are chacterized by their ability to reflect light, called luster, their high electrical and thermal conductivity, their high heat capacity, and their malleability and ductility?
|
[
"metals",
"halogens",
"nonmetals",
"noble gases"
] |
A
|
Metallic Solids Metals are characterized by their ability to reflect light, called luster, their high electrical and thermal conductivity, their high heat capacity, and their malleability and ductility. Every lattice point in a pure metallic element is occupied by an atom of the same metal. The packing efficiency in metallic crystals tends to be high, so the resulting metallic solids are dense, with each atom having as many as 12 nearest neighbors. Bonding in metallic solids is quite different from the bonding in the other kinds of solids we have discussed. Because all the atoms are the same, there can be no ionic bonding, yet metals always contain too few electrons or valence orbitals to form covalent bonds with each of their neighbors. Instead, the valence electrons are delocalized throughout the crystal, providing a strong cohesive force that holds the metal atoms together.
Materials can be compared and categorized by any quantitative measure of their behavior under various conditions. Notable additional properties include the optical, electrical, and magnetic behavior of materials. : 5–7
Several terms are commonly used to characterize the general physical and chemical properties of the chemical elements. A first distinction is between metals, which readily conduct electricity, nonmetals, which do not, and a small group, (the metalloids), having intermediate properties and often behaving as semiconductors. A more refined classification is often shown in colored presentations of the periodic table. This system restricts the terms "metal" and "nonmetal" to only certain of the more broadly defined metals and nonmetals, adding additional terms for certain sets of the more broadly viewed metals and nonmetals.
Those closer to the left side of the periodic table, or further down a column, often have some weak metallic interactions between their molecules, chains, or layers, consistent with their proximity to the metals; this occurs in boron, carbon, phosphorus, arsenic, selenium, antimony, tellurium and iodine.Nonmetallic elements are either shiny, colored, or colorless. The shiny appearance of boron, graphitic carbon, silicon, black phosphorus, germanium, arsenic, selenium, antimony, tellurium, and iodine is a result of their structures featuring varying degrees of delocalized (free-moving) electrons that scatter incoming visible light. The colored nonmetals (sulfur, fluorine, chlorine, bromine) absorb some colors (wavelengths) and transmit the complementary or opposite colors.
The heat transfer by radiation is proportional to the power of four of the absolute surface temperature. The emissivity of a material (usually written ε or e) is the relative ability of its surface to emit energy by radiation. A black body has an emissivity of 1 and a perfect reflector has an emissivity of 0.In radiative heat transfer, a view factor quantifies the relative importance of the radiation that leaves an object (person or surface) and strikes another one, considering the other surrounding objects.
Like radio and microwave, infrared (IR) also is reflected by metals (and also most EMR, well into the ultraviolet range). However, unlike lower-frequency radio and microwave radiation, Infrared EMR commonly interacts with dipoles present in single molecules, which change as atoms vibrate at the ends of a single chemical bond. It is consequently absorbed by a wide range of substances, causing them to increase in temperature as the vibrations dissipate as heat.
|
Angiosperms are also known as what?
|
[
"dry plants",
"uncommon plants",
"dead plants",
"flowering plants"
] |
D
|
Introduction Plants are as essential to human existence as land, water, and air. Without plants, our day-to-day lives would be impossible because without oxygen from photosynthesis, aerobic life cannot be sustained. From providing food and shelter to serving as a source of medicines, oils, perfumes, and industrial products, plants provide humans with numerous valuable resources. When you think of plants, most of the organisms that come to mind are vascular plants. These plants have tissues that conduct food and water, and they have seeds. Seed plants are divided into gymnosperms and angiosperms. Gymnosperms include the needle-leaved conifers—spruce, fir, and pine—as well as less familiar plants, such as ginkgos and cycads. Their seeds are not enclosed by a fleshy fruit. Angiosperms, also called flowering plants, constitute the majority of seed plants. They include broadleaved trees (such as maple, oak, and elm), vegetables (such as potatoes, lettuce, and carrots), grasses, and plants known for the beauty of their flowers (roses, irises, and daffodils, for example). While individual plant species are unique, all share a common structure: a plant body consisting of stems, roots, and leaves. They all transport water, minerals, and sugars produced through photosynthesis through the plant body in a similar manner. All plant species also respond to environmental factors, such as light, gravity, competition, temperature, and predation.
Angiosperms were formerly called Magnoliophyta ().Angiosperms are distinguished from the other seed-producing plants, the gymnosperms, by having flowers, xylem consisting of vessel elements instead of tracheids, endosperm within their seeds, and fruits that completely envelop the seeds. The ancestors of flowering plants diverged from the common ancestor of all living gymnosperms before the end of the Carboniferous, over 300 million years ago. In the Cretaceous, angiosperms diversified explosively, becoming the dominant group of plants across the planet.
Following the evolution of the seed habit, seed plants diversified, giving rise to a number of now-extinct groups, including seed ferns, as well as the modern gymnosperms and angiosperms. Gymnosperms produce "naked seeds" not fully enclosed in an ovary; modern representatives include conifers, cycads, Ginkgo, and Gnetales. Angiosperms produce seeds enclosed in a structure such as a carpel or an ovary. Ongoing research on the molecular phylogenetics of living plants appears to show that the angiosperms are a sister clade to the gymnosperms.
The APG IV system of flowering plant classification is the fourth version of a modern, mostly molecular-based, system of plant taxonomy for flowering plants (angiosperms) being developed by the Angiosperm Phylogeny Group (APG). It was published in 2016, seven years after its predecessor the APG III system was published in 2009, and 18 years after the first APG system was published in 1998. In 2009, a linear arrangement of the system was published separately; the APG IV paper includes such an arrangement, cross-referenced to the 2009 one.Compared to the APG III system, the APG IV system recognizes five new orders (Boraginales, Dilleniales, Icacinales, Metteniusales and Vahliales), along with some new families, making a total of 64 angiosperm orders and 416 families. In general, the authors describe their philosophy as "conservative", based on making changes from APG III only where "a well-supported need" has been demonstrated. This has sometimes resulted in placements that are not compatible with published studies, but where further research is needed before the classification can be changed.
Most marine mineral antioxidants act in the cells as essential trace elements in redox and antioxidant metalloenzymes.When plants and animals began to enter rivers and land about 500 Ma, environmental deficiency of these marine mineral antioxidants was a challenge to the evolution of terrestrial life. Terrestrial plants slowly optimized the production of new endogenous antioxidants such as ascorbic acid, polyphenols, flavonoids, tocopherols, etc. A few of these appeared more recently, in last 200–50 Ma, in fruits and flowers of angiosperm plants. In fact, angiosperms (the dominant type of plant today) and most of their antioxidant pigments evolved during the Late Jurassic period.
Although it is not the usual route of a microspore, this process is the most effective way of yielding haploid and double haploid plants through the use of male sex hormones. Under certain stressors such as heat or starvation, plants select for microspore embryogenesis. It was found that over 250 different species of angiosperms responded this way.
|
An estimated 100 trillion of these live in the gut of an average person?
|
[
"viruses",
"pathogens",
"bacteria",
"algae"
] |
C
|
It is estimated that 100 trillion bacteria live in the gut. This is more than the human cells that make up you. It has also been estimated that there are more bacteria in your mouth than people on the planet. There are over 7 billion people on the planet.
The upper-middle segment, consisting of adults with wealth between USD 100,000 and USD 1 million is projected to rise by 178 million adults. Most of these new members (approximately 114 million) are likely to come from upper-middle-income countries. Number of global millionaires is also projected to increase.
According to Chen and Ravallion, about 1.76 billion people in developing world lived above $1.25 per day and 1.9 billion people lived below $1.25 per day in 1981. In 2005, about 4.09 billion people in developing world lived above $1.25 per day and 1.4 billion people lived below $1.25 per day (both 1981 and 2005 data are on inflation adjusted basis). The share of the world's population living in absolute poverty fell from 43% in 1981 to 14% in 2011. The absolute number of people in poverty fell from 1.95 billion in 1981 to 1.01 billion in 2011.
An estimated 550,000 people live in the triangle of death. The annual death rate per 100,000 inhabitants from liver cancer is approximately 38.4 for men and 20.8 for women in this area, as compared to the national average of 14. The death rate for bladder cancer and cancer of the central nervous system was also higher than the national average. The high death rates from cancers pointed towards the presence of illegal and improper hazardous waste disposal by various organized crime groups including the Camorra.
This location suggests that these individuals belonged to a lower social stratum. Their results indicated no significant differences in δ13C and δ15N values which means that the individuals buried in the "healthy" regions and those buried in the "unhealthy" regions appeared to have had similar diets.In 2013, Kristina Killgrove, a classicist and bioarchaeologist, studied individuals from a medieval cemetery site in Berlin, Germany.
Today, the Growing Up Today Study team includes doctors, researchers, and statisticians throughout the United States, and GUTS data is used by researchers across the globe. Major research topics include: Diet & Nutrition Physical Activity Substance Use Eating Disorders Gender Sexual Orientation Genetics Environmental factors Women’s Health Disease Risk Economic/Work StatusNearly 100 research articles about health outcomes throughout a lifetime – from pregnancy and fertility to heart disease, hypertension, and diabetes—have been published as a result of their work and the continuous contributions of GUTS participants. More information can be found at http://www.gutsweb.org.
|
The ability to regulate what, which is possessed by mammals, was an advantage as earth’s climate went through sudden and dramatic changes?
|
[
"mutations",
"reflex behaviors",
"body temperature",
"hair growth"
] |
C
|
Mammals have the ability to regulate body temperature. This is an advantage, as Earth’s climate went through sudden and dramatic changes. Mastodons, saber tooth tigers, hoofed mammals, whales, primates and eventually humans all lived during the Cenozoic Era ( Figure below ).
In contrast, small mammals, with their shorter life cycles, shorter reproductive cycles, and shorter gestation periods, could have adjusted to the increased unpredictability of the climate, both as individuals and as species which allowed them to synchronize their reproductive efforts with conditions favorable for offspring survival. If so, smaller mammals would have lost fewer offspring and would have been better able to repeat the reproductive effort when circumstances once more favored offspring survival.In 2017 a study looked at the environmental conditions across Europe, Siberia and the Americas from 25,000–10,000 YBP. The study found that prolonged warming events leading to deglaciation and maximum rainfall occurred just prior to the transformation of the rangelands that supported megaherbivores into widespread wetlands that supported herbivore-resistant plants. The study proposes that moisture-driven environmental change led to the megafaunal extinctions and that Africa's trans-equatorial position allowed rangeland to continue to exist between the deserts and the central forests, therefore fewer megafauna species became extinct there.
Human Ecology 21(2):145-166. Hogbin, Ian, ed. 1973.
The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect was first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change Earth's energy balance and climate. Many other theories of climate change were advanced, involving forces from volcanism to solar variation.
Over the past 150 years human activities have released increasing quantities of greenhouse gases into the atmosphere. This has led to increases in mean global temperature, or global warming. Other human effects are relevant—for example, sulphate aerosols are believed to have a cooling effect. Natural factors also contribute.
Nutrient stress is likely to lead to stronger bite forces to more fully consume carcasses and to crack bones, and with changes to skull shape to improve mechanical advantage. North American climate records reveal cyclic fluctuations during the glacial period that included rapid warming followed by gradual cooling, called Dansgaard–Oeschger events. These cycles would have caused increased temperature and aridity, and at La Brea would have caused ecological stress and therefore food stress. A similar trend was found with the gray wolf, which in the Santa Barbara basin was originally massive, robust, and possibly convergent evolution with the dire wolf, but was replaced by more gracile forms by the start of the Holocene.
|
What is the term for very large arrays of tandemly repeating, non-coding dna?
|
[
"satellite dna",
"recombinant dna",
"models dna",
"addition dna"
] |
A
|
The majority of the human genome is non-coding sequence. These sequences include regulatory sequences, and DNA with unknown functions. These sequences include tandem repeat elements known as satellite DNA , and transposons. Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. The repeating units can be just a single base (a mono nucleotide repeat), two bases (a dinucleotide repeat), three bases (a trinucleotide repeat) or a much larger repeating unit. Some repeating units are several thousand base pairs long, and the total size of a satellite DNA segment can be several megabases without interruption.
tandem repeat A pattern within a nucleic acid sequence in which one or more nucleobases are repeated and the repetitions are directly adjacent (i.e. tandem) to each other. An example is ATGACATGACATGAC, in which the sequence ATGAC is repeated three times. TATA box Also Goldberg-Hogness box. A highly conserved non-coding DNA sequence containing a consensus of repeating T and A base pairs that is commonly found in promoter regions of genes in archaea and eukaryotes.
While tandem and interspersed repeats are distinguished based on their location in the genome, direct and inverted repeats are distinguished based on the ordering of the nucleotide bases. Direct repeats occur when a nucleotide sequence is repeated with the same directionality. Inverted repeats occur when a nucleotide sequence is repeated in the inverse direction. For example, a direct repeat of "CATCAT" would be another repetition of "CATCAT."
DNA is a long polymer made from repeating units called nucleotides. The structure of DNA is dynamic along its length, being capable of coiling into tight loops and other shapes. In all species it is composed of two helical chains, bound to each other by hydrogen bonds. Both chains are coiled around the same axis, and have the same pitch of 34 ångströms (3.4 nm).
Although these are the general groups that copy number variations are grouped into, the exact number of base pairs copy number variations affect depends on the specific loci of interest. Currently, using data from all reported copy number variations, the mean size of copy number variant is around 118kb, and the median is around 18kb.In terms of the structural architecture of copy number variations, research has suggested and defined hotspot regions in the genome where copy number variations are four times more enriched. These hotspot regions were defined to be regions containing long repeats that are 90–100% similar known as segmental duplications either tandem or interspersed and most importantly, these hotspot regions have an increased rate of chromosomal rearrangement.
short tandem repeat (STR) See microsatellite. short interspersed nuclear element (SINE) shotgun sequencing silencer A sequence or region of DNA that can be bound by a repressor, thereby blocking the transcription of a nearby gene. silent allele An allele that does not produce a detectable product.
|
What kind of map can show the features of the bottom of a body of water?
|
[
"topographic",
"bathymetric",
"basic",
"country"
] |
B
|
Oceanographers use bathymetric maps to show the features of the bottom of a body of water.
Sub-surface seabed classification is commonly referred to as sub-bottom profiling and is generally used for geological assessment of the sub-surface characteristics. Sub-bottom profiling can return information from tens to hundreds of meters below the seafloor, and is often used to complement reflection seismology. From sub-surface classifications, scientists and engineers can characterize rock and sediment types, as well as pore fluids. This information is used for many applications, such as slope failure analysis and hydrocarbon exploration.
Another form of mapping the seafloor is through the use of satellites. The satellites are equipped with hyper-spectral and multi-spectral sensors which are used to provide constant streams of images of coastal areas providing a more feasible method of visualising the bottom of the seabed.
map A picture of a place drawn at an established scale on a two-dimensional plane surface, often depicting natural and manmade features on or under the surface of the Earth or other planetary body, typically with the features positioned as accurately as possible relative to a coordinate reference system; more generally, any graphical representation of locative information about the relative positions of particular features within a space or place. map index Also index map. A graphical key identifying the relationships between the individual maps of a map series, their coverage areas, and/or their production status or availability.
As with oceans, the benthic zone is the floor of the lake, composed of accumulated sunken organic matter. The littoral zone is the zone bordering the shore; light penetrates easily and aquatic plants thrive. The pelagic zone represents the broad mass of water, down as far as the depth to which no light penetrates.
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.
|
What evolved, adapted response to resource availability is the long-range seasonal movement of animals?
|
[
"changing",
"migration",
"Stagnation",
"regulating"
] |
B
|
Migration Migration is the long-range seasonal movement of animals. It is an evolved, adapted response to variation in resource availability, and it is a common phenomenon found in all major groups of animals. Birds fly south for the winter to get to warmer climates with sufficient food, and salmon migrate to their spawning grounds. The popular 2005 documentary March of the Penguins followed the 62-mile migration of emperor penguins through Antarctica to bring food back to their breeding site and to their young. Wildebeests (Figure 45.35) migrate over 1800 miles each year in search of new grasslands.
Seasons vary geographically. By migrating away from the equator, herbivores could have found areas with growing seasons more favorable for finding food and breeding successfully. Modern-day African elephants migrate during periods of drought to places where there is apt to be water.
It is thought to have originally evolved in three stages. The first is development of neuroendocrine control over bodily functions, the second is pairing of that to environmental changes—in this case metabolic rates decreasing in response to colder temperatures—and the third is the pairing of these controls with reliable seasonal indicators within the arthropod, like biological timers. From these steps, arthropods developed a seasonal diapause, where many of their biological functions end up paired with a seasonal rhythm within the organism. This is a very similar mechanism to the evolution of insect migration, where instead of bodily functions like metabolism getting paired with seasonal indicators, movement patterns would be paired with seasonal indicators.
To be counted as a true migration, and not just a local dispersal or irruption, the movement of the animals should be an annual or seasonal occurrence, or a major habitat change as part of their life. An annual event could include Northern Hemisphere birds migrating south for the winter, or wildebeest migrating annually for seasonal grazing. A major habitat change could include young Atlantic salmon or sea lamprey leaving the river of their birth when they have reached a few inches in size.
In terrestrial habitats they are subjected to daily and seasonal variation in temperature and water availability. Their success in colonizing different habitats is due to physiological, behavioral, and morphological adaptations to water availability, as well as ionic and thermal balance. They are adapted to most of the habitats on Earth.
A related phenomenon, known as demographic compensation, arises when the different components of species life cycles (survival, growth, fecundity, etc.) show negative correlations across the distribution ranges. For example, survival may be higher towards the northern edge of the distribution, while fecundity or growth increases towards the south, leading to a compensation that allows the species to persist along an environmental gradient. Contrasting trends in life cycle components may arise through tradeoffs in resource allocation, but also through independent but opposite responses to environmental conditions.
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