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What causes the particles of medium to move parallel to the direction of the wave?
|
[
"longitudinal waves",
"mechanical waves",
"fluid waves",
"Sound waves."
] |
A
|
Longitudinal waves cause the particles of medium to move parallel to the direction of the wave.
Motion of the medium itself. If the medium is moving, this movement may increase or decrease the absolute speed of the sound wave depending on the direction of the movement. For example, sound moving through wind will have its speed of propagation increased by the speed of the wind if the sound and wind are moving in the same direction.
The motion of transverse waves, on the other hand, is perpendicular to the propagation direction and is thus less easily propagated through the medium. As a result, longitudinal waves travel more quickly through solids than transverse waves. An example of this can be seen in quartz with an approximate acoustic longitudinal wave velocity of 5965 m/s and transverse wave velocity of 3750 m/s.
Wave drag (also called compressibility drag) is drag that is created when a body moves in a compressible fluid and at speeds that are close to the speed of sound in that fluid. In aerodynamics, wave drag consists of multiple components depending on the speed regime of the flight. In transonic flight (Mach numbers greater than about 0.8 and less than about 1.4), wave drag is the result of the formation of shockwaves in the fluid, formed when local areas of supersonic (Mach number greater than 1.0) flow are created. In practice, supersonic flow occurs on bodies traveling well below the speed of sound, as the local speed of air increases as it accelerates over the body to speeds above Mach 1.0.
Related early wave studies started in 1904 and progressed through more than half of the first part of the twentieth century. This early research included the relationship of the phase velocity to group velocity and the relationship of the wave vector and Pointing vector.In 1904 the possibility of negative phase velocity accompanied by an anti-parallel group velocity were noted by Horace Lamb (book: Hydrodynamics) and Arthur Schuster (Book: Intro to Optics). However both thought practical achievement of these phenomena were not possible.
Corrective waves subdivide into three smaller-degree waves starting with a five-wave counter-trend impulse, a retrace, and another impulse. In a bear market the dominant trend is downward, and the pattern is reversed—five waves down and three up. Motive waves always move with the trend, while corrective waves move against it.
|
Which state of matter lacks a fixed volume, fixed shape, and consists of charged particles?
|
[
"electrons",
"atoms",
"ions",
"isotopes"
] |
C
|
Plasma is a state of matter that lacks a fixed volume and a fixed shape and consists of charged particles called ions. Because it consists of charged particles, plasma can conduct electricity and respond to a magnetic field.
Nuclear matter is an idealized system of interacting nucleons (protons and neutrons) that exists in several phases of exotic matter that, as of yet, are not fully established. It is not matter in an atomic nucleus, but a hypothetical substance consisting of a huge number of protons and neutrons held together by only nuclear forces and no Coulomb forces. Volume and the number of particles are infinite, but the ratio is finite. Infinite volume implies no surface effects and translational invariance (only differences in position matter, not absolute positions).
In many cases, at fixed temperature and pressure, a substance can exist in several distinct states of matter in what might be viewed as the same 'body'. For example, ice may float in a glass of water. Then the ice and the water are said to constitute two phases within the 'body'.
As heat is added to this substance it melts into a liquid at its melting point, boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized that they leave their parent atoms. Forms of matter that are not composed of molecules and are organized by different forces can also be considered different states of matter.
In liquid state theory, the 'excluded volume' of a molecule is the volume that is inaccessible to other molecules in the system as a result of the presence of the first molecule. The excluded volume of a hard sphere is eight times its volume—however, for a two-molecule system, this volume is distributed among the two particles, giving the conventional result of four times the volume; this is an important quantity in the Van der Waals equation of state. The calculation of the excluded volume for particles with non-spherical shapes is usually difficult, since it depends on the relative orientation of the particles. The distance of closest approach of hard ellipses and their excluded area has been recently considered.
Quark matter or QCD matter (quantum chromodynamic) refers to any of a number of hypothetical phases of matter whose degrees of freedom include quarks and gluons, of which the prominent example is quark-gluon plasma. Several series of conferences in 2019, 2020, and 2021 were devoted to this topic.Quarks are liberated into quark matter at extremely high temperatures and/or densities, and some of them are still only theoretical as they require conditions so extreme that they cannot be produced in any laboratory, especially not at equilibrium conditions. Under these extreme conditions, the familiar structure of matter, where the basic constituents are nuclei (consisting of nucleons which are bound states of quarks) and electrons, is disrupted. In quark matter it is more appropriate to treat the quarks themselves as the basic degrees of freedom.
|
What type of cell transmits electrical impulses in the nervous system?
|
[
"toxin cell",
"Large Cell",
"trace cell",
"nerve cell"
] |
D
|
cell that transmits electrical impulses in the nervous system; commonly called nerve cell.
The brain and the spinal cord are the essential components of the central nervous system and it is responsible for the integration of the signals received from the afferent nerves and initiates action. The nerve cells, known as neurons, carry impulses throughout the body and the nerve impulses are carried along the axon. These microscopic nerve fibers, where the action potential occurs, are protected by a white, fatty tissue that surrounds and insulates it, known as the myelin sheath. This insulation helps the axon of a nerve cell with the conduction and speed of the signal along the axon.
Transmission Cells that carry the pain signal up to the brain, and 2. Inhibitory Interneurons that impede transmission cell activity. Activation of transmission cells occurs from both excitatory small-diameter and excitatory large-diameter fibers.
Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.
Efferent nerve-fibers carry impulses out from the center to their endings. Most of these go to muscles and are therefore called motor impulses; some are secretory and enter glands; a portion are inhibitory, their function being to restrain secretion. Thus, nerves carry impulses outward and sensations inward.
The knee-jerk reflex is an example of such a monosynaptic reflex. The most extensive input to α-MNs is from local interneurons, which are the most numerous type of neuron in the spinal cord. Among their many roles, interneurons synapse on α-MNs to create more complex reflex circuitry. One type of interneuron is the Renshaw cell.
|
What is the force pushing a rocket called?
|
[
"momentum",
"friction",
"direction",
"thrust"
] |
D
|
Most halogens have a variety of important uses. A few are described in the Table below .
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordance with Newton's third law. Most rocket engines use the combustion of reactive chemicals to supply the necessary energy, but non-combusting forms such as cold gas thrusters and nuclear thermal rockets also exist. Vehicles propelled by rocket engines are commonly called rockets.
A rocket-assisted projectile (RAP) is a cannon, howitzer, mortar, or recoilless rifle round incorporating a rocket motor for independent propulsion. This gives the projectile greater speed and range than a non-assisted ballistic shell, which is propelled only by the gun's exploding charge. Some forms of rocket-assisted projectiles can be outfitted with a laser-guide for greater accuracy.
Some rocket designs impart energy to their propellants with external energy sources. For example, water rockets use a compressed gas, typically air, to force the water reaction mass out of the rocket.
The People's Republic of China have also used their accomplishment in space as a form of internal and external propaganda. The word rocket itself means firing arrow. The concept of rocketry was first developed in China during the 3rd century A.D.
A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in warfare and sports (for example, a thrown baseball, kicked football, fired bullet, shot arrow, stone released from catapult).In ballistics mathematical equations of motion are used to analyze projectile trajectories through launch, flight, and impact.
|
In headwater streams, what plant process is mostly attributed to algae that are growing on rocks?
|
[
"mitosis",
"symbiosis",
"photosynthesis",
"reproduction"
] |
C
|
Abiotic features of rivers and streams vary along the length of the river or stream. Streams begin at a point of origin referred to as source water. The source water is usually cold, low in nutrients, and clear. The channel (the width of the river or stream) is narrower here than at any other place along the length of the river or stream. Headwater streams are of necessity at a higher elevation than the mouth of the river and often originate in regions with steep grades leading to higher flow rates than lower elevation stretches of the river. Faster-moving water and the short distance from its origin results in minimal silt levels in headwater streams; therefore, the water is clear. Photosynthesis here is mostly attributed to algae that are growing on rocks; the swift current inhibits the growth of phytoplankton. Photosynthesis may be further reduced by tree cover reaching over the narrow stream. This shading also keeps temperatures lower. An additional input of energy can come from leaves or other organic material that falls into a river or stream from the trees and other plants that border the water. When the leaves decompose, the organic material and nutrients in the leaves are returned to the water. The leaves also support a food chain of invertebrates that eat them and are in turn eaten by predatory invertebrates and fish. Plants and animals have adapted to this fast-moving water. For instance, leeches (phylum Annelida) have elongated bodies and suckers on both ends. These suckers attach to the substrate, keeping the leech anchored in place. In temperate regions, freshwater trout species (phylum Chordata) may be an important predator in these fast-moving and colder river and streams.
This is a contrast to on land, where most primary production is performed by vascular plants. Algae ranges from single floating cells to attached seaweeds, while vascular plants are represented in the ocean by groups such as the seagrasses and the mangroves. Larger producers, such as seagrasses and seaweeds, are mostly confined to the littoral zone and shallow waters, where they attach to the underlying substrate and are still within the photic zone.
Water, carbon dioxide, minerals and light are all important factors in cultivation, and different algae have different requirements. The basic reaction for algae growth in water is carbon dioxide + light energy + water = glucose + oxygen + water. This is called autotrophic growth. It is also possible to grow certain types of algae without light, these types of algae consume sugars (such as glucose). This is known as heterotrophic growth.
In addition to natural processes, human activities strongly influence the chemical composition of aquatic systems and their water quality.Allochthonous sources of carbon or nutrients come from outside the aquatic system (such as plant and soil material). Carbon sources from within the system, such as algae and the microbial breakdown of aquatic particulate organic carbon, are autochthonous. In aquatic food webs, the portion of biomass derived from allochthonous material is then named "allochthony". In streams and small lakes, allochthonous sources of carbon are dominant while in large lakes and the ocean, autochthonous sources dominate.
In tropical regions in particular, plants and animals not only affect the weathering of rocks but are a source of sediment themselves. The shells and skeletons of many organisms are of calcium carbonate and when this is broken down it forms sediment, limestone and clay.
It feeds by scraping minute algae and grasping pieces of seaweeds. Each individual rests in the same place and wears a slight depression in the rock into which the shell fits exactly. It is hard to remove when attached to the rock with its foot (Edmunds, 1978).
|
What is the term that refers to stored chemical energy in organic matter or wastes?
|
[
"nuclear energy",
"potential energy",
"starch energy",
"biomass energy"
] |
D
|
The stored chemical energy in organic matter or wastes is called biomass energy. The organic matter may be trees or other plants, or it may be wastes from homes and industries. When biomass is burned, it produces thermal energy that can be used for heating homes, cooking, or generating electricity. Biomass—especially wood—is an important energy source in the poorer nations where most people can’t afford fossil fuels. However, burning biomass releases air pollution and contributes to global climate change. Biomass can be used to make ethanol, a fuel that is added to gasoline. Although ethanol releases less pollution than gasoline, large areas of land are needed to grow the plants needed to make it (see Figure below ). This reduces the amount of land available for food production.
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.
A portion of organic matter is not mineralized and instead decomposed into stable organic matter that is denominated "humus".The decomposition of organic compounds occurs at very different rates, depending on the nature of the compound. The ranking, from fast to slow rates, is: Sugars, starches, and simple proteins Proteins Hemicelluloses Cellulose Lignins and fatsThe reactions that occur can be included in one of 3 genera: Enzymatic oxidation that produces carbon dioxide, water, and heat.
Upgrading raw biomass to higher grade fuels can be achieved by different methods, broadly classified as thermal, chemical, or biochemical: Thermal conversion processes use heat as the dominant mechanism to upgrade biomass into a better and more practical fuel. The basic alternatives are torrefaction, pyrolysis, and gasification, these are separated mainly by the extent to which the chemical reactions involved are allowed to proceed (mainly controlled by the availability of oxygen and conversion temperature).Many chemical conversions are based on established coal-based processes, such as the Fischer-Tropsch synthesis. Like coal, biomass can be converted into multiple commodity chemicals.Biochemical processes have developed in nature to break down the molecules of which biomass is composed, and many of these can be harnessed. In most cases, microorganisms are used to perform the conversion. The processes are called anaerobic digestion, fermentation, and composting.
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.
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.
|
The process of photosynthesis ultimately gets powered by what kind of energy?
|
[
"biofuel",
"electricity",
"nonrenewable energy",
"light"
] |
D
|
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.
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.
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.
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.
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.
|
A binary molecular compound is a molecular compound that is composed of what?
|
[
"two elements",
"two atoms",
"four atoms",
"four elements"
] |
A
|
A binary molecular compound is a molecular compound that is composed of two elements. In general, the elements that combine to form binary molecular compounds are both nonmetals. This contrasts with ionic compounds, which usually involve bonds between metal ions and nonmetal ions. Because ionic charges cannot be used to name these compounds or to write their formulas, a different naming system must be used for molecular compounds. Another difference between ionic and molecular compounds is that two nonmetal atoms will frequently combine with one another in a variety of ratios. For example, nitrogen and oxygen combine to make several binary compounds, including NO, NO 2 , and N 2 O. Obviously they can’t all be called nitrogen oxide! How would someone know which one you were talking about? Each of the three compounds has very different properties and reactivity. A system to distinguish between compounds such as these is necessary.
They can be broken into two categories: homonuclear and heteronuclear. A homonuclear diatomic molecule is one composed of two atoms of the same element. Examples are H2, O2, and N2. A heteronuclear diatomic molecule is composed of two atoms of two different elements. Examples include CO, HCl, and NO.
The behavior of biologically derived computational systems such as these relies on the particular molecules that make up the system, which are primarily proteins but may also include DNA molecules. Nanobiotechnology provides the means to synthesize the multiple chemical components necessary to create such a system. The chemical nature of a protein is dictated by its sequence of amino acids—the chemical building blocks of proteins. This sequence is in turn dictated by a specific sequence of DNA nucleotides—the building blocks of DNA molecules.
Triatomic molecules are molecules composed of three atoms, of either the same or different chemical elements. Examples include H2O, CO2 (pictured), HCN, O3 (ozone) and NO2.
Compound particles are formed with at least one particle together with other words, including other particles. The commonly seen forms are: particle + verb (term. or cont. or -te form) particle + noun + particle noun + particleOther structures are rarer, though possible. A few examples:
Binary liquid is a type of chemical combination, which creates a special reaction or feature as a result of mixing two liquid chemicals, that are normally inert or have no function by themselves. A number of chemical products are produced as a result of mixing two chemicals as a binary liquid, such as plastic foams and some explosives.
|
Within the first 8 weeks of gestation, a developing embryo establishes the rudimentary structures of all of its organs and tissues from the ectoderm, mesoderm, and endoderm. this process is called what?
|
[
"abiogenesis",
"biosynthesis",
"parthenogenesis",
"organogenesis"
] |
D
|
Within the first 8 weeks of gestation, a developing embryo establishes the rudimentary structures of all of its organs and tissues from the ectoderm, mesoderm, and endoderm. This process is called organogenesis. Like the central nervous system, the heart also begins its development in the embryo as a tube-like structure, connected via capillaries to the chorionic villi. Cells of the primitive tube-shaped heart are capable of electrical conduction and contraction. The heart begins beating in the beginning of the fourth week, although it does not actually pump embryonic blood until a week later, when the oversized liver has begun producing red blood cells. (This is a temporary responsibility of the embryonic liver that the bone marrow will assume during fetal development. ) During weeks 4–5, the eye pits form, limb buds become apparent, and the rudiments of the pulmonary system are formed. During the sixth week, uncontrolled fetal limb movements begin to occur. The gastrointestinal system develops too rapidly for the embryonic abdomen to accommodate it, and the intestines temporarily loop into the umbilical cord. Paddle-shaped hands and feet develop fingers and toes by the process of apoptosis (programmed cell death), which causes the tissues between the fingers to disintegrate. By week 7, the facial structure is more complex and includes nostrils, outer ears, and lenses (Figure 28.15). By the eighth week, the head is nearly as large as the rest of the embryo’s body, and all major brain structures are in place. The external genitalia are apparent, but at this point, male and female embryos are indistinguishable. Bone begins to replace cartilage in the embryonic skeleton through the process of ossification. By the end of the embryonic period, the embryo is approximately 3 cm (1.2 in) from crown to rump and weighs approximately 8 g (0.25 oz).
After implantation, around the second to third week the developing embryo consists of three layers: endoderm, mesoderm and ectoderm. The first part of the ear to develop is the inner ear, which begins to form from the ectoderm around the 22nd day of the embryo's development. Specifically, the inner ear derives from two thickenings called otic placodes on either side of the head. Each otic placode recedes below the ectoderm, forms an otic pit and then an otic vesicle.
Human embryonic development, or human embryogenesis, is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell (ovum).
The first ten weeks of gestational age is the period of embryogenesis and together with the first three weeks of prenatal development make up the first trimester of pregnancy. From the 10th week of gestation (8th week of development), the developing embryo is called a fetus. All major structures are formed by this time, but they continue to grow and develop. Because the precursors of the organs are now formed, the fetus is not as sensitive to damage from environmental exposure as the embryo was. Instead, toxic exposure often causes physiological abnormalities or minor congenital malformation.
Pregnancy is the development of an embryo or fetus inside the womb of a female for the rough duration of 9 months or 40 weeks from the last menstrual period until birth. It is divided into three trimesters, each lasting for about 3 months. The 1st trimester is when the developing embryo becomes a fetus, organs start to develop, limbs grow, and facial features appear. The 2nd and 3rd trimesters are marked by a significant amount of growth and functional development of the body.
It will have divided on its journey to form a blastocyst that will implant itself into the lining of the uterus – the endometrium, where it will receive nutrients and develop into the embryo proper and later fetus for the duration of the pregnancy. In the human embryo, the uterus develops from the paramesonephric ducts which fuse into the single organ known as a simplex uterus.
|
What goes through different larval stages?
|
[
"octopuses",
"plants",
"sponges",
"crustaceans"
] |
D
|
Figure 28.41 All crustaceans go through different larval stages. Shown are (a) the nauplius larval stage of a tadpole shrimp, (b) the cypris larval stage of a barnacle, and (c) the zoea larval stage of a green crab. (credit a: modification of work by USGS; credit b: modification of work by Mª. Mingorance Rodríguez; credit c: modification of work by B. Kimmel based on original work by Ernst Haeckel).
The larval stage, or caterpillar, is characterized by a pinkish or yellowish-green body color with a dark brown head. The larval stage of the moth's life cycle is centered on food sources; during the last instar, these larvae are characterized by a movement towards a protected area to pupate. These caterpillars have the capacity to chew through plastic packaging and will often produce silk that loosely binds to food fragments. The pupal stage is generally observed as tiny cocoons that hang from the ceiling; these cocoons can also be found on walls, as well as near the food source. A female can lay over 200 eggs and will usually die after this process because adults Indianmeal moths do not eat.
The eggs are normally laid on surface water and go through three distinct larval stages. The larvae are usually found in still or stagnant water, like water reservoirs or liquid dung. Just before the pupation stage, the larvae leave their aquatic environment.
The hatched larvae undergo various moulting stages that allow them to incrementally reach adulthood. The length of these moulting stages is dependent on the individual's nutrition levels. Finally, once the larvae finish these stages it conducts its final growth moulting phase called ecdysis.
By waiting until the final larval instar, it ensures the spider will not decompose before the larva has fully developed. The larva has five instar stages before it pupates; no major morphological differences are noted between the first four instars, with the exception of size. At the conclusion of the final instar, the larva spins a durable silk cocoon, and emerges as an adult either later in the same season or overwinters, depending on the species and the time of year the larva pupates.
The false codling moth experiences four life stages; egg, larva, pupa and adult.
|
What is the major cause of chronic respiratory disease as well as cardiovascular disease and cancer?
|
[
"smoking",
"drinking",
"exercise",
"diet"
] |
A
|
Smoking is the major cause of chronic respiratory disease as well as cardiovascular disease and cancer. Exposure to tobacco smoke by smoking or by breathing air that contains tobacco smoke is the leading cause of preventable death in the United States. Regular smokers die about 10 years earlier than nonsmokers do. The Centers for Disease Control and Prevention (CDC) describes tobacco use as "the single most important preventable risk to human health in developed countries and an important cause of [early] death worldwide. " Simply stated: Stopping smoking can prevent many respiratory diseases.
Risk factors for lung disease include tobacco smoking and environmental dust. The underlying mechanism involves unblocked neutrophil elastase and buildup of abnormal A1AT in the liver. It is autosomal co-dominant, meaning that one defective allele tends to result in milder disease than two defective alleles.
Several types of conditions can potentially result in respiratory failure: Conditions that reduce the flow of air into and out of the lungs, including physical obstruction by foreign bodies or masses and reduced breathing due to drugs or changes to the chest. Conditions that impair the lungs' blood supply. These include thromboembolic conditions and conditions that reduce the output of the right heart, such as right heart failure and some myocardial infarctions.
In a few cases, only one cause exists: for example, the virus HHV-8 causes all Kaposi's sarcomas. However, with the help of cancer epidemiology techniques and information, it is possible to produce an estimate of a likely cause in many more situations. For example, lung cancer has several causes, including tobacco use and radon gas.
This is an increase from the year 2000, during which 60% of deaths were attributed to these diseases.Preventive healthcare is especially important given the worldwide rise in prevalence of chronic diseases and deaths from these diseases. There are many methods for prevention of disease. One of them is prevention of teenage smoking through information giving.
Inhalation of these pathogens affects the respiratory system and can then spread to the rest of the body. Sinus congestion, coughing and sore throats are examples of inflammation of the upper respiratory airway. Air pollution plays a significant role in airborne diseases.
|
Monotremes, marsupials, and placental mammals are subclasses of what?
|
[
"mammals",
"amphibians",
"reptiles",
"birds"
] |
A
|
Monotremes, marsupials, and placental mammals are subclasses of mammals. Almost all living mammals are placental mammals, which are divided into many orders.
The relationships among the three extant divisions of mammals (monotremes, marsupials, and placentals) were long a matter of debate among taxonomists. Most morphological evidence comparing traits such as number and arrangement of teeth and structure of the reproductive and waste elimination systems as well as most genetic and molecular evidence favors a closer evolutionary relationship between the marsupials and placental mammals than either has with the monotremes. The ancestors of marsupials, part of a larger group called metatherians, probably split from those of placental mammals (eutherians) during the mid-Jurassic period, though no fossil evidence of metatherians themselves are known from this time. From DNA and protein analyses, the time of divergence of the two lineages has been estimated to be around 100 to 120 mya.
Marsupials have two lateral vaginas and a medial vagina. The "vagina" of monotremes is better understood as a "urogenital sinus". The uterine systems of placental mammals can vary between a duplex, where there are two uteri and cervices which open into the vagina, a bipartite, where two uterine horns have a single cervix that connects to the vagina, a bicornuate, which consists where two uterine horns that are connected distally but separate medially creating a Y-shape, and a simplex, which has a single uterus.
Marsupial reproductive organs differ from the placental mammals. For them, the reproductive tract is doubled. The females have two uteri and two vaginas, and before birth, a birth canal forms between them, the median vagina.
Similar body shapes are found in the earless seals and the eared seals: they still have four legs, but these are strongly modified for swimming.The marsupial fauna of Australia and the placental mammals of the Old World have several strikingly similar forms, developed in two clades, isolated from each other. The body and especially the skull shape of the thylacine (Tasmanian tiger or Tasmanian wolf) converged with those of Canidae such as the red fox, Vulpes vulpes. Convergence of marsupial and placental mammals
The gray short-tailed opossum possesses several features that make it an ideal research model, particularly in studies of marsupials, as well as the immunological and developmental research on mammalian systems. It breeds relatively easily in laboratory settings, and neonates are exposed and can be readily accessed because, unlike other marsupial species, female opossums lack a pouch: neonates simply cling to the teats. Opossums are born at a stage that is approximately equivalent to 13- to 15-day-old fetal rats or 40-day-old human embryos.
|
What type of mammal gives birth to young that need to develop further in the mother's pouch after birth?
|
[
"humans",
"marsupials",
"whales",
"aborigines"
] |
B
|
Marsupials give birth to a tiny, immature embryo. The embryo then continues to grow and develop in a pouch on the mother’s belly. This is less risky for the mother. However, the embryo is fragile, so it may be less likely to survive than the fetus of a placental mammal.
It is not only mammals that give birth. Some reptiles, amphibians, fish and invertebrates carry their developing young inside them. Some of these are ovoviviparous, with the eggs being hatched inside the mother's body, and others are viviparous, with the embryo developing inside their body, as in the case of mammals.
The requiem sharks maintain a placental link to the developing young, this practice is known as viviparity. This is more analogous to mammalian gestation than to that of other fishes.
This species exhibits the most advanced mode of viviparity of any fish, in which the developed embryos form a highly complex placental connection to the mother at a very small size. Females breed year-round, giving birth to six to 18 pups after a gestation period of 5–6 months. The spadenose shark is harmless to humans and is valued by artisanal and commercial fishers for its meat and fins.
Mating takes place in the trees, with the pair either face to face, or with the male on the female's back. The female gives birth to a single infant after a gestation period of about six months.The young are born already fully furred, and with open eyes. The young animal clings to the mother's underside for the first month of life, by which time it has reached a weight of around 300 grams (10 oz).
The gray short-tailed opossum possesses several features that make it an ideal research model, particularly in studies of marsupials, as well as the immunological and developmental research on mammalian systems. It breeds relatively easily in laboratory settings, and neonates are exposed and can be readily accessed because, unlike other marsupial species, female opossums lack a pouch: neonates simply cling to the teats. Opossums are born at a stage that is approximately equivalent to 13- to 15-day-old fetal rats or 40-day-old human embryos.
|
What is the measure of how closely molecules are packed together?
|
[
"density",
"length",
"volume",
"frequency"
] |
A
|
Density is mass per unit volume. Density is a measure of how closely molecules are packed together. The closer together they are, the greater the density. Since air is a gas, the molecules can pack tightly or spread out.
Assume that the molecules of two different substances are approximately the same size, and regard space as subdivided into a square lattice whose cells are the size of the molecules. (In fact, any lattice would do, including close packing.) This is a crystal-like conceptual model to identify the molecular centers of mass. If the two phases are liquids, there is no spatial uncertainty in each one individually.
Some of the largest molecules are macromolecules or supermolecules. The smallest molecule is the diatomic hydrogen (H2), with a bond length of 0.74 Å.Effective molecular radius is the size a molecule displays in solution. The table of permselectivity for different substances contains examples.
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.
Large molecules can be studied by semi-empirical approximate methods. Even larger molecules are treated by classical mechanics methods that use what are called molecular mechanics (MM). In QM-MM methods, small parts of large complexes are treated quantum mechanically (QM), and the remainder is treated approximately (MM).
The molecular geometry can be determined by various spectroscopic methods and diffraction methods. IR, microwave and Raman spectroscopy can give information about the molecule geometry from the details of the vibrational and rotational absorbance detected by these techniques. X-ray crystallography, neutron diffraction and electron diffraction can give molecular structure for crystalline solids based on the distance between nuclei and concentration of electron density. Gas electron diffraction can be used for small molecules in the gas phase.
|
What is the leading cause of lung cancer?
|
[
"chewing tobacco",
"heredity",
"tuberculosis",
"tobacco smoke"
] |
D
|
Tobacco smoke contains dozens of carcinogens, including nicotine and formaldehyde. Exposure to tobacco smoke is the leading cause of lung cancer.
Worldwide in 2015, the most common causes of cancer death were lung cancer (1.6 million deaths), liver cancer (745,000 deaths), and stomach cancer (723,000 deaths). Lung cancer is largely due to non-infectious causes, such as tobacco smoke. However, liver and stomach cancer are primarily due to infectious causes.
Risk factors for lung disease include tobacco smoking and environmental dust. The underlying mechanism involves unblocked neutrophil elastase and buildup of abnormal A1AT in the liver. It is autosomal co-dominant, meaning that one defective allele tends to result in milder disease than two defective alleles.
In a few cases, only one cause exists: for example, the virus HHV-8 causes all Kaposi's sarcomas. However, with the help of cancer epidemiology techniques and information, it is possible to produce an estimate of a likely cause in many more situations. For example, lung cancer has several causes, including tobacco use and radon gas.
Lung cancer is the most well characterized type of cancer associated with telomerase. There is a lack of substantial telomerase activity in some cell types such as primary human fibroblasts, which become senescent after about 30–50 population doublings. There is also evidence that telomerase activity is increased in tissues, such as germ cell lines, that are self-renewing.
Studies conducted before smoking and lung cancer were scientifically related connected a higher rate of smoking to lung cancer incidence, and eventually mortality 20 years later. In 1775, Percivall Pott’s discovery of the high incidence of scrotal cancer in chimney sweeps demonstrated that charred organic substances were carcinogenic. Wynder used Pott’s research as a foundation for his argument that his hypothesis that smoking leads to the development of lung cancer was biologically valid. In 1912, Isaac Adler connected the rise in primary lung cancer to consumption of cigarettes because of the different smoking habits of men and women.
|
The golgi removes some sugar monomers and substitutes others, producing a large variety of what?
|
[
"electrolytes",
"fats",
"carbohydrates",
"proteins"
] |
C
|
Protein modifications may form a signal sequence that determines the final destination of the protein. For example, the Golgi apparatus adds a mannose-6-phosphate label to proteins destined for lysosomes. Another important function of the Golgi apparatus is in the formation of proteoglycans. Enzymes in the Golgi append proteins to glycosaminoglycans, thus creating proteoglycans. Glycosaminoglycans are long unbranched polysaccharide molecules present in the extracellular matrix of animals.
In the contemporary process, corn is milled to extract corn starch and an "acid-enzyme" process is used, in which the corn-starch solution is acidified to begin breaking up the existing carbohydrates. High-temperature enzymes are added to further metabolize the starch and convert the resulting sugars to fructose. : 808–813 The first enzyme added is alpha-amylase, which breaks the long chains down into shorter sugar chains – oligosaccharides. Glucoamylase is mixed in and converts them to glucose.
Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Some, such as the raffinose series, occur as storage or transport carbohydrates in plants. Others, such as maltodextrins or cellodextrins, result from the microbial breakdown of larger polysaccharides such as starch or cellulose.
They are in substantially equal amounts. To verify the completion of the fermentation they can be quantified by chemical assay (glucose and fructose are "reducing" sugars that react with an alkaline copper solution called Fehling's solution), an enzymatic method, or by infrared spectroscopy. Other sugars are not fermentable at all. After consumption by the yeast, the ratio of non-fermentable sugars (the ones that are not consumed by yeast: arabinose and xylose) is between 0.5 and 1.7 grams per litre. Sugars exercise a control over the taste – they balance the spiciness of the acidity and the burning of the alcohol.
An assay of amylo-1,4 → 1,6 glucan transferases (which removes a block of 6 glucose residues from the 1,4 position and attaches it to the 1,6 position of the same chain)
|
Parenchymal, collenchymal, and sclerenchymal cells are associated with what types of living things?
|
[
"primates",
"parasites",
"fungi",
"plants"
] |
D
|
Different types of plant cells include parenchymal, collenchymal, and sclerenchymal cells. The three types differ in structure and function.
Collenchyma (Greek, ‘Colla’ means gum and ‘enchyma’ means infusion) is a living tissue of primary body like Parenchyma. Cells are thin-walled but possess thickening of cellulose, water and pectin substances (pectocellulose) at the corners where a number of cells join. This tissue gives tensile strength to the plant and the cells are compactly arranged and have very little inter-cellular spaces. It occurs chiefly in hypodermis of stems and leaves.
The main cell types are fibroblasts, macrophages and adipocytes (the subcutaneous tissue contains 50% of body fat). Fat serves as padding and insulation for the body. Microorganisms like Staphylococcus epidermis colonize the skin surface. The density of skin flora depends on region of the skin. The disinfected skin surface gets recolonized from bacteria residing in the deeper areas of the hair follicle, gut and urogenital openings.
Stomochords were initially considered a variant of a primitive notochord, a defining feature of chordates. However, they are now recognized to not share histological composition to that of the notochord found in chordates, lacking the fibrous sheath characteristic of a notochord.In addition, gene expression studies have failed to provide any evidence for homology between the notochord and the stomochord, or between the notochord and any hemichordate structure. The Brachyury (T) gene, which is expressed in the ascidian and other chordates notochord, is not expressed in the stomochord, and collagen is absent. == References ==
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.
Division of meristematic cells provides new cells for expansion and differentiation of tissues and the initiation of new organs, providing the basic structure of the plant body. The cells are small, with small vacuoles or none, and protoplasm filling the cell completely. The plastids (chloroplasts or chromoplasts), are undifferentiated, but are present in rudimentary form (proplastids).
|
What is the name of the location in which a stream or river starts?
|
[
"spring",
"shore",
"source",
"mouth"
] |
C
|
All streams and rivers have several features in common. These features are shown in ( Figure below ). The place where a stream or river starts is its source. The source might be a spring, where water flows out of the ground. Or the source might be water from melting snow on a mountain top. A single stream may have multiple sources. A stream or river probably ends when it flows into a body of water, such as a lake or an ocean. A stream ends at its mouth. As the water flows into the body of water, it slows down and drops the sediment it was carrying. The sediment may build up to form a delta.
A river is a natural watercourse, usually freshwater, flowing toward an ocean, a lake, a sea or another river. A few rivers simply flow into the ground and dry up completely without reaching another body of water. The water in a river is usually in a channel, made up of a stream bed between banks. In larger rivers there is often also a wider floodplain shaped by waters over-topping the channel.
Holy Brook – Stream, probably partly artificial, in the United Kingdom Jordan River – River in West Asia which flows to the Dead Sea Lake Guatavita – Lake in Cundinamarca Department, Colombia Nile – Major river in northeastern Africa Sanctuary of Our Lady of Lourdes – Marian shrine in Hautes-Pyrénées, France Silwan – Palestinian neighborhood in East Jerusalem, site of a sacred spring (Ayn Silwan) Zamzam Well – Well in the Masjid al-Haram in Mecca
Power-law relationships between channel slope, depth, and width are given as a function of discharge by "river regime". In certain languages, distinctions are made among rivers based on their stream order. In French, for example, rivers that run to the sea are called fleuve, while other rivers are called rivière.
An urban stream is a formerly natural waterway that flows through a heavily populated area. Often times, urban streams are low-lying points in the landscape that characterize catchment urbanization. Urban streams are often polluted by urban runoff and combined sewer outflows. Water scarcity makes flow management in the rehabilitation of urban streams problematic.
Deltas and estuaries occur near the mouths of rivers. 2. The lower or downstream end or the most accessible entrance of a valley, canyon, ravine, or cave.
|
What disease occurs when cells in the breast grow out of control and form a tumor?
|
[
"adult breast growth",
"muscle cancer",
"breast cancer",
"muscular cyst"
] |
C
|
Breast cancer is the most common type of cancer in females. It occurs when cells in the breast grow out of control and form a tumor. Breast cancer is rare in teens but becomes more common as females get older. Regular screening is recommended for most women starting around age 40. If found early, breast cancer usually can be cured with surgery.
Cells may grow and pass through the cell cycle normally without arrest or death. However, some tumors cells are MGMT deficient (MGMTd).
The name indicates calcinosis (calcium deposition) which resembles tumor (like a new growth). They are not true neoplasms – they don't have dividing cells. They are just deposition of inorganic calcium with serum exudate. Children and adolescents (6 to 25 years) are the most commonly affected.
Malignancy (from Latin male 'badly', and -gnus 'born') is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A malignant tumor contrasts with a non-cancerous benign tumor in that a malignancy is not self-limited in its growth, is capable of invading into adjacent tissues, and may be capable of spreading to distant tissues. A benign tumor has none of those properties, but may be harmful to health. The term benign in more general medical use characterises a condition or growth that is not cancerous, i.e. does not spread to other parts of the body or invade nearby tissue.
Many cells are invading the surrounding tissue in neoplastic clumps. This corresponds to a poorly differentiated carcinoma.
Cancers are classified by the type of cell that the tumor cells resemble and is therefore presumed to be the origin of the tumor. These types include: Carcinoma: Cancers derived from epithelial cells. This group includes many of the most common cancers and include nearly all those in the breast, prostate, lung, pancreas and colon. Sarcoma: Cancers arising from connective tissue (i.e. bone, cartilage, fat, nerve), each of which develops from cells originating in mesenchymal cells outside the bone marrow.
|
What process refers to the changes that occur in populations of living organisms over time?
|
[
"spontaneous mutation",
"adaptation",
"variation",
"evolution"
] |
D
|
The term evolution describes the changes that occur in populations of living organisms over time. Describing these changes does not address the origin of life. The two are commonly and mistakenly confused. Biological evolution likewise says nothing about cosmology, the Big Bang, or where the universe, galaxy, solar system, or Earth came from.
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.
However, if the change has a positive influence, the mutation may become more and more common in a population until it becomes a fixed genetic piece of that population. Organisms changing via these two options comprise the classic view of natural selection.
evolution The change in the heritable characteristics of populations of biological organisms over successive generations, which may occur by mutation, gene flow, natural selection, or random chance. evolutionary biology The subfield of biology that studies evolution and the evolutionary processes that produced the diversity of life on Earth from a hypothesized single common ancestor. These processes include the descent of species and the origin of new species.
Some conserved core processes, called "exploratory processes", have the ability to generate many different phenotypical outcomes or states. Examples include: the formation of microtubule structures, the development of the nervous system (i.e. connecting of axons and target organs), synapse elimination, muscle patterning, the production of blood vessels, vertebrate immune system, animal learningExploratory processes first generate a very large amount of physiological variation, often at random, and then select or stabilize the most useful ones, with the rest disappearing or dying back. Hence, exploratory processes resemble a Darwinian process operating during development.
A branching process (BP) (see e.g. Jagers (1975)) is a mathematical model to describe the development of a population. Here population is meant in a general sense, including a human population, animal populations, bacteria and others which reproduce in a biological sense, cascade process, or particles which split in a physical sense, and others. Members of a BP-population are called individuals, or particles.
|
Alkenes can react with what to form alcohols?
|
[
"water",
"air",
"proteins",
"sugars"
] |
A
|
Alkenes can react with water to form alcohols.
Similarly, it also reacts quickly with alcohols and carboxylic acids, although less vigorously than with water. With simple Lewis bases (L), Al2Br6 forms adducts, such as AlBr3L.
Hydroazidation of alkenes has been demonstrated
Organomanganese halides react with aldehydes and ketones to the alcohol, with carbon dioxide to the carboxylic acid (tolerating higher operating temperature than corresponding RLi or RMgBr counterparts), sulfur dioxide and isocyanates behaving like soft Grignard reagents. They do not react with esters, nitriles, or amides. They are more sensitive to steric than to electronic effects.
Hydroarylation is again a special case of hydrovinylation. Hydroarylation has been demonstrated for alkyne and alkene substrates. An early example was provided by the Murai reaction, which involves the insertion of alkenes into a C-H bond of acetophenone.
Alkenes are produced by hydrocarbon cracking. Raw materials are mostly natural gas condensate components (principally ethane and propane) in the US and Mideast and naphtha in Europe and Asia. Alkanes are broken apart at high temperatures, often in the presence of a zeolite catalyst, to produce a mixture of primarily aliphatic alkenes and lower molecular weight alkanes. The mixture is feedstock and temperature dependent, and separated by fractional distillation.
|
Wind blown sand contributes to what type of erosion?
|
[
"vegetation",
"sedimentary",
"filtration",
"abrasion"
] |
D
|
Did you ever see workers sandblasting a building to clean it? Sand is blown onto the surface to scour away dirt and debris. Wind-blown sand has the same effect. It scours and polishes rocks and other surfaces. Wind-blown sand may carve rocks into interesting shapes. You can see an example in Figure below . This form of erosion is called abrasion. It occurs any time rough sediments are blown or dragged over surfaces. Can you think of other ways abrasion might occur?.
Sand that is blown by the wind inland to form sand dunes usually develop on shorelines where there is suitably strong winds. This can be a major sink for the sediment budget of a shoreline.
In a desert, for example, the wind deposits siliciclastic material (sand or silt) in some spots, or catastrophic flooding of a wadi may cause sudden deposits of large quantities of detrital material, but in most places eolian erosion dominates. The amount of sedimentary rock that forms is not only dependent on the amount of supplied material, but also on how well the material consolidates. Erosion removes most deposited sediment shortly after deposition.
On sandy beaches, the turbulent backwash of destructive waves removes material forming a gently sloping beach. On pebble and shingle beaches the swash is dissipated more quickly because the large particle size allows greater percolation, thereby reducing the power of the backwash, and the beach remains steep. Compacted fine sediments will form a smooth beach surface that resists wind and water erosion.
Sand and dust storms are natural events that occur in arid regions where the land is not protected by a covering of vegetation. Dust storms usually start in desert margins rather than the deserts themselves where the finer materials have already been blown away. As a steady wind begins to blow, fine particles lying on the exposed ground begin to vibrate.
Other climatic factors such as average temperature and temperature range may also affect erosion, via their effects on vegetation and soil properties. In general, given similar vegetation and ecosystems, areas with more precipitation (especially high-intensity rainfall), more wind, or more storms are expected to have more erosion. In some areas of the world (e.g. the mid-western USA), rainfall intensity is the primary determinant of erosivity, with higher intensity rainfall generally resulting in more soil erosion by water.
|
Bases are ionic compounds consisting of hydroxide ions and a what?
|
[
"cinion",
"carbonate",
"sulfate",
"cation"
] |
D
|
Bases are ionic compounds consisting of hydroxide ions and a cation. Naming and formula writing for bases follows the same guidelines as for other ionic compounds.
When one molecule of base via complete ionization produces three hydroxide ions, the base is said to be triacidic or triprotic. Examples of triacidic bases are: Aluminium hydroxide, ferrous hydroxide, Gold Trihydroxide,
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.
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na+ and hydroxide anions OH−. Sodium hydroxide is a highly corrosive base and alkali that decomposes lipids and proteins at ambient temperatures and may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air.
Aside from NaOH and KOH, which enjoy very large scale applications, the hydroxides of the other alkali metals also are useful. Lithium hydroxide is a strong base, with a pKb of −0.36. Lithium hydroxide is used in breathing gas purification systems for spacecraft, submarines, and rebreathers to remove carbon dioxide from exhaled gas. 2 LiOH + CO2 → Li2CO3 + H2OThe hydroxide of lithium is preferred to that of sodium because of its lower mass. Sodium hydroxide, potassium hydroxide, and the hydroxides of the other alkali metals are also strong bases.
Sample gallery The conjugate base of hydroxamic acids forms is called a hydroxamate. Deprotonation occurs at the NOH group. The resulting conjugate base presents the metal with an anionic, conjugated O,O chelating ligand.
|
What causes the menstrual cycle to be repeated?
|
[
"gravity",
"uteris",
"lack of fertilization",
"ovaries"
] |
C
|
The menstrual cycle is a series of changes in the reproductive system of mature females that repeats every month on average. It includes changes in the uterus as well as development of an egg and ovulation. If fertilization does not occur, menstruation occurs and the cycle repeats.
It may be caused by developmental problems, such as the congenital absence of the uterus, failure of the ovary to receive or maintain egg cells, or delay in pubertal development. Secondary amenorrhoea, ceasing of menstrual cycles after menarche, is defined as the absence of menses for three months in a woman with previously normal menstruation, or six months for women with a history of oligomenorrhoea. It is often caused by hormonal disturbances from the hypothalamus and the pituitary gland, premature menopause, intrauterine scar formation, or eating disorders.
Researchers are divided on whether menstrual synchrony would be adaptive. McClintock has suggested that menstrual synchrony may not be adaptive but rather epiphenomenonal, lacking any biological function. Among those who postulate an adaptive function, one argument is that menstrual synchrony is only a particular aspect of the much more general phenomenon of reproductive synchrony, an occurrence familiar to ecologists studying animal populations in the wild. Whether seasonal, tidal, or lunar, reproductive synchrony is a relatively common mechanism through which co-cycling females can increase the number of males included in the local breeding system.
A woman's menstrual cycle begins, as arbitrarily assigned, with menses. Next is the follicular phase where estrogen levels build as an ovum matures (due to the follicular stimulating hormone, or FSH) within the ovary. When estrogen levels peak, it spurs a surge of luteinizing hormone (LH) which completes maturation and enables the ovum to break through the ovary wall. This is ovulation.
Hypomenorrhea is abnormally light menstrual bleeding. Menorrhagia (meno = prolonged, rrhagia = excessive flow/discharge) is an abnormally heavy and prolonged menstrual period. Metrorrhagia is bleeding at irregular times, especially outside the expected intervals of the menstrual cycle.
Women who have regular periods can take medication just before and during menstruation. Options include progesterone supplements, increasing the dose of their regular anticonvulsant drug, or temporarily adding an anticonvulsant such as clobazam or acetazolamide. If this is ineffective, or when a woman's menstrual cycle is irregular, then treatment is to stop the menstrual cycle occurring. This may be achieved using medroxyprogesterone, triptorelin or goserelin, or by sustained use of oral contraceptives.
|
What happens when turgid cells in a nonwoody tissue push against each other?
|
[
"the tissue dies",
"the tissue melts",
"the tissue stiffens",
"the tissues merge"
] |
C
|
When contracted, the terminal web causes a decrease in diameter of the apex of the cell, causing the microvilli, which are anchored into the terminal web through their stiff actin fibers, to spread apart. This spreading apart of the microvilli aids cells in absorption. == References ==
The motion of the flagella sucks water through passages in the "cobweb" and expels it via the open ends of the bell-shaped chambers.Some types of cells have a single nucleus and membrane each but are connected to other single-nucleus cells and to the main syncytium by "bridges" made of cytoplasm. The sclerocytes that build spicules have multiple nuclei, and in glass sponge larvae they are connected to other tissues by cytoplasm bridges; such connections between sclerocytes have not so far been found in adults, but this may simply reflect the difficulty of investigating such small-scale features. The bridges are controlled by "plugged junctions" that apparently permit some substances to pass while blocking others.
The attraction is attributed to charged groups on the surface of cells and to the presence of fibrinogen and globulins. This aggregated configuration is an arrangement of cells with the least amount of deformation. With very low shear rates, the viscoelastic property of blood is dominated by the aggregation and cell deformability is relatively insignificant.
As the normal site of infection is the gut columnar epithelium, cells are packed closely together and a cell protrusion from one cell will easily push into a neighboring "target" cell without rupturing the target cell membrane or the donor protrusion membrane. At this point, the bacterium at the tip of the protrusion will begin to undergo "fitful movement" caused by continuing polymerization of actin at its rear. After 7–15 minutes, the donor cell membrane pinches off and fitful movement ceases for 15–25 minutes due to depletion of ATP. Subsequently, the target membrane pinches off (taking 30–150 seconds) and the secondary vacuole containing the bacterium forms inside the target cell cytoplasm.
In the gut lumen of the worm, the spores extrude their polar capsules and attach to the gut epithelium by polar filaments. The shell valves then open along the suture line and the binucleate germ cell penetrates between the intestinal epithelial cells of the worm. This cell multiplies, producing many amoeboid cells by an asexual cell fission process called merogony.
|
What is the waxy substance that epidermal cells secrete?
|
[
"cellulose",
"cuticle",
"bile",
"saliva"
] |
B
|
Dermal tissue covers the outside of a plant in a single layer of cells called the epidermis. You can think of the epidermis as the plant’s skin. It mediates most of the interactions between a plant and its environment. Epidermal cells secrete a waxy substance called cuticle , which coats, waterproofs, and protects the above-ground parts of plants. Cuticle helps prevent water loss, abrasions, infections, and damage from toxins.
In zoology, the epidermis is an epithelium (sheet of cells) that covers the body of a eumetazoan (animal more complex than a sponge). Eumetazoa have a cavity lined with a similar epithelium, the gastrodermis, which forms a boundary with the epidermis at the mouth.Sponges have no epithelium, and therefore no epidermis or gastrodermis. The epidermis of a more complex invertebrate is just one layer deep, and may be protected by a non-cellular cuticle. The epidermis of a higher vertebrate has many layers, and the outer layers are reinforced with keratin and then die. == References ==
It is maintained as a stem cell layer through an autocrine signal, TGF alpha, and through paracrine signaling from FGF7 (keratinocyte growth factor) produced by the dermis below the basal cells. In mice, over-expression of these factors leads to an overproduction of granular cells and thick skin.Hair and feathers are formed in a regular pattern and it is believed to be the result of a reaction-diffusion system. This reaction-diffusion system combines an activator, Sonic hedgehog, with an inhibitor, BMP4 or BMP2, to form clusters of cells in a regular pattern.
Topical cantharidin is absorbed by the lipid membranes of epidermal cells, causing the release of serine proteases, enzymes that break the peptide bonds in proteins. This causes the disintegration of desmosomal plaques, cellular structures involved in cell-to-cell adhesion, leading to detachment of the tonofilaments that hold cells together. The process leads to the loss of cellular connections (acantholysis), and ultimately results in blistering of the skin. Lesions heal without scarring.
Within the epidermis keratinocytes are associated with other cell types such as melanocytes and Langerhans cells. Keratinocytes form tight junctions with the nerves of the skin and hold the Langerhans cells and intra-dermal lymphocytes in position within the epidermis. Keratinocytes also modulate the immune system: apart from the above-mentioned antimicrobial peptides and chemokines they are also potent producers of anti-inflammatory mediators such as IL-10 and TGF-β.
The main cell types are fibroblasts, macrophages and adipocytes (the subcutaneous tissue contains 50% of body fat). Fat serves as padding and insulation for the body. Microorganisms like Staphylococcus epidermis colonize the skin surface. The density of skin flora depends on region of the skin. The disinfected skin surface gets recolonized from bacteria residing in the deeper areas of the hair follicle, gut and urogenital openings.
|
What is the length of the route between two points?
|
[
"distance",
"speed",
"direction",
"velocity"
] |
A
|
Distance is the length of the route between two points. The distance of a race, for example, is the length of the track between the starting and finishing lines. In a 100-meter sprint, that distance is 100 meters.
The distance travelled by an object is the length of a specific path travelled between two points, such as the distance walked while navigating a maze. This can even be a closed distance along a closed curve which starts and ends at the same point, such as a ball thrown straight up, or the Earth when it completes one orbit. This is formalized mathematically as the arc length of the curve.
The length of the top line to the tow point is the length between the two bridle to spine connection points. The length of the bottom bridle to the tow point is between 1⁄2 and 2 inches (13 and 51 mm) longer than the length of the two spine connections. The spine of the kite has a slight convex curve toward the face of the kite.
Pathfinding or pathing is the plotting, by a computer application, of the shortest route between two points. It is a more practical variant on solving mazes. This field of research is based heavily on Dijkstra's algorithm for finding the shortest path on a weighted graph. Pathfinding is closely related to the shortest path problem, within graph theory, which examines how to identify the path that best meets some criteria (shortest, cheapest, fastest, etc) between two points in a large network.
The train is moving at 40 km/h. The figure depicts the man and train at two different times: first, when the journey began, and also one hour later at 2:00 pm. The figure suggests that the man is 50 km from the starting point after having traveled (by walking and by train) for one hour.
An altitude of 9 statute miles (14.5 km) and a range of 11.5 statute miles (18.5 km) were obtained, and a speed of 2,021.6 miles per hour (3,254 km/h) was reached. Flight time 8 minutes 11 seconds. Payload 1,007 kg.
|
According to the first law of thermodynamics, what can neither be created nor destroyed?
|
[
"fuel",
"food",
"energy",
"light"
] |
C
|
Chapter 46 1 Figure 46.8 According to the first law of thermodynamics, energy can neither be created nor destroyed. Eventually, all energy consumed by living systems is lost as heat or used for respiration, and the total energy output of the system must equal the energy that went into it. 3 Figure 46.17 C: Nitrification by bacteria converts nitrates (NO3−) to nitrites (NO2−). 4 D 6 B 8 A 10 D 12 D 14 B 16 A 18 A 20 C 21 Food webs show interacting groups of different species and their many interconnections with each other and the environment. Food chains are linear aspects of food webs that describe the succession of organisms consuming one another at defined trophic levels. Food webs are a more accurate representation of the structure and dynamics of an ecosystem. Food chains are easier to model and use for experimental studies. 23 Grazing food webs have a primary producer at their base, which is either a plant for terrestrial ecosystems or a phytoplankton for aquatic ecosystems. The producers pass their energy to the various trophic levels of consumers. At the base of detrital food webs are the decomposers, which pass this energy to a variety of other consumers. Detrital food webs are important for the health of many grazing food webs because they eliminate dead and decaying organic material, thus, clearing space for new organisms and removing potential causes of disease. By breaking down dead organic matter, decomposers also make mineral nutrients available to primary producers; this process is a vital link in nutrient cycling. 25 NPE measures the rate at which one trophic level can use and make biomass from what it attained in the previous level, taking into account respiration, defecation, and heat loss. Endotherms have high metabolism and generate a lot of body heat. Although this gives them advantages in their activity level in colder temperatures, these organisms are 10 times less efficient at harnessing the energy from the food they eat compared with cold-blooded animals, and thus have to eat more and more often. 27 Many factors can kill life in a lake or ocean, such as eutrophication by nutrient-rich surface runoff, oil spills, toxic waste spills, changes in climate, and the dumping of garbage into the ocean. Eutrophication is a result of nutrient-rich runoff from land using artificial fertilizers high in nitrogen and phosphorus. These nutrients cause the rapid and excessive growth of microorganisms, which deplete local dissolved oxygen and kill many fish and other aquatic organisms.
A common corollary of the statement is that heat does not spontaneously pass from a colder body to a warmer body. The third law of thermodynamics states that a system's entropy approaches a constant value as the temperature approaches absolute zero. With the exception of non-crystalline solids (glasses), the entropy of a system at absolute zero is typically close to zero.The first and second laws prohibit two kinds of perpetual motion machines, respectively: the perpetual motion machine of the first kind which produces work with no energy input, and the perpetual motion machine of the second kind which spontaneously converts thermal energy into mechanical work.
Then, according to the second law of thermodynamics, the whole undergoes changes and eventually reaches a new and final equilibrium with the surroundings. Following Planck, this consequent train of events is called a natural thermodynamic process. It is allowed in equilibrium thermodynamics just because the initial and final states are of thermodynamic equilibrium, even though during the process there is transient departure from thermodynamic equilibrium, when neither the system nor its surroundings are in well defined states of internal equilibrium.
The first law of thermodynamics for closed systems was originally induced from empirically observed evidence, including calorimetric evidence. It is nowadays, however, taken to provide the definition of heat via the law of conservation of energy and the definition of work in terms of changes in the external parameters of a system. The original discovery of the law was gradual over a period of perhaps half a century or more, and some early studies were in terms of cyclic processes.The following is an account in terms of changes of state of a closed system through compound processes that are not necessarily cyclic. This account first considers processes for which the first law is easily verified because of their simplicity, namely adiabatic processes (in which there is no transfer as heat) and adynamic processes (in which there is no transfer as work).
"The Physics and Mathematics of the Second Law of Thermodynamics". Phys. Rep.
Due to that, the effort associated with organizing the world adequately to our own needs continues through the whole life. It cannot be ceased because of the second law of thermodynamics. In order to decrease its own entropy and the entropy of its immediate surroundings, the organism must expend energy.
|
What are the three primary pigment colors?
|
[
"red, white, blue",
"green, orange, purple",
"red, green, blue",
"cyan, yellow, magenta"
] |
D
|
Pigments are substances that color materials by reflecting light of certain wavelengths and absorbing light of other wavelengths. The primary pigment colors are cyan, yellow, and magenta. They can be combined to produce all other colors.
The primary colors in an RGB color wheel are red, green, and blue, because these are the three additive colors—the primary colors of light. The secondary colors in an RGB color wheel are cyan, magenta, and yellow because these are the three subtractive colors—the primary colors of pigment. The tertiary color names used in the descriptions of RGB (or equivalently CMYK) systems are shown below.
Rather than adopting an updated set of primary colors, proponents of split-primary theory explain this lack of chroma by the purported presence of chemical impurities, small amounts of other colors, in the paints, or biases away from the ideal primary toward one or the other of the adjacent colors. Every red paint, for example, is said to be tainted with, or biased toward, either blue or yellow, every blue paint toward either red or green, and every yellow toward either green or orange. These biases are said to result in mixtures that contain sets of complementary colors, darkening the resulting color.
Each different pigment is especially sensitive to a certain wavelength of light (that is, the pigment is most likely to produce a cellular response when it is hit by a photon with the specific wavelength to which that pigment is most sensitive). The three types of cones are L, M, and S, which have pigments that respond best to light of long (especially 560 nm), medium (530 nm), and short (420 nm) wavelengths respectively.Since the likelihood of response of a given cone varies not only with the wavelength of the light that hits it but also with its intensity, the brain would not be able to discriminate different colors if it had input from only one type of cone. Thus, interaction between at least two types of cone is necessary to produce the ability to perceive color.
Light areas are typically yellow, red, orange or brown, and the spots vary in size and shape and numbers. Some species have striped or checkered patterns. The pigment carotene creates the lighter colours, and melanins create darker colours.
The following are some of the attributes of pigments that determine their suitability for particular manufacturing processes and applications: Lightfastness and sensitivity for damage from ultraviolet light Heat stability Toxicity Tinting strength Staining Dispersion (which can be measured with a Hegman gauge) Opacity or transparency Resistance to alkalis and acids Reactions and interactions between pigments
|
How do organophostbate pesticides work?
|
[
"inhibiting reticulum",
"inhibiting cryptosporidium",
"inhibiting testosterone",
"inhibiting acetylcholinesterase"
] |
D
|
Historically, people could do little to protect their crops from locusts, although eating the insects may have been some compensation. By the early 20th century, efforts were made to disrupt the development of the insects by cultivating the soil where eggs were laid, collecting hoppers with catching machines, killing them with flamethrowers, trapping them in ditches, and crushing them with rollers and other mechanical methods. By the 1950s, the organochloride dieldrin was found to be an extremely effective insecticide, but it was later banned in most countries because of its persistence in the environment and its accumulation in the food chain. In years when locust control is needed, the hoppers are targeted early by applying water-based contact pesticides from tractor-based sprayers.
When the pesticide degrades, it is broken down into several chemicals. Organophosphates degrade faster than the organochlorides. The greater acute toxicity of OPPs results in the elevated risk associated with this class of compounds (see the Toxicity section below).
Octamethylenediamine is used as a versatile intermediate in manufacturing pesticides, especially fungicides.
Glyphosate is another chemical method of control. These two herbicides are usually sprayed directly on the plants in late fall to prevent other plants from being targeted. These steps must be repeated annually, or whenever regrowth is observed.
The pyrethrins are a class of organic compounds normally derived from Chrysanthemum cinerariifolium that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and is often considered an organic insecticide when it is not combined with piperonyl butoxide or other synthetic adjuvants. Their insecticidal and insect-repellent properties have been known and used for thousands of years. Pyrethrins are gradually replacing organophosphates and organochlorides as the pesticides of choice as the latter compounds have been shown to have significant and persistent toxic effects to humans.They first appeared on markets in the 1900's and have been continually used since then in products such as bug bombs, building insect sprays, and even to spray animals so that they do not get infectious diseases.
|
In the case of a light bulb, electricity is converted to light and what kind of energy?
|
[
"thermal",
"nuclear",
"abstract",
"chemical"
] |
A
|
Most circuits have devices such as light bulbs that convert electric energy to other forms of energy. In the case of a light bulb, electricity is converted to light and thermal energy.
By the 1870s, Davy's arc lamp had been successfully commercialized, and was used to light many public spaces. Efforts by Joseph Swan and Thomas Edison led to commercial incandescent light bulbs becoming widely available in the 1880s, and by the early twentieth century these had completely replaced arc lamps.The energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern electric lighting is powered by centrally generated electric power, but lighting may also be powered by mobile or standby electric generators or battery systems. Battery-powered light is often reserved for when and where stationary lights fail, often in the form of flashlights or electric lanterns, as well as in vehicles.
For a given quantity of light, an incandescent light bulb consumes more power and emits more heat than a fluorescent lamp. In buildings where air conditioning is used, incandescent lamps' heat output increases load on the air conditioning system. While heat from lights will reduce the need to run a building's heating system, the latter can usually produce the same amount of heat at lower cost than incandescent lights.
Lamps used for lighting are commonly labelled with their light output in lumens and, in many jurisdictions, that is required by law. A 23 W spiral compact fluorescent lamp emits about 1,400–1,600 lm. Many compact fluorescent lamps and other alternative light sources are labelled as being equivalent to an incandescent bulb with a specific power.
Incandescent light bulbs use a tungsten filament heated to high temperature to produce visible light and, necessarily, even more infrared radiation. Round bulbs, often tinted red to reduce visible light, provide infrared radiant heat suitable for warming of people or animals, but the power density available is low. The development of quartz halogen linear lamps allowed much higher power density up to 200 watts/inch of lamp (8 w/mm), useful for industrial heating, drying and processing applications. By adjusting the voltage applied to incandescent lamps, the spectrum of the radiated energy can be made to reduce visible light and emphasize infrared energy production.
Permanent light fixtures, such as dining room chandeliers, may have no switch on the fixture itself, but rely on a wall switch. Fixtures require an electrical connection to a power source, typically AC mains power, but some run on battery power for camping or emergency lights.
|
Where in relation to the home, are levels of vocs found to be higher?
|
[
"indoors",
"On slopes",
"in Fields",
"outdoors"
] |
A
|
The processes of evolution are fundamental to much of biology. Why do people have such a hard time understanding them?.
Health Canada classifies VOCs as organic compounds that have boiling points roughly in the range of 50 to 250 °C (122 to 482 °F). The emphasis is placed on commonly encountered VOCs that would have an effect on air quality.
The EPA regulates VOCs mainly because of their ability to create photochemical smog and regards reducing the concentration of VOC as an important to health and environmental goal.
Volatile organic compounds (VOCs) are gases emitted by various solids or liquids, many of which have short- and long-term adverse health effects. Solvents in traditional paints often contain high quantities of VOCs. Low VOC paints improve indoor air quality and reduce urban smog. The beneficial characteristics of such paints include low odor, clean air, and safer technology, as well as excellent durability and a washable finish.
The dens often consist of no more than a simple, blind-ending tunnel, but are sometimes more complex, including one or more nesting chambers lined with grass. Each individual uses a number of dens, usually no more than five, which it alternates between on different days.Eastern quolls are solitary, and tend to avoid one another, but can form loose 'neighbourhoods'. Home ranges are typically around 35 ha (86 acres) for females, and 44 ha (110 acres) for males, with the latter increasing dramatically during the breeding season.
There are many systems of house division. In most, the ecliptic is divided into houses and the ascendant (eastern horizon) marks the cusp, or beginning, of the first house, and the descendant (western horizon) marks the cusp of the seventh house. Many systems, called quadrant house systems, also use the midheaven (medium coeli) as the cusp of the tenth house. Goals for a house system include ease of computation; agreement with the "quadrant" concept (ascendant on the first house cusp and midheaven on the tenth); defined and meaningful behaviour in the polar regions; acceptable handling of heavenly bodies of high latitude (a distinct problem from high-latitude locations on the Earth's surface); and symbolic value.
|
Density and pressure of air decreases with what?
|
[
"altitude",
"temperature",
"humidity",
"horizontal distance"
] |
A
|
Like density, the pressure of the air decreases with altitude. There is less air pressing down from above the higher up you go. Look at the bottle in Figure below . It was drained by a hiker at the top of a mountain. Then the hiker screwed the cap on the bottle and carried it down to sea level. At the lower altitude, air pressure crushed it. Can you explain why?.
This led Aristotle to speculate that the rate of falling is proportional to the weight and inversely proportional to the density of the medium. From his experience with objects falling in water, he concluded that water is approximately ten times denser than air. By weighing a volume of compressed air, Galileo showed that this overestimates the density of air by a factor of forty.
The amount of air that is lost though this mechanism is dependent on vehicle speed, surface roughness and the total area of the lift pads. The vehicle air pumps must supply new pressurized air to make up for these losses. As the vehicle weight and lift pad area is fixed, for a given vehicle design the volume of air that needs to be ingested by the pumps increases with speed.
The air moves down the pressure gradient through the airways of the lungs and into the alveoli until the pressure of the air and that in the alveoli are equal, that is, the movement of air by bulk flow stops once there is no longer a pressure gradient. Second, there is a "diffusion" process. The air arriving in the alveoli has a higher concentration of oxygen than the "stale" air in the alveoli.
The volume increase causes air pressure within the thorax to decrease, allowing us to inhale. Additionally, as air pressure within the thorax drops, blood pressure in the thoracic veins also decreases, falling below the pressure in the abdominal veins. This causes blood to flow along its pressure gradient from veins outside the thorax, where pressure is higher, into the thoracic region, where pressure is now lower.
One can calculate the atmospheric pressure at a given altitude. Temperature and humidity also affect the atmospheric pressure. Pressure is proportional to temperature and inversely proportional to humidity.
|
Energy is absorbed in the process of converting a liquid at its boiling point into a what?
|
[
"mesh",
"plasma",
"gas",
"solid"
] |
C
|
Energy is absorbed in the process of converting a liquid at its boiling point into a gas. As with the melting of a solid, the temperature of a boiling liquid remains constant and the input of energy goes into changing the state. The molar heat of vaporization of a substance is the heat absorbed by one mole of that substance as it is converted from a liquid to a gas. As a gas condenses to a liquid, heat is released. The molar heat of condensation of a substance is the heat released by one mole of that substance as it is converted from a gas to a liquid. Since vaporization and condensation of a given substance are the exact opposite processes, the numerical value of the molar heat of vaporization is the same as the numerical value of the molar heat of condensation, but opposite in sign. In other words, .
Fluid, usually water, in the absorber tubes collect the trapped heat and transfer it to a heat storage vault. Heat is transferred either by conduction or convection. When water is heated, kinetic energy is transferred by conduction to water molecules throughout the medium.
When a substance undergoes a phase transition (changes from one state of matter to another) it usually either takes up or releases energy. For example, when water evaporates, the increase in kinetic energy as the evaporating molecules escape the attractive forces of the liquid is reflected in a decrease in temperature. The energy required to induce the phase transition is taken from the internal thermal energy of the water, which cools the liquid to a lower temperature; hence evaporation is useful for cooling. See Enthalpy of vaporization. The reverse process, condensation, releases heat. The heat energy, or enthalpy, associated with a solid to liquid transition is the enthalpy of fusion and that associated with a solid to gas transition is the enthalpy of sublimation.
Heat is removed in a two-phase system, where the liquid boils when it comes in contact with hot components due to its low boiling point. The system takes advantage of a concept known as “latent heat” which is the heat (thermal energy) required to change the phase of a fluid, this occurs when the two-phase coolant comes in contact with the heated electronics in the bath that are above the coolants boiling point. Once the two-phase coolant enters its gas phase it must be cooled or condensed, typically through the use of water cooled coils placed in the top of the tank.
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.
== Thermal conductivity of liquid ==
|
Images in what type of mirror are reversed left and right but not reversed top and bottom?
|
[
"concave",
"plane mirror",
"virtual",
"convex"
] |
B
|
Images in a plane mirror are reversed left and right but not reversed top and bottom.
Usually, a single control is used to control both left and right side mirrors. A mirror is selected by a switch or a knob. The mirror selector usually has a neutral position with no mirrors selected, to prevent accidental changes of the view.
This was done to save space, as a large CRT monitor would otherwise poke out the back of the cabinet. To correct for the mirrored image, some games had an option to flip the video output using a dip switch setting.
This use of the mirror often results in right-handed painters representing themselves as left-handed (and vice versa). Usually the face painted is therefore a mirror image of what the rest of the world saw, unless two mirrors were used. Most of Rembrandt's self-portraits before 1660 show only one hand – the painting hand is left unpainted.
On a few asymmetrical aircraft the left and right hand sides are not mirror-images of each other: Asymmetric layout: the Blohm & Voss BV 141 had separate fuselage and crew nacelle offset on either side to give the crew a good field of view. Asymmetric span: on several Italian fighters such as the Ansaldo SVA, one wing was slightly longer than the other to help counteract engine torque. Oblique wing: one wing sweeps forward and the other back. The NASA AD-1 had a full-span wing structure with variable sweep.
Isometries requiring an odd number of mirrors — reflection and glide reflection — always reverse left and right. The even isometries — identity, rotation, and translation — never do; they correspond to rigid motions, and form a normal subgroup of the full Euclidean group of isometries. Neither the full group nor the even subgroup are abelian; for example, reversing the order of composition of two parallel mirrors reverses the direction of the translation they produce. Since the even subgroup is normal, it is the kernel of a homomorphism to a quotient group, where the quotient is isomorphic to a group consisting of a reflection and the identity. However the full group is not a direct product, but only a semidirect product, of the even subgroup and the quotient group.
|
What do cells produce as they age?
|
[
"carcinogens",
"wrinkles",
"oxidants",
"proto-oncogenes"
] |
D
|
Thus an old cell can give rise to a newborn, which has a typical lifespan: the age of the donor cell is “wiped clean” and returned to a youthful state. Notably, in classical animal cloning the rejuvenation process involves a return to an embryonic form. Thus the specialized functions of the adult cell are also “wiped clean” and returned to an embryonic cell type.
They reproduce in two manners, firstly in a way that their progeny will differentiate, and thus contribute functionally to the tissue, secondly remaining uncommitted and replenishing the stem cell pool. They play a dual role of generating the various cells that comprise mature tissue by differentiation, while also self-replicating just to sustain the stem cell population. They achieve this divergence through asymmetric cell division.
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.
Consistent with this, telomerase-immortalised cells continued to age (according to the epigenetic clock) without having been treated with any senescence inducers or DNA-damaging agents, re-affirming the independence of the process of epigenetic ageing from telomeres, cellular senescence, and the DNA damage response pathway. Although the uncoupling of senescence from cellular aging appears at first sight to be inconsistent with the fact that senescent cells contribute to the physical manifestation of organism ageing, as demonstrated by Baker et al., where removal of senescent cells slowed down aging.The epigenetic clock analysis of senescence, however, suggests that cellular senescence is a state that cells are forced into as a result of external pressures such as DNA damage, ectopic oncogene expression and exhaustive proliferation of cells to replenish those eliminated by external/environmental factors. These senescent cells, in sufficient numbers, will probably cause the deterioration of tissues, which is interpreted as organism ageing.
Different tissues and the cells they consist of need to orchestrate their work in a tightly controlled manner so that the organism as a whole can function. One of the main ways this is achieved is through excreting signal molecules into the blood where they make their way to other tissues, affecting their behavior. The profile of these molecules changes as we age. One of the most prominent changes in cell signaling biomarkers is "inflammaging", the development of a chronic low-grade inflammation throughout the body with advanced age.
|
The body of the simplest sponges takes the shape of a cylinder with a large central cavity, called?
|
[
"spongocoel",
"spicule",
"vacuole",
"spirogyra"
] |
A
|
The body of the simplest sponges takes the shape of a cylinder with a large central cavity, the spongocoel. Water enters the spongocoel from numerous pores in the body wall. Water flows out through a large opening called the osculum (Figure 15.9). However, sponges exhibit a diversity of body forms, which vary in the size and branching of the spongocoel, the number of osculi, and where the cells that filter food from the water are located. Sponges consist of an outer layer of flattened cells and an inner layer of cells called choanocytes separated by a jellylike substance called mesohyl. The mesohyl contains embedded amoeboid cells that secrete tiny needles called spicules or protein fibers that help give the sponge its structural strength. The cell body of the choanocyte is embedded in mesohyl but protruding into the spongocoel is a mesh-like collar surrounding a single flagellum. The beating of flagella from all choanocytes moves water through the sponge. Food particles are trapped in mucus produced by the sieve-like collar of the choanocytes and are ingested by phagocytosis. This process is called intracellular digestion. Amoebocytes take up nutrients repackaged in food vacuoles of the choanocytes and deliver them to other cells within the sponge.
There is a fir-tree like concentration of spicules running through the body wall with the branches either having rounded or knobbly ends. The form of the sponge varies according to the location in which it is found. It often has a mitten-like structure or may be tall and cylindrical or bowl-like but in areas with strong currents can be dense and compact.
The medium sponges are also unattached; however, they still have great stability with their shape and sediment concentration. Lastly, the larger sponges are attached on their bottom-end. Typically, 67% of their body is buried in sand.
Silica is first laid out as small 2 μm granules that are fused to bigger spheres (or fused together within process of biosintering in Hexactinellida. After some time, amorphous silica is added, forming evenly-deposited concentric layers, separated from each other by ultrathin organic interlayers. At this stage, immature spicules are secreted from the sclerocyte and covered by pseudopodia of one to several cells, and the process of silica deposition and spicule growth continues.After completing the deposition of silica (or during this phase), the spicule is transported to the right place in the sponge body by crawling mesohyl cells, where spongocytes secrete spongin fibrils around them and connect them with adjacent spicules.
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.
Sponges have three asexual methods of reproduction: after fragmentation, by budding, and by producing gemmules. Fragments of sponges may be detached by currents or waves. They use the mobility of their pinacocytes and choanocytes and reshaping of the mesohyl to re-attach themselves to a suitable surface and then rebuild themselves as small but functional sponges over the course of several days. The same capabilities enable sponges that have been squeezed through a fine cloth to regenerate.
|
Laid on dry land by reptiles, amniotic eggs have what that prevents them from drying out?
|
[
"double shells",
"double yolks",
"waterproof membranes",
"oil coating"
] |
C
|
Loggerhead turtles spend most of their life in the ocean. Adult female loggerheads go ashore briefly to lay their eggs in the sand. Then they return to the water and leave the eggs to hatch on their own. Figure below shows baby loggerheads on a beach shortly after hatching. The baby turtles must make their way back to the water, hopefully without being snatched up by a predator. Loggerhead turtles are reptiles. Unlike amphibians, turtles and other reptiles can lay their eggs on dry land. That’s because they produce amniotic eggs. Amniotic eggs have waterproof membranes to prevent them from drying out.
If the egg layers are too thick they suffer from oxygen depletion and often die, entangled in a maze of mucus. They need substantial water microturbulence, generally provided by wave action or coastal currents.
The majority of insects hatch from eggs. The fertilization and development takes place inside the egg, enclosed by a shell (chorion) that consists of maternal tissue. In contrast to eggs of other arthropods, most insect eggs are drought resistant. This is because inside the chorion two additional membranes develop from embryonic tissue, the amnion and the serosa.
After internal fertilization and the habit of laying eggs in terrestrial environments became a reproduction strategy amongst the amniote ancestors, the next major breakthrough appears to have involved a gradual replacement of the gelatinous coating covering the amphibian egg with a fibrous shell membrane. This allowed the egg to increase both its size and in the rate of gas exchange, permitting a larger, metabolically more active embryo to reach full development before hatching. Further developments, like extraembryonic membranes (amnion, chorion, and allantois) and a calcified shell, were not essential and probably evolved later.
There is some evidence that non-avian dinosaurs also practiced brooding. A specimen of the extinct Mongolian oviraptorid Citipati osmolskae was discovered in a chicken-like brooding position in 1993, which may indicate that they had begun using an insulating layer of feathers to keep the eggs warm.Several deinonychosaur and oviraptorosaur specimens have also been found preserved on top of their nests, likely brooding in a bird-like manner.Lungless salamanders in the family Plethodontidae lay a small number of eggs in a cluster among damp leaf litter. The female salamander often broods the eggs and in the genus Ensatinas, she has been observed to coil around them and press her throat area against them, effectively massaging them with a mucous secretion. The black mountain salamander mother broods her eggs, guarding them from predation as the larvae feed on the yolks of their eggs.
The ability of the embryo to tolerate extreme water loss is due to the parental behaviour in species colonising in different environments. Studies show that wild habitats of C. livia and other birds have a higher rate tolerance of various humidity levels, but C. livia prefers areas where the humidity closely matches its native breeding conditions. : 9 The pore areas of the shells allow water to diffuse in and out of the shell, preventing the possible harming of the embryo due to the high rates of water retention.
|
What three rs represent the steps that you personally can take to conserve our natural resources and minimize waste?
|
[
"rinse, reuse, recycle",
"remove, reduce, reuse",
"reduce, reuse, recycle",
"reduce, reuse, re-educate"
] |
C
|
Reduce, reuse, and recycle. There are steps that you personally can take to conserve our natural resources and reduce waste. The waste that an individual creates is small in proportion to all the waste produced by society. Yet all small contributions, when added up, make a difference.
Conserving energy Conserving resources Reducing pollution Reducing waste
The EMS helps to develop, implement, manage, coordinate and monitor environmental policies. Waste reduction begins at the design phase through pollution prevention and waste minimization. Waste can be limited by ‘reduce, reuse & recycle’ Reduce resource usage Reduce pollution
During emergencies such as natural disasters and armed conflicts more waste may be produced, while waste management is given low priority compared with other services. Existing waste management services and infrastructures can be disrupted, leaving communities with unmanaged waste and increased littering. Under these circumstances human health and the environment are often negatively impacted.Natural disasters (e.g. earthquakes, tsunamis, hurricanes) have the potential to generate a significant amount of waste within a short period. Waste management systems can be out of action or curtailed, often requiring considerable time and funding to restore.
Heavy pruning: To add biomass to the soil, retain soil moisture, open up canopy, increase carbon capture and transpiration. 'Water is planted (‘Água se planta!’)' By introducing plants that store water, and increase transpiration. 'Turn our enemies into our friends.' Farmers should look for plants that are green all year (even in severe drought, especially weeds) and plant many of these. These should include tree such as eucalypts that if managed correctly can help protect and foster less robust species, and produce much organic matter quickly to cover and rebuild the soil.
These are use of electricity by the community; use of fuel in residential and commercial stationary combustion equipment; on‐road passenger and freight motor vehicle travel; use of energy in drinking water and wastewater treatment and distribution; and generation of solid waste by the community. Reporting guidance covers a variety of approaches, and organizations can include one or more of them. These include GHG activities and sources over which a local government has significant influence; GHG activities of community interest; household consumption inventories; and an inventory that incorporates the GHG emissions (and removals) from land use.
|
What is the process that allows organisms with better traits to survive and produce?
|
[
"spontaneous mutation",
"adaptation",
"natural selection",
"succession"
] |
C
|
Evolution occurs by natural selection, the process by which organisms with traits that better enable them to adapt to their environment will tend to survive and reproduce in greater numbers. Evolution is due to differences in the survival and reproduction of individuals within a population.
In addition, a females ultimate reproductive success is limited due to ability to distribute her time and energy towards reproducing. Peter T. Ellison states, "The metabolic task of converting energy from the environment into viable offspring falls to the female, and the rate at which she can produce offspring is limited by the rate at which she can direct metabolic energy to the task" The reasoning for the transfer of energy from one category to another takes away from each individual category overall. For example, if a female has not reached menarche yet, she will only need to be focusing her energy into growth and maintenance because she cannot yet place energy towards reproducing.
Natural Selection is the process by which organisms that are better adapted to their environment are selected to survive and reproduce more offspring. Natural selection selects for the phenotype or the characteristics of an organism that gives the organism a reproductive advantage in which it becomes the gene pool of a population. In addition, mutations also arise in the genome of an individual organism and offspring(s) can inherit such mutations. This genetic variation allows more organisms to adapt to a changing environment.
One highly sought after trait is insect resistance. This trait increases a crop's resistance to pests and allows for a higher yield. An example of this trait are crops that are genetically engineered to make insecticidal proteins originally discovered in (Bacillus thuringiensis).
Some conserved core processes, called "exploratory processes", have the ability to generate many different phenotypical outcomes or states. Examples include: the formation of microtubule structures, the development of the nervous system (i.e. connecting of axons and target organs), synapse elimination, muscle patterning, the production of blood vessels, vertebrate immune system, animal learningExploratory processes first generate a very large amount of physiological variation, often at random, and then select or stabilize the most useful ones, with the rest disappearing or dying back. Hence, exploratory processes resemble a Darwinian process operating during development.
Involving evolutionary physiology and environmental physiology, comparative physiology considers the diversity of functional characteristics across organisms.
|
What is the term for a substance that increases the rate of a chemical reaction but is not changed or used up in the reaction?
|
[
"a catalyst",
"a mechanism",
"an acid",
"a contribute"
] |
A
|
Some reactions need extra help to occur quickly. They need another substance, called a catalyst. A catalyst is a substance that increases the rate of a chemical reaction but is not changed or used up in the reaction. The catalyst can go on to catalyze many more reactions.
For example, sulfur disrupts the production of methanol by poisoning the Cu/ZnO catalyst. Substances that increase reaction rate are called promoters. For example, the presence of alkali metals in ammonia synthesis increases the rate of N2 dissociation.The presence of poisons and promoters can alter the activation energy of the rate-limiting step and affect a catalyst's selectivity for the formation of certain products.
In chemistry, reactivity is the impulse for which a chemical substance undergoes a chemical reaction, either by itself or with other materials, with an overall release of energy. Reactivity refers to: the chemical reactions of a single substance, the chemical reactions of two or more substances that interact with each other, the systematic study of sets of reactions of these two kinds, methodology that applies to the study of reactivity of chemicals of all kinds, experimental methods that are used to observe these processes theories to predict and to account for these processes.The chemical reactivity of a single substance (reactant) covers its behavior in which it: Decomposes Forms new substances by addition of atoms from another reactant or reactants Interacts with two or more other reactants to form two or more productsThe chemical reactivity of a substance can refer to the variety of circumstances (conditions that include temperature, pressure, presence of catalysts) in which it reacts, in combination with the: Variety of substances with which it reacts Equilibrium point of the reaction (i.e., the extent to which all of it reacts) Rate of the reactionThe term reactivity is related to the concepts of chemical stability and chemical compatibility.
The rate of any given reaction, Reactants ⟶ Products {\displaystyle {\ce {Reactants -> Products}}} is governed by the rate law: Rate = k ⋅ {\displaystyle {\text{Rate}}=k\cdot } where the rate is the change in the molar concentration in one second in the rate-determining step of the reaction (the slowest step), is the product of the molar concentration of all the reactants raised to the correct order, known as the reaction order, and k is the reaction constant, which is constant for one given set of circumstances (generally temperature and pressure) and independent of concentration. The greater the reactivity of a compound the higher the value of k and the higher the rate. For instance, if, A + B ⟶ C + D {\displaystyle {\ce {A + B -> C + D}}} Then: Rate = k ⋅ n ⋅ m {\displaystyle {\text{Rate}}=k\cdot ^{n}\cdot ^{m}} where n is the reaction order of A, m is the reaction order of B, n + m {\displaystyle n+m} is the reaction order of the full reaction, and k is the reaction constant.
{\displaystyle {\frac {d}{dt}}={\frac {d}{dt}}=-k.} The rate expression for an elementary bimolecular reaction is sometimes referred to as the Law of Mass Action as it was first proposed by Guldberg and Waage in 1864. An example of this type of reaction is a cycloaddition reaction.
For the reaction the observed rate equation (or rate expression) is: As for many reactions, the experimental rate equation does not simply reflect the stoichiometric coefficients in the overall reaction: It is third order overall: first order in H2 and second order in NO, even though the stoichiometric coefficients of both reactants are equal to 2.In chemical kinetics, the overall reaction rate is often explained using a mechanism consisting of a number of elementary steps. Not all of these steps affect the rate of reaction; normally the slowest elementary step controls the reaction rate. For this example, a possible mechanism is: Reactions 1 and 3 are very rapid compared to the second, so the slow reaction 2 is the rate-determining step. This is a bimolecular elementary reaction whose rate is given by the second-order equation: where k2 is the rate constant for the second step.
|
What type of compounds can form crystals?
|
[
"integral compounds",
"magnetic compounds",
"molecular compounds",
"ionic compounds"
] |
D
|
Many compounds form molecules, but ionic compounds form crystals instead. A crystal consists of many alternating positive and negative ions bonded together in a matrix. Look at the crystal of sodium chloride (NaCl) in the Figure below . The sodium and chloride ions are attracted to each other because they are oppositely charged, so they form ionic bonds.
Well formed crystals are rare. It has a Mohs hardness of 6.5 and a specific gravity of 2.9. It has a brittle fracture and no cleavage.
The compound forms yellowish-white hexagonal crystals.
Wells, A.F. (1958). The Structures of Crystals.
Unstable polymorphs more closely resemble the state in solution, and thus are kinetically advantaged. For example, out of hot water, metastable, fibrous crystals of benzamide appear first, only later to spontaneously convert to the more stable rhombic polymorph. Another example is magnesium carbonate, which more readily forms dolomite.
In materials science, a single crystal (or single-crystal solid or monocrystalline solid) is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries. The absence of the defects associated with grain boundaries can give monocrystals unique properties, particularly mechanical, optical and electrical, which can also be anisotropic, depending on the type of crystallographic structure. These properties, in addition to making some gems precious, are industrially used in technological applications, especially in optics and electronics.Because entropic effects favor the presence of some imperfections in the microstructure of solids, such as impurities, inhomogeneous strain and crystallographic defects such as dislocations, perfect single crystals of meaningful size are exceedingly rare in nature. The necessary laboratory conditions often add to the cost of production.
|
In grazing, a predator partially eats but does not kill what?
|
[
"prey",
"time",
"pack",
"predators"
] |
A
|
In grazing , the predator eats part of the prey but does not usually kill it. You may have seen cows grazing on grass. The grass they eat grows back, so there is no real effect on the population. In the ocean, kelp (a type of seaweed) can regrow after being eaten by fish.
Predators may be required to ensure that browsing and grazing animals are kept from over-breeding/over-feeding, destroying vegetation complexity, as may be concluded from mass-starvations which happened in Oostvaardersplassen. Some examples of these predators are Eurasian lynx and wolves. However, although it is generally undebated that predators occupy an important role in ecosystems, there is no general agreement about whether wild predators keep herbivore populations in check, or whether their influence is of more subtle nature (see Ecology of fear). By analogy, wildebeest populations in the Serengeti are primarily controlled by food constraints despite the presence of many predators. The consequence is natural mass-starvation.
When hunting, they wait on a perch until they spot prey. Then, they swoop down on prey or fly up to catch insects in flight. Sometimes, they chase prey on foot across the ground. The highly variable diet includes invertebrates and small vertebrates, which make up roughly one third and two thirds of the diet, respectively.
In predation, one organism, the predator, kills and eats another organism, its prey. Predators are adapted and often highly specialized for hunting, with acute senses such as vision, hearing, or smell. Many predatory animals, both vertebrate and invertebrate, have sharp claws or jaws to grip, kill, and cut up their prey. Other adaptations include stealth and aggressive mimicry that improve hunting efficiency.
It eats primarily eggs, small birds, small mammals, and lizards. Much of its prey is tracked down by scent and dug out of burrows, and although it is normally a slow, deliberate mover, it can move quite rapidly and pounce quickly when pursuing prey.
Prey availability varies more in grasslands than in river basins. In both habitats green anacondas have been found to feed on large prey, usually 14% to 50% of their own mass. Examples of prey include broad-snouted caimans, spectacled caimans, yacare caimans, black caimans, smooth-fronted caimans, wattled jacanas, capybaras, red-rumped agoutis, collared peccaries, South American tapirs, boa constrictors, brown-banded water snakes, green iguanas, cryptic golden tegus, scorpion mud turtles, gibba turtles, Arrau turtles, savanna side-necked turtles, red side-necked turtles, and northern pudús.Large prey occasionally causes serious injuries and death.
|
Bone tissues include compact bone, spongy bone, bone marrow, and?
|
[
"cartilage",
"esophagus",
"epithelium",
"periosteum"
] |
D
|
Bone tissues include compact bone, spongy bone, bone marrow, and periosteum.
The hollow tubular structure of bones provide considerable resistance against compression while staying lightweight. Most cells in bones are either osteoblasts, osteoclasts, or osteocytes.Bone tissue is a type of dense connective tissue. One of the types of tissue that makes up bone tissue is mineralized tissue and this gives it rigidity and a honeycomb-like three-dimensional internal structure.
Bone is metabolically active tissue composed of several types of cells. These cells include osteoblasts, which are involved in the creation and mineralization of bone tissue, osteocytes, and osteoclasts, which are involved in the reabsorption of bone tissue. Osteoblasts and osteocytes are derived from osteoprogenitor cells, but osteoclasts are derived from the same cells that differentiate to form macrophages and monocytes. Within the marrow of the bone there are also hematopoietic stem cells. These cells give rise to other cells, including white blood cells, red blood cells, and platelets.
Bone is a form of connective tissue found in the body, composed largely of hardened hydroxyapatite-containing collagen. In larger mammals, it is arranged in osteon regions. Bone matrix allows mineral salts such as calcium to be stored and provides protection for internal organs and support for locomotion.
Hematoxylin and eosin staining (H&E) shows that the cytoplasm of active osteoblasts is slightly basophilic due to the substantial presence of rough endoplasmic reticulum. The active osteoblast produces substantial collagen type I. About 10% of the bone matrix is collagen with the balance mineral. The osteoblast's nucleus is spherical and large.
The extracellular matrix of bone is laid down by osteoblasts, which secrete both collagen and ground substance. These synthesise collagen within the cell and then secrete collagen fibrils. The collagen fibers rapidly polymerise to form collagen strands. At this stage, they are not yet mineralised, and are called "osteoid".
|
What type of bacteria causes the disease called tuberculosis?
|
[
"mycobacterium",
"E. coli",
"staphylococcus",
"streptococcus"
] |
A
|
Tuberculosis (TB) is a common and often deadly disease caused by a genus of bacterium called Mycobacterium . Tuberculosis most commonly attacks the lungs but can also affect other parts of the body. TB is a chronic disease, but most people who become infected do not develop the full disease. Symptoms include a cough, which usually contains mucus and coughing up blood.
Mycobacterium tuberculosis (M. tb), also known as Koch's bacillus, is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coating on its cell surface primarily due to the presence of mycolic acid. This coating makes the cells impervious to Gram staining, and as a result, M. tuberculosis can appear weakly Gram-positive.
It can be spread within a hospital. The virulent and toxigenic strains produce an exotoxin formed by two polypeptide chains, which is itself produced when a bacterium is transformed by a gene from the β prophage.Several species cause disease in animals, most notably C. pseudotuberculosis, which causes the disease caseous lymphadenitis, and some are also pathogenic in humans. Some attack healthy hosts, while others tend to attack the immunocompromised.
Foamy macrophages are also found in diseases caused by pathogens that persist in the body, such as Chlamydia, Toxoplasma, or Mycobacterium tuberculosis. In tuberculosis (TB), bacterial lipids disable macrophages from pumping out excess LDL, causing them to turn into foam cells around the TB granulomas in the lung. The cholesterol forms a rich food source for the bacteria. As the macrophages die, the mass of cholesterol in the center of the granuloma becomes a cheesy substance called caseum.
A subclinical infection—sometimes called a preinfection or inapparent infection—is an infection by a pathogen that causes few or no signs or symptoms of infection in the host. Subclinical infections can occur in both humans and animals. Depending on the pathogen, which can be a virus or intestinal parasite, the host may be infectious and able to transmit the pathogen without ever developing symptoms; such a host is called an asymptomatic carrier. Many pathogens, including HIV, typhoid fever, and coronaviruses such as COVID-19 spread in their host populations through subclinical infection.Not all hosts of asymptomatic subclinical infections will become asymptomatic carriers. For example, hosts of Mycobacterium tuberculosis bacteria will only develop active tuberculosis in approximately one-tenth of cases; the majority of those infected by Mtb bacteria have latent tuberculosis, a non-infectious type of tuberculosis that does not produce symptoms in individuals with sufficient immune responses.Because subclinical infections often occur without eventual overt sign, in some cases their presence is only identified by microbiological culture or DNA techniques such as polymerase chain reaction (PCR) tests.
This TB strain found in Peru is different from that prevalent today in the Americas, which is more closely related to a later Eurasian strain likely brought by European colonists. However, this result is criticised by other experts from the field, for instance because there is evidence of the presence of Mycobacterium tuberculosis in 9,000 year old skeletal remains.Although relatively little is known about its frequency before the 19th century, its incidence is thought to have peaked between the end of the 18th century and the end of the 19th century. Over time, the various cultures of the world gave the illness different names: phthisis (Greek), consumptio (Latin), yaksma (India), and chaky oncay (Incan), each of which make reference to the "drying" or "consuming" effect of the illness, cachexia. In the 19th century, TB's high mortality rate among young and middle-aged adults and the surge of Romanticism, which stressed feeling over reason, caused many to refer to the disease as the "romantic disease".
|
Studies have shown that not only does reproduction have a cost as far as how long male fruit flies live, but also fruit flies that have already mated several times have limited amounts of this?
|
[
"dna",
"eggs",
"sperm",
"chromosomes"
] |
C
|
Energy Budgets, Reproductive Costs, and Sexual Selection in Drosophila Research into how animals allocate their energy resources for growth, maintenance, and reproduction has used a variety of experimental animal models. Some of this work has been done using the common fruit fly, Drosophila melanogaster. Studies have shown that not only does reproduction have a cost as far as how long male fruit flies live, but also fruit flies that have already mated several times have limited sperm remaining for reproduction. Fruit flies maximize their last chances at reproduction by selecting optimal mates. In a 1981 study, male fruit flies were placed in enclosures with either virgin or inseminated females. The males that mated with virgin females had shorter life spans than those in contact with the same number of inseminated females with which they were unable to mate. This effect occurred regardless of how large (indicative of their age) the males were. Thus, males that did not mate lived longer, allowing them more opportunities to find mates in the future. More recent studies, performed in 2006, show how males select the female with which they will mate and [3] how this is affected by previous matings (Figure 45.8). Males were allowed to select between smaller and larger females. Findings showed that larger females had greater fecundity, producing twice as many offspring per mating as the smaller females did. Males that had previously mated, and thus had lower supplies of sperm, were termed “resource-depleted,” while males that had not mated were termed “nonresource-depleted. ” The study showed that although non-resource-depleted males preferentially mated with larger females, this selection of partners was more pronounced in the resource-depleted males. Thus, males with depleted sperm supplies, which were limited in the number of times that they could mate before they replenished their sperm supply, selected larger, more fecund females, thus maximizing their chances for offspring. This study was one of the first to show that the physiological state of the male affected its mating behavior in a way that clearly maximizes its use of limited reproductive resources.
This has been supported in studies revealing the rapid evolution of SPF genes.In a study examining fruit flies under polygamous and monogamous conditions, it was discovered that antagonistic coevolution decreases in monogamy, as the organisms mate with only one opposite-sex member and there is no competition among males to mate with the female.In another laboratory study, a mutation that reduces the attractiveness of females was introduced into the genome of the experimental females. By reducing the attractiveness of the females expressing the trait, the mutation provided females with resistance to the direct costs of re-mating and male courtship. These results show that the resistance allele significantly accumulated in the experimental group, suggesting that the direct costs of male-courtship are greater than the indirect benefits of male-courtship.Reciprocal crosses of Drosophila melanogaster have been used to investigate the evolution of sexual traits under allopatric conditions.
Female adults are 4.75mm in length, males are slightly smaller. Both adults are mostly black in color with white stripes, orange-red eyes, and a single pair of clear wings with black banding. The adult female fly lays a single egg per blueberry, and when the larva hatches it consumes the fruit, usually finishing the entire berry in under 3 weeks and rendering it unmarketable.
Throughout 2012 and 2013, Gowaty, Kim, and Anderson repeated Bateman's experiment in its entirety, staying as close to Bateman's published methodology as possible. They found that upon combining certain fly strains with one another, the offspring were unable to survive to adulthood. Thus, Bateman's results regarding the number of individuals not having mated was too high. This was valid for both the males and females.Gowaty desired to further explore the reasoning behind the premature death of the Drosophila.
Drosophila bifurca is a species of fruit fly. Males of this species are known to have the longest sperm cells of any organism on Earth—5.8 cm long when uncoiled, over twenty times the entire body length of the male.The cells are mostly tail, and are delivered to the females in tangled coils. A male can only make a few hundred such cells during its lifetime. The other members of the genus Drosophila also make very few, giant sperm cells, with D. bifurca's being the longest. The sperm cells are produced in testes 6.7 cm long, which comprise 11% of the male's body mass. Males of the species become sexually mature 17 days after emergence, instead of 7 days for females, which suggests testes development is costly in time and energy.Such sperm gigantism is thought to have evolved via a Fisherian runaway process, with a genetic link between sperm length and the length of the female seminal receptacle (sperm-storage organ) length, combined with an increasing competitive advantage of longer sperm as the seminal receptacle evolves to be longer.
Most peaches and nectarines are self fertile and thus require fewer pollinators than apples and pears.
|
What are the two most common causes of diseases?
|
[
"bacteria and protazoa",
"viruses and protazoa",
"nutritional deficiencies",
"bacteria and viruses"
] |
D
|
Today most people realize that microorganisms, such as bacteria or viruses, are the cause of disease. This concept is known as the germ theory of disease, one of the few scientific theories in the field of the life sciences. Although it seems obvious now, people did not always understand the cause of disease. How does a theory such as this become established?.
Common diseases in this category include whooping cough or tuberculosis, HIV/AIDs, malaria, influenza (the flu), and mumps. As low-to-middle income countries continue to develop, the types of diseases that affecting populations within these countries shifts primarily from infectious diseases, such as diarrhea and pneumonia, to primarily non-communicable diseases, such as cardiovascular disease, cancer and obesity. This shift is increasingly being referred to as the risk transition.
In a few cases, only one cause exists: for example, the virus HHV-8 causes all Kaposi's sarcomas. However, with the help of cancer epidemiology techniques and information, it is possible to produce an estimate of a likely cause in many more situations. For example, lung cancer has several causes, including tobacco use and radon gas.
The leading cause of human death in developing countries is infectious disease. The leading causes in developed countries are atherosclerosis (heart disease and stroke), cancer, and other diseases related to obesity and aging. By an extremely wide margin, the largest unifying cause of death in the developed world is biological aging, leading to various complications known as aging-associated diseases. These conditions cause loss of homeostasis, leading to cardiac arrest, causing loss of oxygen and nutrient supply, causing irreversible deterioration of the brain and other tissues.
By contrast colds, influenza and rotavirus infections are usually a problem during the winter months. Other viruses, such as measles virus, caused outbreaks regularly every third year. In developing countries, viruses that cause respiratory and enteric infections are common throughout the year. Viruses carried by insects are a common cause of diseases in these settings. Zika and dengue viruses for example are transmitted by the female Aedes mosquitoes, which bite humans particularly during the mosquitoes' breeding season.
Fever, hepatomegaly, leucocytosis, coughing etc.
|
Organic compounds are defined as covalently bonded compounds containing carbon, excluding carbonates and what else?
|
[
"gases",
"oxides",
"crystals",
"acids"
] |
B
|
At one time in history, it was thought that only living things were capable of synthesizing the carbon-containing compounds present in cells. For that reason, the term organic was applied to those compounds. Eventually it was proved that carbon-containing compounds could be synthesized from inorganic substances, but the term organic has remained. Currently, organic compounds are defined as covalently bonded compounds containing carbon, excluding carbonates and oxides. By this definition, compounds such as carbon dioxide (CO 2 ) and sodium carbonate (Na 2 CO 3 ) are considered to be inorganic. Organic chemistry is the study of all organic compounds.
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.
Still, it is generally agreed upon that there are (at least) a few carbon-containing compounds that should not be considered organic. For instance, almost all authorities would require the exclusion of alloys that contain carbon, including steel (which contains cementite, Fe3C), as well as other metal and semimetal carbides (including "ionic" carbides, e.g, Al4C3 and CaC2 and "covalent" carbides, e.g. B4C and SiC, and graphite intercalation compounds, e.g. KC8). Other compounds and materials that are considered 'inorganic' by most authorities include: metal carbonates, simple oxides of carbon (CO, CO2, and arguably, C3O2), the allotropes of carbon, cyanide derivatives not containing an organic residue (e.g., KCN, (CN)2, BrCN, cyanate anion CNO−, etc.), and heavier analogs thereof (e.g., cyaphide anion CP−, CSe2, COS; although carbon disulfide CS2 is often classed as an organic solvent).
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as inorganic chemistry. Inorganic compounds comprise most of the Earth's crust, although the compositions of the deep mantle remain active areas of investigation.Some simple carbon compounds are often considered inorganic. Examples include the allotropes of carbon (graphite, diamond, buckminsterfullerene, etc.), carbon monoxide, carbon dioxide, carbides, and the following salts of inorganic anions: carbonates, cyanides, cyanates, and thiocyanates. Many of these are normal parts of mostly organic systems, including organisms; describing a chemical as inorganic does not necessarily mean that it does not occur within living things.
organic chemistry The branch of chemistry concerned with the chemical properties and reactions of organic compounds. Contrast inorganic chemistry. organic compound Any chemical compound that contains one or more carbon atoms.
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.
|
What drives the turbine in a thermonuclear reactor?
|
[
"magnets",
"heated oil",
"heated water or steam",
"wind energy"
] |
C
|
Scientists are searching for ways to create controlled nuclear fusion reactions on Earth. Their goal is develop nuclear fusion power plants, where the energy from fusion of hydrogen nuclei can be converted to electricity. You can see how this might work in the Figure below . In the thermonuclear reactor, radiation from fusion is used to heat water and produce steam. The steam can then be used to turn a turbine and generate electricity.
The remaining stages do not need cooling. In the first stage, the turbine is largely an impulse turbine (similar to a pelton wheel) and rotates because of the impact of the hot gas stream. Later stages are convergent ducts that accelerate the gas. Energy is transferred into the shaft through momentum exchange in the opposite way to energy transfer in the compressor. The power developed by the turbine drives the compressor and accessories, like fuel, oil, and hydraulic pumps that are driven by the accessory gearbox.
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.
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.
The fuel is assembled into rods housed in a steel vessel that is submerged in water. The nuclear fission causes the water to boil, generating steam. This steam flows through pipes into turbines.
The turbine section (also called the "hot side" or "exhaust side" of the turbo) is where the rotational force is produced, in order to power the compressor (via a rotating shaft through the center of a turbo). After the exhaust has spun the turbine it continues into the exhaust and out of the vehicle. The turbine uses a series of blades to convert kinetic energy from the flow of exhaust gases to mechanical energy of a rotating shaft (which is used to power the compressor section). The turbine housings direct the gas flow through the turbine section, and the turbine itself can spin at speeds of up to 250,000 rpm.
|
What is the term for physicians and scientists who research and develop vaccines and treat and study conditions ranging from allergies to aids?
|
[
"immunologists",
"endocrinologists",
"vaccinologists",
"virologists"
] |
A
|
Immunologist The variations in peripheral proteins and carbohydrates that affect a cell’s recognition sites are of prime interest in immunology. These changes are taken into consideration in vaccine development. Many infectious diseases, such as smallpox, polio, diphtheria, and tetanus, were conquered by the use of vaccines. Immunologists are the physicians and scientists who research and develop vaccines, as well as treat and study allergies or other immune problems. Some immunologists study and treat autoimmune problems (diseases in which a person’s immune system attacks his or her own cells or tissues, such as lupus) and immunodeficiencies, whether acquired (such as acquired immunodeficiency syndrome, or AIDS) or hereditary (such as severe combined immunodeficiency, or SCID). Immunologists are called in to help treat organ transplantation patients, who must have their immune systems suppressed so that their bodies will not reject a transplanted organ. Some immunologists work to understand natural immunity and the effects of a person’s environment on it. Others work on questions about how the immune system affects diseases such as cancer. In the past, the importance of having a healthy immune system in preventing cancer was not at all understood. To work as an immunologist, a PhD or MD is required. In addition, immunologists undertake at least 2–3 years of training in an accredited program and must pass an examination given by the American Board of Allergy and Immunology. Immunologists must possess knowledge of the functions of the human body as they relate to issues beyond immunization, and knowledge of pharmacology and medical technology, such as medications, therapies, test materials, and surgical procedures.
Clinical pathology is a medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids such as blood and urine, as well as tissues, using the tools of chemistry, clinical microbiology, hematology and molecular pathology. Clinical pathologists work in close collaboration with medical technologists, hospital administrations, and referring physicians. Clinical pathologists learn to administer a number of visual and microscopic tests and an especially large variety of tests of the biophysical properties of tissue samples involving automated analysers and cultures. Sometimes the general term "laboratory medicine specialist" is used to refer to those working in clinical pathology, including medical doctors, Ph.D.s and doctors of pharmacology. Immunopathology, the study of an organism's immune response to infection, is sometimes considered to fall within the domain of clinical pathology.
Since the 19th century, communicable diseases came to be viewed as being caused by germs/microbes. The modern word "immunity" derives from the Latin immunis, meaning exemption from military service, tax payments or other public services.The first scientist who developed a full theory of immunity was Ilya Mechnikov who revealed phagocytosis in 1882.
With the increasing circulation of mass media and little content review in medical journals, almost anyone with or without proper education could publish a potential cure for disease. Actual practicing medical professionals also had to compete with the ever expanding pharmacy companies that were all too ready to provide new elixirs and promising treatments for the epidemics of the time.Emerging from the medical chaos were legitimate and life changing treatments. The late 19th century was the beginning of widespread use of vaccines.
Global Health Council - Member. Immunisation Coalition (Australia) - Sponsor. Innovative Medicines Canada - Member.
Centers for Disease Control and Prevention (CDC) and a CDC task force was formed to monitor the outbreak.In the early days, the CDC did not have an official name for the disease, often referring to it by way of diseases associated with it, such as lymphadenopathy, the disease after which the discoverers of HIV originally named the virus. They also used Kaposi's sarcoma and opportunistic infections, the name by which a task force had been set up in 1981. At one point the CDC referred to it as the "4H disease", as the syndrome seemed to affect heroin users, homosexuals, hemophiliacs, and Haitians.
|
Where are temperatures the lowest?
|
[
"over the oceans",
"at the equator",
"in asia",
"at the poles"
] |
D
|
At the poles, the Sun’s rays are least direct. Much of the area is covered with ice and snow, which reflect a lot of sunlight. Temperatures are lowest here.
In the most marine of those areas affected by this regime, temperatures above 20 °C (68 °F) are extreme weather events, even in the midst of summer. Temperatures above 30 °C (86 °F) have been recorded on rare occasions in some areas of this climate, and in winter temperatures down to −20 °C (−4 °F) have seldom been recorded in some areas.
Based on the Köppen climate classification, the peak is located in an alpine subarctic climate zone with long, cold, snowy winters, and cool to warm summers. Temperatures can drop below −10 °F with wind chill factors below −30 °F.
All maps use the ≥0 °C (or >-3 °C) definition for temperate climates, the 18 °C annual mean temperature threshold to distinguish between hot and cold dry climates, and solely 18 °C for tropical climates.
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.
Since the tropopause responds to the average temperature of the entire layer that lies underneath it, it is at its maximum levels over the Equator, and reaches minimum heights over the poles. On account of this, the coolest layer in the atmosphere lies at about 17 km over the equator. Due to the variation in starting height, the tropopause extremes are referred to as the equatorial tropopause and the polar tropopause.
|
Protecting the surface of metal prevents what?
|
[
"extraction",
"diffusion",
"corrosion",
"evaporation"
] |
C
|
One way to prevent corrosion is to protect the surface of the metal. Covering the surface of the metal object with paint or oil will prevent corrosion by not allowing oxygen to contact it. Unfortunately, scratches in the paint or wearing off of the oil will allow the corrosion to begin. Corrosion-sensitive metals can also be coated with another metal that is resistant to corrosion. A “tin can” is actually made of iron coated with a thin layer of tin which protects the iron.
Protective Coatings: Applying a protective coating or barrier can help prevent corrosive substances from coming into contact with the metal surface, thus reducing the likelihood of SCC. For example, using an epoxy coating on the interior surface of a pipeline can reduce the likelihood of SCC. Cathodic Protection: Cathodic protection is a technique used to protect metals from corrosion by applying a small electrical current to the metal surface.
N.B. Pilling and R.E. Bedworth suggested in 1923 that metals can be classed into two categories: those that form protective oxides, and those that cannot. They ascribed the protectiveness of the oxide to the volume the oxide takes in comparison to the volume of the metal used to produce this oxide in a corrosion process in dry air. The oxide layer would be unprotective if the ratio is less than unity because the film that forms on the metal surface is porous and/or cracked. Conversely, the metals with the ratio higher than 1 tend to be protective because they form an effective barrier that prevents the gas from further oxidizing the metal.
This is rather a simplified view of the corrosion process, because it can occur in several different forms.Prevention of corrosion by cathodic protection (CP) works by introducing another metal (the galvanic anode) with a much more anodic surface, so that all the current will flow from the introduced anode and the metal to be protected becomes cathodic in comparison to the anode. This effectively stops the oxidation reactions on the metal surface by transferring them to the galvanic anode, which will be sacrificed in favour of the structure under protection. More simply put, this takes advantage of the relatively low stability of magnesium, aluminum or zinc metals; they dissolve instead of iron because their bonding is weaker compared to iron, which is bonded strongly via its partially filled d-orbitals. For this protection to work there must be an electron pathway between the anode and the metal to be protected (e.g., a wire or direct contact) and an ion pathway between both the oxidizing agent (e.g., oxygen and water or moist soil) and the anode, and the oxidizing agent and the metal to be protected, thus forming a closed circuit; therefore simply bolting a piece of active metal such as zinc to a less active metal, such as mild steel, in air (a poor ionic conductor) will not furnish any protection.
This tends to use more noble metals that resist corrosion better. Chrome, nickel, silver and gold can all be used. Galvanizing with zinc protects the steel base metal by sacrificial anodic action.
Metallic substrates are often chosen for their advantageous metallic properties, such as withstanding high temperatures and transferring heat faster. They can be subject to corrosion.
|
What type of tissues are major barriers to the entry of pathogens into the body?
|
[
"skin",
"vascular",
"mucosal",
"nasal"
] |
C
|
The Mucosal Immune Response Mucosal tissues are major barriers to the entry of pathogens into the body. The IgA (and sometimes IgM) antibodies in mucus and other secretions can bind to the pathogen, and in the cases of many viruses and bacteria, neutralize them. Neutralization is the process of coating a pathogen with antibodies, making it physically impossible for the pathogen to bind to receptors. Neutralization, which occurs in the blood, lymph, and other body fluids and secretions, protects the body constantly. Neutralizing antibodies are the basis for the disease protection offered by vaccines. Vaccinations for diseases that commonly enter the body via mucous membranes, such as influenza, are usually formulated to enhance IgA production. Immune responses in some mucosal tissues such as the Peyer’s patches (see Figure 21.11) in the small intestine take up particulate antigens by specialized cells known as microfold or M cells (Figure 21.27). These cells allow the body to sample potential pathogens from the intestinal lumen. Dendritic cells then take the antigen to the regional lymph nodes, where an immune response is mounted.
The organism enters directly through the breakdown of mechanical defense barriers such as mucosa or skin. Conditions which lead to the development of an immunocompromised state make the patient more susceptible to ecthyma gangrenosum and sepsis. In case of sepsis, the bacteria reaches the skin via the bloodstream.
The main cell types are fibroblasts, macrophages and adipocytes (the subcutaneous tissue contains 50% of body fat). Fat serves as padding and insulation for the body. Microorganisms like Staphylococcus epidermis colonize the skin surface. The density of skin flora depends on region of the skin. The disinfected skin surface gets recolonized from bacteria residing in the deeper areas of the hair follicle, gut and urogenital openings.
Concentration differential between tissues. Exchange surface. Presence of natural barriers.
There are mechanical, chemical, and biological factors affecting the effectiveness and results of the non-specific immune response. These factors include the epithelial surfaces forming a physical barrier, fatty acids that inhibit the growth of bacteria, and the microflora of the gastrointestinal tract serving to prevent the colonization of pathogenic bacteria. The non-specific immune system involves cells to which antigens are not specific in regards to fighting infection. The non-specific immune cells mentioned above (macrophages, neutrophils, and dendritic cells) will be discussed regarding their immediate response to infection.
After entering a host's body (which marks the beginning of the infection process), pathogens usually require time to multiply or replicate at their favorite site in the body (for example, the Hepatitis virus multiplies in the liver). After a certain time period, the pathogens become numerous enough so that the host is now able to transmit them into the environment. This marks the end of the latent period (pre-infectious period) and simultaneously the beginning of the infectious period.
|
Trash that gets into fresh and saltwater waterways is called what type of debris?
|
[
"aquatic",
"pollution",
"ocean",
"water"
] |
A
|
Most protists consist of a single cell. Some are multicellular but they lack specialized cells.
In saltwater bodies, organic material breaks down and forms a marine snow. This example of detritus commonly consists of organic materials such as dead phytoplankton and zooplankton, the outer walls of diatoms and coccolithophores, dead skin and scales of fish, and fecal pellets. This material will slowly sink to the seafloor, where it makes up the majority of sediment in some areas. Once settled, the material will not only contribute to sediments but will help to feed different species of detritivore, organisms which feed on detritus, such as annelid worms and sea cucumbers, to name a few. The exact composition of this detritus varies based on location and time of year, as it is very closely tied to primary production.
Discarded or lost fishing gear, including plastic monofilament line and nylon netting (sometimes called ghost nets), is typically neutrally buoyant and can, therefore, drift at variable depths within the oceans. Various countries have reported that microplastics from the industry and other sources have been accumulating in different types of seafood. In Indonesia, 55% of all fish species had evidence of manufactured debris similar to America which reported 67%.
The transportation is affected by their inherent characteristics (texture and shape) but also environmental factors such as flow velocity, matrix type and seasonal variability. Numerical models are able to trace small plastic debris (micro- and meso-plastics) drifting in the ocean, thus predicting their fate. Some microplastics leave the sea and enter the air, as researchers from the University of Strathclyde discovered in 2020.
Through this process of eating the detritus many times over and harvesting the microorganisms from it, the detritus thins out, becomes fractured and becomes easier for the microorganisms to use, and so the complex carbohydrates are also steadily broken down and disappear over time. What is left behind by the detritivores is then further broken down and recycled by decomposers, such as bacteria and fungi. This detritus cycle plays a large part in the so-called purification process, whereby organic materials carried in by rivers is broken down and disappears, and an extremely important part in the breeding and growth of marine resources. In ecosystems on land, far more essential material is broken down as dead material passing through the detritus chain than is broken down by being eaten by animals in a living state. In both land and aquatic ecosystems, the role played by detritus is too large to ignore.
For example, the tsunami in Japan in 2011 produced huge amounts of debris: estimates of 5 million tonnes of waste were reported by the Japanese Ministry of the Environment. Some of this waste, mostly plastic and styrofoam washed up on the coasts of Canada and the United States in late 2011. Along the west coast of the United States, this increased the amount of litter by a factor of 10 and may have transported alien species.
|
What is the term for genes that control the expression of other genes within specific regions of cells in the developing organism?
|
[
"expression genes",
"age genes",
"data genes",
"gap genes"
] |
D
|
Gap genes control the expression of other genes within specific regions of cells in the developing organism. This allows specific genes to be expressed in certain cells at the appropriate stage of development.
Regulation of gene expression is the control of the amount and timing of appearance of the functional product of a gene. Control of expression is vital to allow a cell to produce the gene products it needs when it needs them; in turn, this gives cells the flexibility to adapt to a variable environment, external signals, damage to the cell, and other stimuli. More generally, gene regulation gives the cell control over all structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism. Numerous terms are used to describe types of genes depending on how they are regulated; these include: A constitutive gene is a gene that is transcribed continually as opposed to a facultative gene, which is only transcribed when needed.
Eukaryotes have a much larger genome and thus have different methods of gene regulation than in prokaryotes. All cells in a eukaryotic organism have the same DNA but are specified through differential gene expression, a phenomenon known as genetic totipotency. However, in order for a cell to express the genes for proper functioning, the genes must be closely regulated to express the correct properties. Genes in eukaryotes are controlled on the transcriptional, post-transcriptional, translational, and post-translational levels. On the transcriptional level, gene expression is regulated by altering transcription rates. Genes that encode proteins include exons which will encode the polypeptides, introns that are removed from mRNA before the translation of proteins, a transcriptional start site in which RNA polymerase binds, and a promoter.
Differences in gene expression are especially clear within multicellular organisms, where cells all contain the same genome but have very different structures and behaviors due to the expression of different sets of genes. All the cells in a multicellular organism derive from a single cell, differentiating into variant cell types in response to external and intercellular signals and gradually establishing different patterns of gene expression to create different behaviors. As no single gene is responsible for the development of structures within multicellular organisms, these patterns arise from the complex interactions between many cells.Within eukaryotes, there exist structural features of chromatin that influence the transcription of genes, often in the form of modifications to DNA and chromatin that are stably inherited by daughter cells.
Expression of certain genes, for example, those coding for pilus expression in E. coli, is regulated by the methylation of GATC sites in the promoter region of the gene operon. The cells' environmental conditions just after DNA replication determine whether Dam is blocked from methylating a region proximal to or distal from the promoter region. Once the pattern of methylation has been created, the pilus gene transcription is locked in the on or off position until the DNA is again replicated.
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.
|
In vertebrates, what tissue is a type of connective tissue that supports the entire body structure?
|
[
"cartilage",
"blood",
"collagen",
"bone"
] |
D
|
Complex Tissue Structure As multicellular organisms, animals differ from plants and fungi because their cells don’t have cell walls, their cells may be embedded in an extracellular matrix (such as bone, skin, or connective tissue), and their cells have unique structures for intercellular communication (such as gap junctions). In addition, animals possess unique tissues, absent in fungi and plants, which allow coordination (nerve tissue) of motility (muscle tissue). Animals are also characterized by specialized connective tissues that provide structural support for cells and organs. This connective tissue constitutes the extracellular surroundings of cells and is made up of organic and inorganic materials. In vertebrates, bone tissue is a type of connective tissue that supports the entire body structure. The complex bodies and activities of vertebrates demand such supportive tissues. Epithelial tissues cover, line, protect, and secrete. Epithelial tissues include the epidermis of the integument, the lining of the digestive tract and trachea, and make up the ducts of the liver and glands of advanced animals. The animal kingdom is divided into Parazoa (sponges) and Eumetazoa (all other animals). As very simple animals, the organisms in group Parazoa (“beside animal”) do not contain true specialized tissues; although they do possess specialized cells that perform different functions, those cells are not organized into tissues. These organisms are considered animals since they lack the ability to make their own food. Animals with true tissues are in the group Eumetazoa (“true animals”). When we think of animals, we usually think of Eumetazoans, since most animals fall into this category. The different types of tissues in true animals are responsible for carrying out specific functions for the organism. This differentiation and specialization of tissues is part of what allows for such incredible animal diversity. For example, the evolution of nerve tissues and muscle tissues has resulted in animals’ unique ability to rapidly sense and respond to changes.
The hollow tubular structure of bones provide considerable resistance against compression while staying lightweight. Most cells in bones are either osteoblasts, osteoclasts, or osteocytes.Bone tissue is a type of dense connective tissue. One of the types of tissue that makes up bone tissue is mineralized tissue and this gives it rigidity and a honeycomb-like three-dimensional internal structure.
Fibromuscular tissue is made up of fibrous tissue and muscular tissue. New vascularised connective tissue that forms in the process of wound healing is termed granulation tissue. All of the special connective tissue types have been included as a subset of fascia in the fascial system, with blood and lymph classed as liquid fascia.Bone and cartilage can be further classified as supportive connective tissue. Blood and lymph can also be categorized as fluid connective tissue, and liquid fascia.
A connective tissue disease (collagenosis) is any disease that has the connective tissues of the body as a target of pathology. Connective tissue is any type of biological tissue with an extensive extracellular matrix that supports, binds together, and protects organs. These tissues form a framework, or matrix, for the body, and are composed of two major structural protein molecules: collagen and elastin. There are many different types of collagen protein in each of the body's tissues.
Bone is a form of connective tissue found in the body, composed largely of hardened hydroxyapatite-containing collagen. In larger mammals, it is arranged in osteon regions. Bone matrix allows mineral salts such as calcium to be stored and provides protection for internal organs and support for locomotion.
The cardiac skeleton is made of dense connective tissue which gives structure to the heart by forming the atrioventricular septum—which separates the atria from the ventricles—and the fibrous rings which serve as bases for the four heart valves. Collagen extensions from the valve rings seal and limit electrical activity of the atria from influencing electrical pathways that cross the ventricles.
|
Red blood cells don't have a nucleus. this allows them to do what?
|
[
"be redder",
"move faster",
"heal faster",
"carry more oxygen"
] |
D
|
Red blood cells ( Figure below ) are made in the red marrow of long bones, rib bones, the skull, and vertebrae. Each red blood cell lives for only 120 days (about four months). After this time, they are destroyed in the liver and spleen. Mature red blood cells do not have a nucleus or other organelles. Lacking these components allows the cells to have more hemoglobin and carry more oxygen.
In adults, the majority of hematopoiesis occurs in the bone marrow. Significant production in any other organ is usually the result of a pathological process. When red blood cell (RBC) numbers are low, the body induces a homeostatic mechanism aimed to increase the synthesis of RBCs, typically via the production of erythropoietin.
Under the microscope, normal red blood cells (RBCs) appear as small concave discs. Their numbers are reported per high-power field. In highly concentrated urine they may shrivel and develop a spiky shape, which is termed crenation, while in dilute urine they can swell and lose their hemoglobin, creating a faint outline known as a ghost cell.
Bone marrow failure occurs in individuals who produce an insufficient amount of red blood cells, white blood cells or platelets. Red blood cells transport oxygen to be distributed throughout the body's tissue. White blood cells fight off infections that enter the body. Bone marrow also contains platelets, which trigger clotting, and thus help stop the blood flow when a wound occurs.
Hemolysis is sometimes called hematolysis, erythrolysis, or erythrocytolysis. The words hemolysis () and hematolysis () both use combining forms conveying the idea of "lysis of blood" (hemo- or hemato- + -lysis). The words erythrolysis () and erythrocytolysis () both use combining forms conveying the idea of "lysis of erythrocytes" (erythro- ± cyto- + -lysis). Red blood cells (erythrocytes) have a short lifespan (approximately 120 days), and old (senescent) cells are constantly removed and replaced with new ones via erythropoiesis.
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 number of electron pairs that hold two atoms together is called?
|
[
"bond order",
"nuclear order",
"proton order",
"electron order"
] |
A
|
Summary Bond order is the number of electron pairs that hold two atoms together. Single bonds have a bond order of one, and multiple bonds with bond orders of two (a double bond) and three (a triple bond) are quite common. In closely related compounds with bonds between the same kinds of atoms, the bond with the highest bond order is both the shortest and the strongest. In bonds with the same bond order between different atoms, trends are observed that, with few exceptions, result in the strongest single bonds being formed between the smallest atoms. Tabulated values of average bond energies can be used to calculate the enthalpy change of many chemical reactions. If the bonds in the products are stronger than those in the reactants, the reaction is exothermic and vice versa. Saylor URL: http://www. saylor. org/books.
Two electrons fill the lower-energy bonding orbital, σg(1s), while the remaining two fill the higher-energy antibonding orbital, σu*(1s). Thus, the resulting electron density around the molecule does not support the formation of a bond between the two atoms; without a stable bond holding the atoms together, the molecule would not be expected to exist. Another way of looking at it is that there are two bonding electrons and two antibonding electrons; therefore, the bond order is 0 and no bond exists (the molecule has one bound state supported by the Van der Waals potential).
For example, Fe(CO)3 provides 2 electrons. The derivation of this is briefly as follows: Fe has 8 valence electrons. Each carbonyl group is a net 2 electron donor after the internal σ- and π-bonding are taken into account making 14 electrons. 3 pairs are considered to be involved in Fe–CO σ-bonding and 3 pairs are involved in π-backbonding from Fe to CO reducing the 14 to 2.
The small atomic radii of carbon, nitrogen, and oxygen facilitate the formation of double or triple bonds.While it would normally be expected that hydrogen and helium, on electron configuration consistency grounds, would be located atop the s-block elements, the first row anomaly in these two elements is strong enough to warrant alternative placements. Hydrogen is occasionally positioned over fluorine, in group 17, rather than over lithium in group 1. Helium is regularly positioned over neon, in group 18, rather than over beryllium in group 2.
This corresponds to the electronic structure of the second excited state of O2 (1Σg+ state), and also corresponds to the (incorrect) Lewis structure of the ground state of O2. Thus, a comparison of the magnitude of the inter-electronic repulsions in a series of possible molecular structures can be used to assess their relative energies and hence determine the ground and excited states. Additionally, it is found that in all three electronic structures, the net bond order is 2 as they all have four electrons in the spatial region between the oxygen nuclei. Thus, we see that this example clearly demonstrates that “not all double bonds are created equal”.
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.
|
What occurs when the immune system makes an inflammatory response to a harmless antigen?
|
[
"antibodies",
"asthma attack",
"allergies",
"immunity"
] |
C
|
Allergies occur when the immune system makes an inflammatory response to a harmless antigen. An antigen that causes an allergy is called an allergen.
Inflammation is one of the first responses of the immune system to infection or irritation. The response is stimulated by chemical factors released by injured cells. These chemical factors induce all associated inflammatory symptoms by sensitizing pain receptors, causing vasodilation of the blood vessels at the scene, and attracting phagocytes.Neutrophils are the first to the scene, triggering other parts of the immune system by releasing factors to summon other leukocytes and lymphocytes. Other innate leukocytes include natural killer cells, mast cells, eosinophils, basophils, macrophages, and dendritic cells.
The immune system recognizes foreign pathogens and eliminates them. This occurs in several phases. In the early inflammation phase, the pathogens are recognized by antibodies that are already present (innate or acquired through prior infection; see also cross-reactivity). Immune-system components (e.g. complement) are bound to the antibodies and kept near, in reserve to disable them via phagocytosis by scavenger cells (e.g. macrophages).
A unique feature of T cells is their ability to discriminate between healthy and abnormal (e.g. infected or cancerous) cells in the body. Healthy cells typically express a large number of self derived pMHC on their cell surface and although the T cell antigen receptor can interact with at least a subset of these self pMHC, the T cell generally ignores these healthy cells. However, when these very same cells contain even minute quantities of pathogen derived pMHC, T cells are able to become activated and initiate immune responses. The ability of T cells to ignore healthy cells but respond when these same cells contain pathogen (or cancer) derived pMHC is known as antigen discrimination. The molecular mechanisms that underlie this process are controversial.
There are mechanical, chemical, and biological factors affecting the effectiveness and results of the non-specific immune response. These factors include the epithelial surfaces forming a physical barrier, fatty acids that inhibit the growth of bacteria, and the microflora of the gastrointestinal tract serving to prevent the colonization of pathogenic bacteria. The non-specific immune system involves cells to which antigens are not specific in regards to fighting infection. The non-specific immune cells mentioned above (macrophages, neutrophils, and dendritic cells) will be discussed regarding their immediate response to infection.
Inflammatory abnormalities are a large group of disorders that underlie a vast variety of human diseases. The immune system is often involved with inflammatory disorders, as demonstrated in both allergic reactions and some myopathies, with many immune system disorders resulting in abnormal inflammation. Non-immune diseases with causal origins in inflammatory processes include cancer, atherosclerosis, and ischemic heart disease.Examples of disorders associated with inflammation include:
|
What energy source, now making a comeback, has helped propel ships and pump water for many years?
|
[
"weather energy",
"geothermal energy",
"solar energy",
"wind energy"
] |
D
|
The whirring blades of these wind turbines look stark against the darkening sky at sunset. The energy of the wind causes the blades to spin, and the energy of the spinning blades is used to generate electricity. People have been using wind for energy for centuries. Until about 200 years ago, for example, ships depended on wind to sail the oceans. And windmills have long been used to gather wind energy to pump water and do other useful work. Today, wind energy is making a comeback. Do you know why? What might be advantages of using the wind for energy? This chapter has the answers.
Fluid Power: Hydraulic and pneumatic systems use electrically driven pumps to drive water or air respectively into cylinders to power linear movement. Electrochemical: Chemicals and materials can also be sources of power. They may chemically deplete or need re-charging, as is the case with batteries, or they may produce power without changing their state, which is the case for solar cells and thermoelectric generators.
Among the first studies to evaluate the water and energy relationship was a life-cycle analysis conducted by Peter Gleick in 1994 that highlighted the interdependence and initiated the joint study of water and energy. In 2014 the US Department of Energy (DOE) released their report on the water-energy nexus citing the need for joint water-energy policies and better understanding of the nexus and its susceptibility to climate change as a matter of national security. The hybrid Sankey diagram in the DOE's 2014 water-energy nexus report summarizes water and energy flows in the US by sector, demonstrating interdependence as well as singling out thermoelectric power as the single largest user of water, used mainly for cooling.
Petroleum fuels. This includes diesel, jet fuel, and kerosene.
Russian aicraft carrier Admiral Kuznetsov), because of needs of high power and speed, although from 1970s they were mostly replaced by gas turbines. Large naval vessels and submarines continue to be operated with steam turbines, using nuclear reactors to boil the water.
Gruen performed heat pump technology research including a solar powered heat pump. This technology is commercialized and is currently being used for hydrogen “getters,” which absorb hydrogen produced in various industrial processes.
|
What is it called when the nucleus of an atom splits into two smaller nuclei?
|
[
"complex fission",
"cell division",
"nuclear fusion",
"nuclear fission"
] |
D
|
Nuclear fission is the splitting of the nucleus of an atom into two smaller nuclei. This releases a great deal of energy. Nuclear power plants use the energy from nuclear fission to generate electricity.
Atomic energy or energy of atoms is energy carried by atoms. The term originated in 1903 when Ernest Rutherford began to speak of the possibility of atomic energy. H. G. Wells popularized the phrase "splitting the atom", before discovery of the atomic nucleus. Atomic energy includes: Nuclear binding energy, the energy required to split a nucleus of an atom.
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.
Understanding the structure of the atomic nucleus is one of the central challenges in nuclear physics.
There are two ways in which the two-proton emission may proceed. The neon nucleus might eject a "diproton"—a pair of protons bundled together as a 2He nucleus—which then decays into separate protons.
|
The curie (ci) is one measure of the rate of what?
|
[
"spin",
"division",
"decay",
"growth"
] |
C
|
The curie (Ci) is one measure of the rate of decay (named after Pierre and Marie Curie). One curie is equivalent to 3.7 × 10 10 disintegrations per second. Since this is obviously a large and unwieldy number, radiation is often expressed in millicuries or microcuries (still very large numbers). Another measure is the becquerel (Bq) , named after Henri Becquerel. The becquerel is defined as an activity of one disintegration/second. Both of these units are concerned with the disintegration rate of the radioactive isotope and give no indication of dosage to the target material.
One becquerel (Bq) is equal to one disintegration per second; 1 becquerel (Bq) is equal to 60 dpm. One curie (Ci) an old non-SI unit is equal to 3.7×1010 Bq or dps, which is equal to 2.22×1012 dpm. == References ==
In a Frame Relay network, committed information rate (CIR) is the bandwidth for a virtual circuit guaranteed by an internet service provider to work under normal conditions. Committed data rate (CDR) is the payload portion of the CIR.At any given time, the available bandwidth should not fall below this committed figure. The bandwidth is usually expressed in kilobits per second (kbit/s). Above the CIR, an allowance of burstable bandwidth is often given, whose value can be expressed in terms of an additional rate, known as the excess information rate (EIR), or as its absolute value, peak information rate (PIR).
These plots show the predicted CPAM countrate responses for these parameter settings: Detection efficiency, 0.2; Flowrate, 5 cubic feet per minute (cfm); Collection efficiency, 0.7; Constant concentration, 1E-09 μ {\displaystyle \mu } Ci/cc; Rectangular window length, 2 inches; Circular window radius, 1 inch; Media (tape) speed, 1 inch/hour. The concentration instantly steps up to its constant value when the time reaches 30 minutes, and there is a 100 count per minute (cpm) constant background. Note: A microcurie ( μ {\displaystyle \mu } Ci) is a measure of the disintegration rate, or activity, of a radioactive source; it is 2.22E06 disintegrations per minute. In the LL plot, note that the FF countrate continues to increase.
Typically this is measured at the chip surface ca. 10–20%.
They correspond to the oldest measurements. Without taking them into account, the confidence interval obtained in ns is: 8<τB<12.3. For state C, the dispersion is more important.
|
A unique type of organism is also known as what?
|
[
"taxonomy",
"species",
"parasites",
"element"
] |
B
|
A species is a unique type of organism. Members of a species can interbreed and produce offspring that can breed (they are fertile). Organisms that are not in the same species cannot do this. Examples of species include humans, lions, and redwood trees. Can you name other examples?.
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 ==
Microorganisms are diverse and include all bacteria and archaea, most protists including algae, protozoa and fungal-like protists, as well as certain microscopic animals such as rotifers. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses as microorganisms, but others consider these as non-living.Microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers.
There are many other popular phylogenetic exercises that use different sets of ‘organisms’, some of which were inspired by the Caminalcule exercises. Potential alternative data sets include sets of twigs, chocolate bars, Chinese masks, and dragons.
A type species is both a concept and a practical system that is used in the classification and nomenclature (naming) of animals. The "type species" represents the reference species and thus "definition" for a particular genus name. Whenever a taxon containing multiple species must be divided into more than one genus, the type species automatically assigns the name of the original taxon to one of the resulting new taxa, the one that includes the type species. The term "type species" is regulated in zoological nomenclature by article 42.3 of the International Code of Zoological Nomenclature, which defines a type species as the name-bearing type of the name of a genus or subgenus (a "genus-group name").
Involving evolutionary physiology and environmental physiology, comparative physiology considers the diversity of functional characteristics across organisms.
|
Snakes use what anatomical structure to smell scents in the air?
|
[
"forked tails",
"branched tongue",
"forked tongue",
"forked eyes"
] |
C
|
Most reptiles have good eyesight and a keen sense of smell. Snakes smell scents in the air using their forked tongue (see Figure below ). This helps them locate prey. Some snakes have heat-sensing organs on their head that help them find endothermic prey, such as small mammals and birds. Staring into the Beautiful Cold-Blooded Eyes of Reptiles at http://www. environmentalgraffiti. com/news-reptile-eyes is a pictorial display of numerous reptile eyes.
Conflicting evidence, however, was produced when pigeons were housed in open cages and exposed to a fan produced air current carrying the scent of benzaldehyde. When released with exposure only to the natural air during transport and at the release site, both experimentals and controls were homeward oriented. Contrary if their response were simply to wind direction. A consistent feature of the olfaction experiments is that anosmic pigeons that are released from familiar sites are essentially unaffected. Perhaps a common fault of the olfactory mosaic and gradient model of olfactory navigation is that each model is over simplistic and that they do not sufficiently take account of other cues that may be of importance.
Swamp eels, which are not true eels, can absorb oxygen through their highly vascularized mouths and pharynges, and in some cases (e.g., Monopterus rongsaw) through their skin. Snakehead fish (Channidae): This family of fish consists of obligate air breathers, using their branchial arch, which are a primitive labyrinth organ. The northern snakehead of Eastern Asia can "walk" on land by wriggling and using its pectoral fins, which allows it to move between the slow-moving, and often stagnant and temporary bodies of water in which it lives.
The ocelli are concerned in the detection of changes in light intensity, enabling the fly to react swiftly to the approach of an object.Like other insects, flies have chemoreceptors that detect smell and taste, and mechanoreceptors that respond to touch. The third segments of the antennae and the maxillary palps bear the main olfactory receptors, while the gustatory receptors are in the labium, pharynx, feet, wing margins and female genitalia, enabling flies to taste their food by walking on it. The taste receptors in females at the tip of the abdomen receive information on the suitability of a site for ovipositing.
It provides birds with a large residual volume, allowing them to breathe much more slowly and deeply than a mammal of the same body mass. It provides a large source of air that is used not only for gaseous exchange, but also for the transfer of heat by evaporation.Inhalation begins at the mouth and the nostrils located at the front of the beak. The air then flows through the anatomical dead space of a highly vascular trachea (c.
Circulatory system of species subjected to orthostatic blood pressure (such as arboreal snakes) has evolved with physiological and morphological features to overcome the circulatory disturbance. For instance, in arboreal snakes the heart is closer to the head, in comparison with aquatic snakes. This facilitates blood perfusion to the brain.
|
What chemical element helps forms strong bones and teeth in humans?
|
[
"calcium",
"iron",
"potassium",
"magnesium"
] |
A
|
Minerals are chemical elements that are essential for body processes. They include calcium, which helps form strong bones and teeth, and potassium, which is needed for normal nerve and muscle function. Good sources of minerals include leafy, green vegetables, whole grains, milk, and meats.
Bone is a form of connective tissue found in the body, composed largely of hardened hydroxyapatite-containing collagen. In larger mammals, it is arranged in osteon regions. Bone matrix allows mineral salts such as calcium to be stored and provides protection for internal organs and support for locomotion.
A bone seeker is an element, often a radioisotope, that tends to accumulate in the bones of humans and other animals when it is introduced into the body. An example is strontium-90, which behaves chemically like calcium and can replace the calcium in bones. Other bone seekers include radium, and plutonium. An important thing to keep in mind is that - much like for toxic heavy metals the chemical state of the element may complicate such classifications.
Recent advances have been made in ceramics which include bioceramics such as dental implants and synthetic bones. Hydroxyapatite, the major mineral component of bone, has been made synthetically from several biological and chemical components and can be formed into ceramic materials. Orthopedic implants coated with these materials bond readily to bone and other tissues in the body without rejection or inflammatory reaction.
The human skeletal system is a complex organ in constant equilibrium with the rest of the body. In addition to support and structure of the body, bone is the major reservoir for many minerals and compounds essential for maintaining a healthy pH balance. The deterioration of the body with age renders the elderly particularly susceptible to and affected by poor bone health. Illnesses like osteoporosis, characterized by weakening of the bone's structural matrix, increases the risk of hip-fractures and other life-changing secondary symptoms.
Teeth (singular tooth) are small whitish structures found in the jaws (or mouths) of many vertebrates that are used to tear, scrape, milk and chew food. Teeth are not made of bone, but rather of tissues of varying density and hardness, such as enamel, dentine and cementum. Human teeth have a blood and nerve supply which enables proprioception. This is the ability of sensation when chewing, for example if we were to bite into something too hard for our teeth, such as a chipped plate mixed in food, our teeth send a message to our brain and we realise that it cannot be chewed, so we stop trying.
|
The limit to how much solute will dissolve in a given amount of solvent is called what?
|
[
"density",
"potency",
"strength",
"solubility"
] |
D
|
Solubility There is usually a limit to how much solute will dissolve in a given amount of solvent. This limit is called the solubility of the solute. Some solutes have a very small solubility, while other solutes are soluble in all proportions. Table 9.2 "Solubilities of Various Solutes in Water at 25°C (Except as Noted)" lists the solubilities of various solutes in water. Solubilities vary with temperature, so Table 9.2 "Solubilities of Various Solutes in Water at 25°C (Except as Noted)" includes the temperature at which the solubility was determined. Table 9.2 Solubilities of Various Solutes in Water at 25°C (Except as Noted).
Usually, the substance present in the greatest amount is considered the solvent. Solvents can be gases, liquids, or solids. One or more components present in the solution other than the solvent are called solutes. The solution has the same physical state as the solvent.
As the solvent composition changes due to an increase in the solvent that has gas diffused into the solution, the compound becomes increasingly insoluble in the solution and crystallizes.Interface/slow mixing (often performed in an NMR tube). Similar to the above, but instead of one solvent gas-diffusing into another, the two solvents mix (diffuse) by liquid-liquid diffusion. Typically a second solvent is "layered" carefully on top of the solution containing the compound.
A variation of the static method is to add a solution of the substance in a non-aqueous solvent, such as dimethyl sulfoxide, to an aqueous buffer mixture. Immediate precipitation may occur giving a cloudy mixture. The solubility measured for such a mixture is known as "kinetic solubility".
A solvent is a substance that is liquid at the temperature at which it is used. It has the ability to dissolve, dilute or extract other substances without changing them chemically and without changing itself. The traditional organic solvents (acetone, NMP, toluene, etc.), although very effective, raise today many problems as they are associated with adverse effects, both on the health and safety of workers (burns, cancer, eczema, brain disorder (encephalopathy), fetotoxicity (via the placenta), and inflammations of several peripheral nerves at the same time, as well as on the environment and health of the general population (smog precursors, water, air and ozone layer pollution). Solvents represent a major part of the chemical use in various domains (paints, coating, synthesis, ...) and in consequence define a lot of the environmental performance of the chemical industry.
A solute in dilute solution usually follows Henry's law rather than Raoult's law, and it is more usual to express the composition of the solution in terms of the molar concentration c (in mol/L) or the molality b (in mol/kg) of the solute rather than in mole fractions. The standard state of a dilute solution is a hypothetical solution of concentration co = 1 mol/L (or molality bo = 1 mol/kg) which shows ideal behaviour (also referred to as "infinite-dilution" behaviour). The standard state, and hence the activity, depends on which measure of composition is used. Molalities are often preferred as the volumes of non-ideal mixtures are not strictly additive and are also temperature-dependent: molalities do not depend on volume, whereas molar concentrations do.The activity of the solute is given by: a c , i = γ c , i c i c ⊖ a b , i = γ b , i b i b ⊖ {\displaystyle {\begin{aligned}a_{c,i}&=\gamma _{c,i}\,{\frac {c_{i}}{c^{\ominus }}}\\a_{b,i}&=\gamma _{b,i}\,{\frac {b_{i}}{b^{\ominus }}}\end{aligned}}}
|
What occurs when hot magma transforms rock that it contacts?
|
[
"existence metamorphism",
"form metamorphism",
"contact metamorphism",
"changing metamorphism"
] |
C
|
Contact metamorphism occurs when hot magma transforms rock that it contacts.
The melt uses local features like dikes and faults to migrate towards the surface.From numerical models, it is found that formation of magma which can migrate towards the upper crust occurs at a depth of about 30 km. It takes between 10,000 years and 1 million years to form the magma, depending on the emplacement rate of the mantle material. The emplacement rates in volcanic arc settings can vary between 2 and 20 mm/year.
Magma mixing is another aspect of granite formation that must be taken into account when observing granites. Magma mixing occurs when magmas of a different composition intrude a larger magma body. In some cases, the melts are immiscible and stay separated to form pillow like collections of denser mafic magmas on the bottom of less dense felsic magma chambers. The mafic pillow basalts will demonstrate a felsic matrix, suggesting magma mingling. Alternatively, the melts mix together and form a magma of a composition intermediate to the intrusive and intruded melt.
Consequently, the closing of the fractures in the roof rocks by precipitation of minerals allow confining pressure to increase once again. As time passed, increasingly felsic magmas rise up into the core of the volcano. Some of these later magmas probably erupt on the surface, forming new layers of volcanic rocks that will later be removed by erosion.Finally, volcanic activity ceased and erosion removed the upper portions of the volcano and exposed the intrusive rocks and stockwork mineralization that used to lie within.
Magma from the mantle or lower crust rises through the crust towards the surface. If magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. Viscous (thick) magma produces volcanoes characterised by explosive eruptions, while non-viscous (runny) magma produce volcanoes characterised by effusive eruptions pouring large amounts of lava onto the surface. In some cases, rising magma can cool and solidify without reaching the surface.
As the relatively cool subducting slab sinks deeper into the mantle, it is heated, causing hydrous minerals to break down. This releases water into the hotter asthenosphere, which leads to partial melting of the asthenosphere and volcanism. Both dehydration and partial melting occur along the 1,000 °C (1,830 °F) isotherm, generally at depths of 65 to 130 km (40 to 81 mi).Some lithospheric plates consist of both continental and oceanic lithosphere.
|
What term refers to entities, events or powers regarded as being beyond nature, and cannot be explained by scientific means?
|
[
"hypothetical",
"fictional",
"supernatural",
"natural"
] |
C
|
Science is based on the analysis of observations made either through our senses or by using special equipment. Science therefore cannot explain anything about the natural world that is beyond what is observable. The term supernatural refers to entities, events, or powers regarded as being beyond nature, in that such things cannot be explained by scientific means. They are not measurable or observable in the same way the natural world is, and are therefore considered to be outside the realm of scientific examination.
They do not support the introduction of any ultimate knower from a different or superior realm to account for what is known. Similarly, they do not tolerate "entities" or "realities" of any kind intruding as if from behind or beyond the knowing-known events, with power to interfere. They exclude the introduction of "faculties" or other "operators" of an organism's behaviors, and require for all investigations the direct observation and contemporaneous report of findings and results.
The philosophy of nature organizes the contingent material of the natural sciences systematically. As part of the philosophy of the real, in no way does it presume to "tell nature what it must be like." Historically, various interpreters have questioned Hegel's understanding of the natural sciences of his time. However, this claim has been largely refuted by recent scholarship.One of the very few ways in which the philosophy of nature might correct claims made by the natural sciences themselves is to combat reductive explanations; that is to discredit accounts employing categories not adequate to the complexity of the phenomena they purport to explain, as for instance, attempting to explain life in strictly chemical terms.Although Hegel and other Naturphilosophen aim to revive a teleological understanding of nature, they argue that their strictly internal or immanent concept of teleology is "limited to the ends observable within nature itself."
Matters are complicated by the fact that the words nature and natural have more than one meaning. On the one hand there is the main dictionary meaning for nature: "The phenomena of the physical world collectively, including plants, animals, the landscape, and other features and products of the earth, as opposed to humans or human creations." On the other hand, there is the growing awareness, especially since Charles Darwin, of humanities biological affinity with nature.The dualism of the first definition has its roots is an "ancient concept", because early people viewed "nature, or the nonhuman world as a divine Other, godlike in its separation from humans." In the West, Christianity's myth of the fall, that is the expulsion of humankind from the Garden of Eden, where all creation lived in harmony, into an imperfect world, has been the major influence.
Hence, naturalism is polemically defined as repudiating the view that there exists or could exist any entities which lie, in principle, beyond the scope of scientific explanation.Regarding the vagueness of the general term "naturalism", David Papineau traces the current usage to philosophers in early 20th century America such as John Dewey, Ernest Nagel, Sidney Hook, and Roy Wood Sellars: "So understood, 'naturalism' is not a particularly informative term as applied to contemporary philosophers. The great majority of contemporary philosophers would happily accept naturalism as just characterized—that is, they would both reject 'supernatural' entities, and allow that science is a possible route (if not necessarily the only one) to important truths about the 'human spirit'." Papineau remarks that philosophers widely regard naturalism as a "positive" term, and "few active philosophers nowadays are happy to announce themselves as 'non-naturalists'", while noting that "philosophers concerned with religion tend to be less enthusiastic about 'naturalism'" and that despite an "inevitable" divergence due to its popularity, if more narrowly construed, (to the chagrin of John McDowell, David Chalmers and Jennifer Hornsby, for example), those not so disqualified remain nonetheless content "to set the bar for 'naturalism' higher.
The concept is shared by many religious traditions, is found in a number of independently derived conceptualizations, and each of these has culturally distinct terminology. Some of the various relevant concepts and terms are: Immanence – usually applied in monotheistic, pantheistic, pandeistic, or panentheistic faiths to suggest that the spiritual world permeates the mundane. It is often contrasted with transcendence, in which the divine is seen to be outside the material world. Inner light – in various religions, the presence of God as a "light".
|
What causes an elastic force in springs?
|
[
"velocity",
"momentum",
"freezing",
"stretching or compressing"
] |
D
|
Springs like the ones in Figure below also have elastic force when they are stretched or compressed. And like stretchy materials, they return to their original shape when the stretching or compressing force is released. Because of these properties, springs are used in scales to measure weight. They also cushion the ride in a car and provide springy support beneath a mattress. Can you think of other uses of springs?.
Elastic mechanisms in animals are very important in the movement of vertebrate animals. The muscles that control vertebrate locomotion are affiliated with tissues that are springy, such as tendons, which lie within the muscles and connective tissue. A spring can be a mechanism for different actions involved in hopping, running, walking, and serve in other diverse functions such as metabolic energy conservation, attenuation of muscle power production, and amplification of muscle power production.When a body is running, walking or hopping, it uses springs as a way to store energy which indicates that elastic mechanisms have a great influence on its dynamics. When a force is applied to a spring it bends and stores energy in the form of elastic strain energy and when it recoils after the force has been released, this energy is released as well.
One may regard the entropic forces in polymer chains as arising from the thermal collisions that their constituent atoms experience with the surrounding material. It is this constant jostling that produces a resisting (elastic) force in the chains as they are forced to become straight. While stretching a rubber sample is the most common example of elasticity, it also occurs when rubber is compressed.
The deformation of the element induces stress to the element, which is the force applied to the element. This relation calculates the amount of stress experienced by the element due to the strain. One of the examples of this relation is Hooke's law.
A spring may be used in conjunction with the engine to swing the bow or stern away from a quayside to enable safe departure. springs Big tides caused by the alignment of the Moon and Sun. sprit A spar that supports a spritsail.
Strain energy density in a material is proportional to the product of its Young's modulus and the square of the applied strain. When multi-walled nanotubes (MWCNTs) are loaded, the majority of the applied load is borne by the outer shell. Owing to this limited load transfer between the different layers of MWCNTs, single walled nanotubes (SWCNTs) are more useful structural materials for springs.
|
What effect is responsible for flight paths looking curved?
|
[
"resonant effect",
"volumetric effect",
"tonal effect",
"coriolis effect"
] |
D
|
Zappy's. Flight paths look curved due to the Coriolis effect . CC BY-NC 3.0.
For these reasons, curved lines, typically circular arcs, are preferred as more aesthetically pleasing. They also have the ability to be adjusted to avoid intervening lines and points. Early automated line generation algorithms were typically straight lines, but recent algorithms have been successful at creating curved lines.
So, the same forces that change as sideslip changes (primarily sideforce, but also lift and drag) produce a larger moment about the CG of the aircraft. This is sometimes referred to as the pendulum effect.An extreme example of the effect of vertical CG on dihedral effect is a paraglider. The dihedral effect created by the very low vertical CG more than compensates for the negative dihedral effect created by the strong anhedral of the necessarily strongly downward curving wing.
The viewer's apparent looking directions are parallel to the curve's "hypcos" axis. Items directly beneath the radar appear as if optically viewed horizontally (i.e., from the side) and those at far ranges as if optically viewed from directly above. These curvatures are not evident unless large extents of near-range terrain, including steep slant ranges, are being viewed.
As the wheelset rolls on, the curvature decreases until the wheels reach the point where their effective diameters are equal and the path is no longer curving. But the trajectory has a slope at this point (it is a straight line which crosses diagonally over the centerline of the track) so that it overshoots the centerline of the track and the effective diameters reverse (the formerly smaller diameter wheel becomes the larger diameter and conversely).
Optical illusions such as the Fraser spiral strikingly demonstrate limitations in human visual perception, creating what the art historian Ernst Gombrich called a "baffling trick." The black and white ropes that appear to form spirals are in fact concentric circles. The mid-twentieth century Op art or optical art style of painting and graphics exploited such effects to create the impression of movement and flashing or vibrating patterns seen in the work of artists such as Bridget Riley, Spyros Horemis, and Victor Vasarely.
|
Wetlands are environments in which the soil is either permanently or periodically saturated with what?
|
[
"hydrogen",
"oil",
"water",
"spores"
] |
C
|
Wetlands Wetlands are environments in which the soil is either permanently or periodically saturated with water. Wetlands are different from lakes and ponds because wetlands exhibit a near continuous cover of emergent vegetation. Emergent vegetation consists of wetland plants that are rooted in the soil but have portions of leaves, stems, and flowers extending above the water’s surface. There are several types of wetlands including marshes, swamps, bogs, mudflats, and salt marshes (Figure 20.33).
For example, seasonal flooding and drying may occur with yearly changes in precipitation, causing seasonal changes in the wetland community that maintain it at a stable state. However, unusually heavy rain or unusually severe drought may cause the wetland to enter a positive feedback loop where it begins to change in a linear direction. Since wetlands are sensitive to changes in the natural processes that maintain them, human activities, invasive species, and climate change could initiate long-term changes in wetland ecosystems.
The specific ecological effects and their magnitudes vary depending on the concentrations, frequency, and chemical makeup of runoff pollutants. Furthermore, marshes may be drained, dredged, and filled to make the land available for coastal development and agriculture. Marshes are also commonly ditched and drained for mosquito and other pest control.
The salt marsh's resilience depends upon its increase in bed level rate being greater than that of sea levels increasing rate, otherwise the marsh will be overtaken and drowned. Biomass accumulation can be measured in the form of above-ground organic biomass accumulation, and below-ground inorganic accumulation by means of sediment trapping and sediment settling from suspension.
Contaminant remediation in aquifers. The decision problem is where to locate wells, and choose a pumping rate, to minimize the cost to prevent spread of a contaminant. The constraints are associated with the hydrogeological flows.Water allocation to improve wetlands. This optimization model recommends water allocation and invasive vegetation control to improve wetland habitat of priority bird species.
Physical, chemical, and biological processes combine in wetlands to remove contaminants from wastewater. An understanding of these processes is fundamental not only to designing wetland systems but to understanding the fate of chemicals once they enter the wetland. Theoretically, wastewater treatment within a constructed wetland occurs as it passes through the wetland medium and the plant rhizosphere. A thin film around each root hair is aerobic due to the leakage of oxygen from the rhizomes, roots, and rootlets.
|
When the ground absorbs the water and it settles below the surface it is called what?
|
[
"wastewater",
"glacier",
"precipitation",
"groundwater"
] |
D
|
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.
In an arid region, rainwater sinks into the ground very quickly. Later, as the surface dries out, the water below the surface rises, carrying up dissolved minerals from lower layers. These precipitate as water evaporates and carbon dioxide is lost.
Pendular water is the moisture clinging to particles, such as soil particles or sand, because of surface tension.At the moisture content of a specific yield, gravity drainage will cease. This term relates to hydrology and groundwater flow.
It receives infiltration from the surface layer and loses water through ET and by percolation into the storage layer below it. The storage layer consists of coarse crushed stone or gravel. It receives percolation from the soil zone above it and loses water by either infiltration into the underlying natural soil or by outflow through a perforated pipe underdrain system.
Recharge may also occur by saturated flow when water bypasses the soil matrix as it moves to depth in macropores (e.g. root holes, fractures). Excessive recharge may raise the water table locally, or at a landscape scale. When brackish to saline groundwater intersects the ground surface and discharges, this is termed saline discharge. Areas of discharge are called saline seeps (when groundwater intersects the soil surface) or saline scalds (where water is lost by evaporation only). Groundwater discharge manifests in such problems as: reduced agricultural production, degradation of natural environment, reduced surface water quality, damage to infrastructure including roads, as well as soil erosion and denudation of land.
|
Some metabolic pathways release what by breaking down complex molecules to simpler compounds?
|
[
"fat",
"hydrogen",
"water",
"energy"
] |
D
|
An alternative route for glucose breakdown is the pentose phosphate pathway, which reduces the coenzyme NADPH and produces pentose sugars such as ribose, the sugar component of nucleic acids.Fats are catabolized by hydrolysis to free fatty acids and glycerol. The glycerol enters glycolysis and the fatty acids are broken down by beta oxidation to release acetyl-CoA, which then is fed into the citric acid cycle. Fatty acids release more energy upon oxidation than carbohydrates.
The pyruvate dehydrogenase complex is responsible for the oxidative decarboxylation of pyruvate, with the final product being Acetyl CoA. Overall the complex catalyzes five reactions, with the overall reaction being: Pyruvate + CoA + NAD+ → acetyl-CoA + CO2There are three different coenzymes required throughout the 5 steps that this complex carries out: thiamine pyrophosphate (TPP), lipoamide, and coenzyme A. This step is only one of the central metabolic pathway carried out by eukaryotes, in which glucose is oxidized to form carbon dioxide, water, and ATP. The E1 complex specifically uses the TPP cofactor to cleave the Calpha-C(=O) bond of pyruvate, and then transfer the acetyl group to the TPP coenzyme, thus resulting in an intermediate, hydroxylethyl-Tpp*E1, and producing CO2. The thiazolium ring on the TPP is ideal for adding to carbonyl groups and acting as an electron sink, or a group that can pull electrons from a reaction and stabilize an electron-deficient intermediate.
Within the metabolic network, the small molecules take the roles of nodes, and they could be either carbohydrates, lipids, or amino acids. The reactions which convert these small molecules from one form to another are represented as edges. It is possible to use network analyses to infer how selection acts on metabolic pathways.
Cofactor engineering is significant in the manipulation of metabolic pathways. A metabolic pathway is a series of chemical reactions that occur in an organism. Metabolic engineering is the subject of altering the fluxes within a metabolic pathway. In metabolic engineering, a metabolic pathway can be directly altered by changing the functionality of the enzymes involved in the pathway.
There are many variations on this theme, as different organisms are able to degrade different polymers and secrete different waste products. Some organisms are even able to degrade more recalcitrant compounds such as petroleum compounds or pesticides, making them useful in bioremediation. Biochemically, prokaryotic heterotrophic metabolism is much more versatile than that of eukaryotic organisms, although many prokaryotes share the most basic metabolic models with eukaryotes, e. g. using glycolysis (also called EMP pathway) for sugar metabolism and the citric acid cycle to degrade acetate, producing energy in the form of ATP and reducing power in the form of NADH or quinols.
|
What is the smallest portion of a crystal lattice?
|
[
"ionic cell",
"function cell",
"unit cell",
"element cell"
] |
C
|
A unit cell is the smallest portion of a crystal lattice that shows the three-dimensional pattern of the entire crystal. A crystal can be thought of as the same unit cell repeated over and over in three dimensions. The Figure below illustrates the relationship of a unit cell to the entire crystal lattice.
There are 24 even unimodular lattices of dimension 24, called the Niemeier lattices. The mass formula for them is checked in (Conway & Sloane 1998, pp. 410–413).
Simple cubic lattices can be distorted into lower symmetries, represented by lower crystal systems:
The strictest form of order in a solid is lattice periodicity: a certain pattern (the arrangement of atoms in a unit cell) is repeated again and again to form a translationally invariant tiling of space. This is the defining property of a crystal. Possible symmetries have been classified in 14 Bravais lattices and 230 space groups.
Lattices are structures formed of arrays of uniformly sized cells. Ceramic lattice nanostructures have been formed using hollow tubes of titanium nitride (TiN). Using vertex-connected, tessellated octahedra with 7-nm hollow struts with elliptical cross-sections and wall thickness of 75-nm produced approximately cubic cells 100-nm on a side at a scale of up to 1 cubic millimeter.
The energy associated with the elastic bending of the lattice can be reduced by inserting a dislocation, which is essentially a half-plane of atoms that act like a wedge, that creates a permanent misorientation between the two sides. As the grain is bent further, more and more dislocations must be introduced to accommodate the deformation resulting in a growing wall of dislocations – a low-angle boundary. The grain can now be considered to have split into two sub-grains of related crystallography but notably different orientations.
|
What is one major cause of skin cancer?
|
[
"visible light",
"sunscreen",
"ultraviolet light",
"infrared light"
] |
C
|
The most important way to keep your skin healthy is to protect it from ultraviolet light. Over-exposure to ultraviolet light can cause skin cancer. Keeping the skin clean can help prevent acne.
There are three main types of skin cancer: basal-cell skin cancer (basal-cell carcinoma) (BCC), squamous-cell skin cancer (squamous-cell carcinoma) (SCC) and malignant melanoma. Basal-cell carcinomas are most commonly present on sun-exposed areas of the skin, especially the face. They rarely metastasize and rarely cause death.
Exposure to ultraviolet radiation (UVR), whether from the sun or tanning devices is known to be a major cause of the three main types of skin cancer: non-melanoma skin cancer (basal cell carcinoma and squamous cell carcinoma) and melanoma. Overexposure to UVR induces at least two types of DNA damage: cyclobutane–pyrimidine dimers (CPDs) and 6–4 photoproducts (6–4PPs). While DNA repair enzymes can fix some mutations, if they are not sufficiently effective, a cell will acquire genetic mutations which may cause the cell to die or become cancerous.
Skin cancers result in 80,000 deaths a year as of 2010, 49,000 of which are due to melanoma and 31,000 of which are due to non-melanoma skin cancers. This is up from 51,000 in 1990.More than 3.5 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. One in five Americans will develop skin cancer at some point of their lives. The most common form of skin cancer is basal-cell carcinoma, followed by squamous cell carcinoma. Unlike for other cancers, there exists no basal and squamous cell skin cancers registry in the United States.
Radiation exposure such as ultraviolet radiation and radioactive material is a risk factor for cancer. Many non-melanoma skin cancers are due to ultraviolet radiation, mostly from sunlight. Sources of ionizing radiation include medical imaging and radon gas.Ionizing radiation is not a particularly strong mutagen.
In a few cases, only one cause exists: for example, the virus HHV-8 causes all Kaposi's sarcomas. However, with the help of cancer epidemiology techniques and information, it is possible to produce an estimate of a likely cause in many more situations. For example, lung cancer has several causes, including tobacco use and radon gas.
|
Which important decomposers are known to live just about anywhere on earth?
|
[
"protazoas",
"archeans",
"viruses",
"sporozoans"
] |
B
|
Archaeans are now known to live just about everywhere on Earth. They are important decomposers. Many live in close relationships with other organisms. They are generally harmless and often beneficial.
File:Cogumelos brancos.jpg This high rate of decomposition is the result of phosphorus levels in the soils, precipitation, high temperatures and the extensive microorganism communities. In addition to the bacteria and other microorganisms, there are an abundance of other decomposers such as fungi and termites that aid in the process as well. Nutrient recycling is important because below ground resource availability controls the above ground biomass and community structure of tropical rainforests. These soils are typically phosphorus limited, which inhibits net primary productivity or the uptake of carbon.
Studies have shown that each stage is characterized by particular insect species, the succession of which depends on chemical and physical properties of remains, rate of decomposition and environmental factors. Insects associated with decomposing remains may be useful in determining post-mortem interval, manner of death, and the association of suspects. Insect species and their times of colonization will vary according to the geographic region, and therefore may help determine if remains have been moved.
Decomposition rates vary among ecosystems. The rate of decomposition is governed by three sets of factors—the physical environment (temperature, moisture, and soil properties), the quantity and quality of the dead material available to decomposers, and the nature of the microbial community itself. : 194 Temperature controls the rate of microbial respiration; the higher the temperature, the faster the microbial decomposition occurs. Temperature also affects soil moisture, which affects decomposition.
Through this process of eating the detritus many times over and harvesting the microorganisms from it, the detritus thins out, becomes fractured and becomes easier for the microorganisms to use, and so the complex carbohydrates are also steadily broken down and disappear over time. What is left behind by the detritivores is then further broken down and recycled by decomposers, such as bacteria and fungi. This detritus cycle plays a large part in the so-called purification process, whereby organic materials carried in by rivers is broken down and disappears, and an extremely important part in the breeding and growth of marine resources. In ecosystems on land, far more essential material is broken down as dead material passing through the detritus chain than is broken down by being eaten by animals in a living state. In both land and aquatic ecosystems, the role played by detritus is too large to ignore.
In food webs, saprophages generally play the roles of decomposers. There are two main branches of saprophages, broken down by nutrient source. There are necrophages which consume dead animal biomass, and thanatophages which consume dead plant biomass.
|
In the scientific method, what is the initial, unproven explanation for why something is occurring?
|
[
"concepts",
"idea",
"theories",
"hypothesis"
] |
D
|
The scientific method is not a step by step, linear process. It is a way of learning about the world through the application of knowledge. Scientists must be able to have an idea of what the answer to an investigation should be. In order for scientists to make educated guesses about the answers, they will base their guesses on previous knowledge, with the notion of extending that knowledge. Scientists will often make an observation and then form a hypothesis to explain why a phenomenon occurred. They use all of their knowledge and a bit of imagination in their journey of discovery.
The scientific method is iterative. At any stage, it is possible to refine its accuracy and precision, so that some consideration will lead the scientist to repeat an earlier part of the process. Failure to develop an interesting hypothesis may lead a scientist to re-define the subject under consideration. Failure of a hypothesis to produce interesting and testable predictions may lead to reconsideration of the hypothesis or of the definition of the subject.
Scientists prefer explanations that are consistent with known and supported facts and evidence and require the fewest assumptions to fill the remaining gaps. Many of the alternative claims made in creation science retreat from simpler scientific explanations and introduce more complications and conjecture into the equation. Creation science is not, and cannot be, empirically or experimentally tested: Creationism posits supernatural causes which lie outside the realm of methodological naturalism and scientific experiment.
In a 1965 paper, Gilbert Harman explained that enumerative induction is not an autonomous phenomenon, but is simply a disguised consequence of Inference to the Best Explanation (IBE). IBE is otherwise synonymous with C S Peirce's abduction. Many philosophers of science espousing scientific realism have maintained that IBE is the way that scientists develop approximately true scientific theories about nature.
Human observations are biased toward confirming the observer's conscious and unconscious expectations and view of the world; we "see what we expect to see". In psychology, this is called confirmation bias. Since the object of scientific research is the discovery of new phenomena, this bias can and has caused new discoveries to be overlooked; one example is the discovery of x-rays. It can also result in erroneous scientific support for widely held cultural myths, on the other hand, as in the scientific racism that supported ideas of racial superiority in the early 20th century. Correct scientific technique emphasizes careful recording of observations, separating experimental observations from the conclusions drawn from them, and techniques such as blind or double blind experiments, to minimize observational bias.
It plays an equally central role in the sciences, which often start with many particular observations and then apply the process of generalization to arrive at a universal law.A well-known issue in the field of inductive reasoning is the so-called problem of induction. It concerns the question of whether or why anyone is justified in believing the conclusions of inductive inferences. This problem was initially raised by David Hume, who holds that future events need not resemble past observations. In this regard, inductive reasoning about future events seems to rest on the assumption that nature remains uniform.
|
What is the name of an element with a different number of neutrons?
|
[
"isotope",
"mineral",
"reaction",
"solution"
] |
A
|
All atoms of the same element have the same number of protons, but some may have different numbers of neutrons. For example, all carbon atoms have six protons, and most have six neutrons as well. But some carbon atoms have seven or eight neutrons instead of the usual six. Atoms of the same element that differ in their numbers of neutrons are called isotopes . Many isotopes occur naturally. Usually one or two isotopes of an element are the most stable and common. Different isotopes of an element generally have the same physical and chemical properties. That’s because they have the same numbers of protons and electrons. For a video explanation of isotopes, go to this URL:.
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.
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.
Light elements such as helium-4 have close to a 1:1 neutron:proton ratio. The heaviest elements such as lead have close to 1.5 neutrons per proton(e.g. 1.536 in lead-208). No nuclide heavier than lead-208 is stable; these heavier elements have to shed mass to achieve stability, mostly by alpha decay.
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.
Alpha process elements (or alpha elements) are so-called since their most abundant isotopes are integer multiples of four – the mass of the helium nucleus (the alpha particle). These isotopes are called alpha nuclides. The stable alpha elements are: C, O, Ne, Mg, Si, and S. The elements Ar and Ca are "observationally stable".
|
Nitrogen and sulfur oxides form what type of rain?
|
[
"common rain",
"toxic rain",
"heavy rain",
"acid rain"
] |
D
|
Both nitrogen and sulfur oxides are toxic to humans. These compounds can cause lung diseases or make them worse. Nitrogen and sulfur oxides form acid rain, which is described in the next concept.
Once sulfur dioxide and nitrogen oxide are introduced into the atmosphere, they can react with cloud droplets (cloud condensation nuclei), raindrops, or snowflakes, forming sulfuric acid and nitric acid. With the interaction between water droplets and sulfuric and nitric acids, wet deposition occurs and creates acid rain. As a result, these acids would be displaced into various environments and vegetation during precipitation, having significant aerial distance (hundreds of kilometres) from the emission source.
An important secondary pollutant for photochemical smog is ozone, which is formed when hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight; nitrogen dioxide (NO2), which is formed as nitric oxide (NO) combines with oxygen (O2) in the air. In addition, when SO2 and NOx are emitted they eventually are oxidized in the troposphere to nitric acid and sulfuric acid, which, when mixed with water, form the main components of acid rain. All of these harsh chemicals are usually highly reactive and oxidizing.
In moist air or moist argon, the metal oxidizes rapidly, producing a mixture of oxides and hydrides. If the metal is exposed long enough to a limited amount of water vapor, a powdery surface coating of PuO2 is formed. Also formed is plutonium hydride but an excess of water vapor forms only PuO2.Plutonium shows enormous, and reversible, reaction rates with pure hydrogen, forming plutonium hydride.
In wet deposition, atmospheric hydrometeors (rain drops, snow etc.) scavenge aerosol particles. This means that wet deposition is gravitational, Brownian and/or turbulent coagulation with water droplets. Different types of wet deposition include: Below-cloud scavenging. This happens when falling rain droplets or snow particles collide with aerosol particles through Brownian diffusion, interception, impaction and turbulent diffusion.
Nitrogen can be fixed by lightning converting nitrogen gas (N2) and oxygen gas (O2) in the atmosphere into NOx (nitrogen oxides). The N2 molecule is highly stable and nonreactive due to the triple bond between the nitrogen atoms. Lightning produces enough energy and heat to break this bond allowing nitrogen atoms to react with oxygen, forming NOx. These compounds cannot be used by plants, but as this molecule cools, it reacts with oxygen to form NO2, which in turn reacts with water to produce HNO2 (nitrous acid) or HNO3 (nitric acid). When these acids seep into the soil, they make NO3 (nitrate), which is of use to plants.
|
Polyester fabric's resistance to wrinkling comes from the cross-linking of what?
|
[
"algae strands",
"velocity strands",
"polymer strands",
"wool strands"
] |
C
|
PET is used in tires, photographic film, food packaging, and clothing. Polyester fabric is used in permanent-press clothing. Its resistance to wrinkling comes from the cross-linking of the polymer strands.
The range of materials available is much wider however, since all polymers become elastomeric above their Glass transition temperature. However, the elastomeric state is unstable because chains can slip past one another resulting in creep or stress relaxation under static or dynamic load conditions. Chemical cross links add the stability to the network that is needed for most practical applications.
The resulting modification of mechanical properties depends strongly on the cross-link density. Low cross-link densities increase the viscosities of polymer melts. Intermediate cross-link densities transform gummy polymers into materials that have elastomeric properties and potentially high strengths. Very high cross-link densities can cause materials to become very rigid or glassy, such as phenol-formaldehyde materials.
Linen-cotton blends are wrinkle resistant and retain heat more effectively than only linen, and are thinner, stronger and lighter than only cotton.In addition to the textile industry, cotton is used in fishing nets, coffee filters, tents, explosives manufacture (see nitrocellulose), cotton paper, and in bookbinding. Fire hoses were once made of cotton.
When discussing fabric properties for use on a structure, there are several terms that are commonly used: Tensile strength is a basic indicator of relative strength. It is fundamental for architectural fabrics that function primarily in tension. Tear Strength is important in that if a fabric ruptures in place, it generally will do so by tearing. This can occur when a local stress concentration or local damage results in the failure of one yarn, which thereby increases the stress on remaining yarns.
Traditionally, Inuit seamstresses used thread made from sinew, called ivalu. Modern seamstresses generally use thread made from cotton, linen, or synthetic fibres, which are easier to find and less difficult to work with, although these materials are less waterproof compared to ivalu.Tight, high-quality seams were essential to prevent cold air and moisture from entering the garment. Four main stitches were used: from most to least common, they were the overcast stitch, the tuck or gathering stitch, the running stitch, and the waterproof stitch or ilujjiniq.
|
What term refers to the sequence of community and ecosystem changes after a disturbance?
|
[
"ecological succession",
"progressions",
"disturbance succession",
"physiological succession"
] |
A
|
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.
: 43 Ecosystems can also be divided and degraded by infrastructure development outside of urban areas. : 46 Biodiversity loss can sometimes be reversed through ecological restoration or ecological resilience, such as through the restoration of abandoned agricultural areas;: 45 however, it may also be permanent (e.g. through land loss). The planet's ecosystem is quite sensitive: occasionally, minor changes from a healthy equilibrium can have dramatic influence on a food web or food chain, up to and including the coextinction of that entire food chain.
The scale of ecological dynamics can operate like a closed system, such as aphids migrating on a single tree, while at the same time remaining open with regard to broader scale influences, such as atmosphere or climate. Hence, ecologists classify ecosystems hierarchically by analyzing data collected from finer scale units, such as vegetation associations, climate, and soil types, and integrate this information to identify emergent patterns of uniform organization and processes that operate on local to regional, landscape, and chronological scales. To structure the study of ecology into a conceptually manageable framework, the biological world is organized into a nested hierarchy, ranging in scale from genes, to cells, to tissues, to organs, to organisms, to species, to populations, to communities, to ecosystems, to biomes, and up to the level of the biosphere. This framework forms a panarchy and exhibits non-linear behaviors; this means that "effect and cause are disproportionate, so that small changes to critical variables, such as the number of nitrogen fixers, can lead to disproportionate, perhaps irreversible, changes in the system properties. ": 14
The importance of stability in community ecology is clear. An unstable ecosystem will be more likely to lose species. Thus, if there is indeed a link between diversity and stability, it is likely that losses of diversity could feedback on themselves, causing even more losses of species.
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.
|
What is the network of fibers that organizes structures and activities in the cell called?
|
[
"cytoskeleton",
"enzymes",
"cytoplasm",
"DNA"
] |
A
|
6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell.
Many of the short association fibers (also called arcuate or "U"-fibers) lie immediately beneath the gray substance of the cortex of the hemispheres, and connect together adjacent gyri. Some pass from one wall of the sulcus to the other.
The walls of seminiferous tubules are lined with primitive germ layer cells and by Sertoli cells. The barrier is formed by tight junctions, adherens junctions and gap junctions between the Sertoli cells, which are sustentacular cells (supporting cells) of the seminiferous tubules, and divides the seminiferous tubule into a basal compartment (outer side of the tubule, in contact with blood and lymph) and an endoluminal compartment (inner side of the tubule, isolated from blood and lymph). The tight junctions are formed by intercellular adhesion molecules in between cells that are anchored to actin fibers within the cells. For the visualization of the actin fibers within the seminiferous tubules see Sharma et al.'s immunofluorescence studies.
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.
The mossy fiber and climbing fiber inputs each carry fiber-specific information; the cerebellum also receives dopaminergic, serotonergic, noradrenergic, and cholinergic inputs that presumably perform global modulation.The cerebellar cortex is divided into three layers. At the bottom lies the thick granular layer, densely packed with granule cells, along with interneurons, mainly Golgi cells but also including Lugaro cells and unipolar brush cells. In the middle lies the Purkinje layer, a narrow zone that contains the cell bodies of Purkinje cells and Bergmann glial cells.
The parabasal fiber provides a surface for microtubule formation, and there is one parabasal fiber for each flagellar band. The parabasal fiber possesses a dark lining that has been suggested to be a microtubule organizing centre for the axostyle. The size of parabasal fibers decreases as they extend further past the apex, to the point where they cannot be observed in the mid-region or base of the cell.
|
Decreasing the volume of a gas and keeping everything else the same will cause its pressure to change in what way?
|
[
"heat up",
"decrease",
"lower",
"increase"
] |
D
|
When gas molecules bump into things, it creates pressure. Pressure is greater when gas molecules occupy a smaller space, because greater crowding results in more collisions. This explains why decreasing the volume of a gas increases its pressure.
This law has the following important consequences: If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas. If the temperature and volume remain constant, then the pressure of the gas changes is directly proportional to the number of molecules of gas present. If the number of gas molecules and the temperature remain constant, then the pressure is inversely proportional to the volume. If the temperature changes and the number of gas molecules are kept constant, then either pressure or volume (or both) will change in direct proportion to the temperature.
Gas equations of state, which may be expressed in combination as the Combined gas law, or the Ideal gas law within the range of pressures normally encountered by divers, or as the traditionally expressed gas laws relating the relationships between two properties when the others are held constant, are used to calculate variations of pressure, volume and temperature, such as: Boyle's law, which describes the change in volume with a change in pressure at a constant temperature. For example, the volume of gas in a non-rigid container (such as a diver's lungs or buoyancy compensation device), decreases as external pressure increases while the diver descends in the water. Likewise, the volume of gas in such non-rigid containers increases on the ascent. Changes in the volume of gases in the diver and the diver's equipment affect buoyancy.
When operated within an atmosphere, pressurization of the typically very thin-walled propellant tanks must guarantee positive gauge pressure at all times to avoid catastrophic collapse of the tank. Liquid propellants are subject to slosh, which has frequently led to loss of control of the vehicle.
Endothermic transformations in the foam zone and fizz zone require energy initially provided by the primer and subsequently released in a luminous outer flame zone where the simpler gas molecules react to form conventional combustion products like steam and carbon monoxide.The heat transfer rate of smokeless propellants increases with pressure; so the rate of gas generation from a given grain surface area increases at higher pressures. Accelerating gas generation from fast burning propellants may rapidly create a destructively high pressure spike before bullet movement increases reaction volume. Conversely, propellants designed for a minimum heat transfer pressure may cease decomposition into gaseous reactants if bullet movement decreases pressure before a slow burning propellant has been consumed. Unburned propellant grains may remain in the barrel if the energy-releasing flame zone cannot be sustained in the resultant absence of gaseous reactants from the inner zones.
If the internal plunger has a diaphragm which extends to the side of the gas tube, it will cease to move once an applied force is constant and will support a weight, like a normal spring. If a fine hole exists in the plunger, however, it is termed a "slow-dampened spring" and can be used on heavy doors and windows. A gas spring designed for fast operation is termed a "quick gas spring" and is used in the manufacture of air guns and recoil buffers. Reducing the gas volume and hence increasing its internal pressure by means of a movable end stop, or allowing one tube to slide over another, can allow the characteristics of a gas spring to be adjusted during operation.
|
What evolutionary strategy enables substantial activity during sleep for some animals?
|
[
"hibernation",
"adaptation",
"reproduction",
"mutation"
] |
B
|
The brain requires sleep for restoration, whereas these processes can take place during quiescent waking in the rest of the body. The essential function of sleep may be its restorative effect on the brain: "Sleep is of the brain, by the brain and for the brain." This theory is strengthened by the fact that sleep is observed to be a necessary behavior across most of the animal kingdom, including some of the least evolved animals which have no need for other functions of sleep, such as memory consolidation or dreaming.
Animal studies showed that sleep deprivation can reduce the number of neurons in the locus coeruleus. Therefore the possibility of lasting damages to human brain functions due to sleep deprivation has become a matter of discussion.
The sleeping brain has been shown to remove metabolic waste products at a faster rate than during an awake state. While awake, metabolism generates reactive oxygen species, which are damaging to cells. In sleep, metabolic rates decrease and reactive oxygen species generation is reduced allowing restorative processes to take over.
Whether fish sleep or not is an open question, to the point of having inspired the title of several popular science books. In birds and mammals, sleep is defined by eye closure and the presence of typical patterns of electrical activity in the brain, including the neocortex, but fish lack eyelids and a neocortex. Some species that always live in shoals or that swim continuously (because of a need for ram ventilation of the gills, for example) are suspected never to sleep. There is also doubt about certain blind species that live in caves.However, other fish do seem to sleep, especially when purely behavioral criteria are used to define sleep. For example, zebrafish, tilapia, tench, brown bullhead, and swell shark become motionless and unresponsive at night (or by day, in the case of the swell shark); Spanish hogfish and blue-headed wrasse can even be lifted by hand all the way to the surface without evoking a response. On the other hand, sleep patterns are easily disrupted and may even disappear during periods of migration, spawning, and parental care.
Nocturnal animals are often energetically challenged due to being most active in the nighttime when ambient temperatures are lower than through the day, and so they lose a lot of energy in the form of body heat. According to the circadian thermos-energetics (CTE) hypothesis, animals that are expending more energy than they are taking in (through food and sleep) will be more active in the light cycle, meaning they will be more active in the day. This has been shown in studies done on small nocturnal mice in a laboratory setting.
|
The cells of the blastocyst form an inner cell mass called the what?
|
[
"embryoblast",
"blastocyst",
"chloroplast",
"xerophyte"
] |
A
|
The cells of the blastocyst form an inner cell mass and an outer cell layer, as shown in Figure below . The inner cell mass is called the embryoblast. These cells will soon develop into an embryo. The outer cell layer is called the trophoblast. These cells will develop into other structures needed to support and nourish the embryo.
In mammals, roughly 50–150 cells make up the inner cell mass during the blastocyst stage of embryonic development, around days 5–14. These have stem-cell capability. In vivo, they eventually differentiate into all of the body's cell types (making them pluripotent).
Once the blastocyst is formed, it undergoes implantation into the endometrium. During implantation the blastocyst, which contains the inner cell mass, undergoes cellular differentiation into the two layers of the bilaminar embryonic disc. One of which is the epiblast, also known as the primitive ectoderm.
This polarisation leaves a cavity, the blastocoel, creating a structure that is now termed the blastocyst. (In animals other than mammals, this is called the blastula). The trophoblasts secrete fluid into the blastocoel.
In biology, a blastomere is a type of cell produced by cell division (cleavage) of the zygote after fertilization; blastomeres are an essential part of blastula formation, and blastocyst formation in mammals.
A blastema (Greek βλάστημα, "offspring") is a mass of cells capable of growth and regeneration into organs or body parts. The changing definition of the word "blastema" has been reviewed by Holland (2021). A broad survey of how blastema has been used over time brings to light a somewhat involved history. The word entered the biomedical vocabulary in 1799 to designate a sinister acellular slime that was the starting point for the growth of cancers, themselves, at the time, thought to be acellular, as reviewed by Hajdu (2011, Cancer 118: 1155-1168).
|
How do all musical instruments create sound?
|
[
"vibration",
"condensation",
"stimulation",
"conduction"
] |
A
|
All musical instruments create sound by causing matter to vibrate. The vibrations start sound waves moving through the air.
This allows the instrument to be played totally acoustically, with no electronic sounds, or operated to just use the electronics, or used with a mix of acoustic and digital sounds. There are a myriad of sound combinations of acoustic and electronic sounds, which require a trained ear to play properly mixed sounds. These hybrids also require an amplifier and sound module, of which some models have said module mounted inside the acoustic instrument along with the reeds. (See Terminology below)
The compositional practice of acousmatic music features acousmatic sound, sound which is heard but not seen, as a central musical aspect. Other aspects traditionally thought of as 'musical' such as melody, harmony, rhythm, metre may be present but more often consideration is given to sound-based characteristics such as timbre and spectrum. Compositional materials can include sounds derived from musical instruments, voice, electronically generated sound, or sounds employing audio signal processing, as well as general sound effects and field recordings.
A number of musical instruments, other than the pipe organ, are based on the edge-tone phenomenon, the most common of which are the flute, the piccolo (a small version of the flute), and the recorder. The flute can be blown lateral to the instrument or at the end, as the other ones are. A native end-blown flute is shown in the figure.
For instance, a player might press on the seventh fret on a guitar and pluck it at the head side to make a tone resonate at the opposing side. On electric instruments, this technique generates multitone sounds reminiscent of a clock or bell. Electric string instruments, such as the electric guitar, can also be played without touching the strings by using audio feedback.
The capacity to generate music through autonomous, non-programmable means has long been sought after since the days of Antiquity, and with developments in artificial intelligence, two particular domains have arisen: The robotic creation of music, whether through machines playing instruments or sorting of virtual instrument notes (such as through MIDI files) Directly generating waveforms that perfectly recreate instrumentation and human voice without the need for instruments, MIDI, or organizing premade notes.
|
What system disorders include kidney stones, kidney failure, and urinary tract infections?
|
[
"nervous system",
"digestive system",
"renal system",
"urinary system"
] |
D
|
Disorders of the urinary system include kidney stones, kidney failure, and urinary tract infections.
Clinical features may include constitutional symptoms like fever, arthralgia, myalgia, loss of appetite, weight loss and fatigue. A variety of organs can be affected, which causes a wide range of symtoms such as cough, shortness of breath, hemoptysis (coughing up of blood), symtoms of kidney failure, skin manifestations (palpable purpura and livedo racemosa), seizures or peripheral neuropathy, abdominal pain The kidneys are affected in up to 80% of cases with signs of blood and protein in the urine and the injury can lead to either rapidly or slowly progressive kidney failure. The lungs are affected in 20-50% of cases with findings of pulmonary hemorrhage, or chronic pulmonary fibrosis leading to respiratory failure.
Urolithiasis refers to stones originating anywhere in the urinary system, including the kidneys and bladder. Nephrolithiasis refers to the presence of such stones in the kidneys. Calyceal calculi are aggregations in either the minor or major calyx, parts of the kidney that pass urine into the ureter (the tube connecting the kidneys to the urinary bladder). The condition is called ureterolithiasis when a calculus is located in the ureter. Stones may also form or pass into the bladder, a condition referred to as bladder stones.
The signs and symptoms of primary hyperparathyroidism are those of hypercalcemia. They are classically summarized by "stones, bones, abdominal groans, thrones and psychiatric overtones". "Stones" refers to kidney stones, nephrocalcinosis, and diabetes insipidus (polyuria and polydipsia). These can ultimately lead to kidney failure.
Whatever system a specific condition may seem restricted to, all the other systems are usually reviewed in a comprehensive history. The review of systems often includes all the main systems in the body that may provide an opportunity to mention symptoms or concerns that the individual may have failed to mention in the history. Health care professionals may structure the review of systems as follows: Cardiovascular system (chest pain, dyspnea, ankle swelling, palpitations) are the most important symptoms and you can ask for a brief description for each of the positive symptoms. Respiratory system (cough, haemoptysis, epistaxis, wheezing, pain localized to the chest that might increase with inspiration or expiration).
Renal colic is a type of abdominal pain commonly caused by obstruction of ureter from dislodged kidney stones. The most frequent site of obstruction is the vesico-ureteric junction (VUJ), the narrowest point of the upper urinary tract. Acute obstruction and the resultant urinary stasis (disruption of urine flow) can distend the ureter (hydroureter) and cause a reflexive peristaltic smooth muscle spasm, which leads to a very intense visceral pain transmitted via the ureteric plexus.
|
What type of respiration has the advantage of releasing more energy?
|
[
"kinetic",
"anaerobic",
"elastic",
"aerobic"
] |
D
|
A major advantage of aerobic respiration is the amount of energy it releases. Without oxygen, organisms can split glucose into just two molecules of pyruvate. This releases only enough energy to make two ATP molecules. With oxygen, organisms can break down glucose all the way to carbon dioxide. This releases enough energy to produce up to 38 ATP molecules. Thus, aerobic respiration releases much more energy than anaerobic respiration.
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.
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).
Animals eating these kinds of feeds have been shown to consume less dry matter and food energy. A problem called dry matter loss can result from heat generation, as caused by microbial respiration. It decreases the content of nonstructural carbohydrate, protein, and food energy.
Not all inhibitors of oxidative phosphorylation are toxins. In brown adipose tissue, regulated proton channels called uncoupling proteins can uncouple respiration from ATP synthesis. This rapid respiration produces heat, and is particularly important as a way of maintaining body temperature for hibernating animals, although these proteins may also have a more general function in cells' responses to stress.
With higher intensity training, breathing rate is increased in order to allow more air to move in and out of the lungs, which enhances gas exchange. Endurance training typically results in an increase in the respiration rate.
|
Major climate types are based on what two things?
|
[
"topography & temperature",
"environment & precipitation",
"temperature & precipitation",
"oxygen & precipitation"
] |
C
|
Major climate types are based on temperature and precipitation. These two factors determine what types of plants can grow in an area. Animals and other living things depend on plants. So each climate is associated with certain types of living things. A major type of climate and its living things make up a biome . As you read about the major climate types below, find them on the map in Figure above .
Climate classifications are systems that categorize the world's climates. A climate classification may correlate closely with a biome classification, as climate is a major influence on life in a region. One of the most used is the Köppen climate classification scheme first developed in 1899.There are several ways to classify climates into similar regimes. Originally, climes were defined in Ancient Greece to describe the weather depending upon a location's latitude.
Various factors affect the average state of the atmosphere at a particular location. For instance, midlatitudes will have a pronounced seasonal cycle of temperature whereas tropical regions show little variation of temperature over a year. Another major variable of climate is continentality: the distance to major water bodies such as oceans. Oceans act as a moderating factor, so that land close to it has typically less difference of temperature between winter and summer than areas further from it. The atmosphere interacts with other parts of the climate system, with winds generating ocean currents that transport heat around the globe.
Ocean currents are another important factor in determining climate, particularly the major underwater thermohaline circulation which distributes heat energy from the equatorial oceans to the polar regions. These currents help to moderate the differences in temperature between winter and summer in the temperate zones. Also, without the redistributions of heat energy by the ocean currents and atmosphere, the tropics would be much hotter, and the polar regions much colder.
A detailed comparison between some national climate projections have been carried out.
The climate type's name is in reference to the coastal regions of the Mediterranean Sea, which mostly share this type of climate, but it can also be found in the Atlantic portions of Iberia and Northwest Africa, the Pacific portions of the United States and Chile, extreme west areas of Argentina, around Cape Town, South Africa, parts of Southwest and South Australia and parts of Central Asia. Mediterranean climate zones are typically located along the western coasts of landmasses, between roughly 30 and 45 degrees north or south of the equator. The main cause of Mediterranean, or dry summer, climate is the subtropical ridge, which extends towards the pole of the hemisphere in question during the summer and migrates towards the equator during the winter.
|
When amino acids bind together, they form a long chain called what, which is an essential component of protein?
|
[
"peptide",
"polypeptide",
"lipids",
"enzyme"
] |
B
|
When amino acids bind together, they form a long chain called a polypeptide . A protein consists of one or more polypeptide chains. A protein may have up to four levels of structure. The lowest level, a protein’s primary structure, is its sequence of amino acids. Higher levels of protein structure are described in Figure below . The complex structures of different proteins give them unique properties, which they need to carry out their various jobs in living organisms. You can learn more about protein structure by watching the animation at the following link: http://www. stolaf. edu/people/giannini/flashanimat/proteins/protein%20structure. swf .
Once a polypeptide chain is fully folded, it is called a protein. Often many subunits will combine to make a fully functional protein although physiological proteins do exist that contain only one polypeptide chain. Proteins may also incorporate other molecules such as the heme group in hemoglobin, a protein responsible for carrying oxygen in the blood.
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.
This pathway is not present in humans or other animals, however. The lack of this pathway means that humans need to take in these amino acids through their diet, which is why they are called essential amino acids. == References ==
Five amino acids possess a charge at neutral pH. Often these side chains appear at the surfaces on proteins to enable their solubility in water, and side chains with opposite charges form important electrostatic contacts called salt bridges that maintain structures within a single protein or between interfacing proteins. Many proteins bind metal into their structures specifically, and these interactions are commonly mediated by charged side chains such as aspartate, glutamate and histidine. The two negatively charged amino acids at neutral pH are aspartate (Asp, D) and glutamate (Glu, E).
While the amino acid members of the triad are located far from one another on the sequence of the protein, due to folding, they will be very close to one another in the heart of the enzyme. The particular geometry of the triad members are highly characteristic to their specific function: it was shown that the position of just four points of the triad characterize the function of the containing enzyme.In the event of catalysis, an ordered mechanism occurs in which several intermediates are generated. The catalysis of the peptide cleavage can be seen as a ping-pong catalysis, in which a substrate binds (in this case, the polypeptide being cleaved), a product is released (the N-terminus "half" of the peptide), another substrate binds (in this case, water), and another product is released (the C-terminus "half" of the peptide).
|
What type of cells does meiosis produce?
|
[
"child cells",
"haploid daughter cells",
"diploid daughter cells",
"mutated cells"
] |
B
|
Meiosis is a special type of cell division. It produces haploid daughter cells. It occurs when an organism makes gametes. Meiosis is basically mitosis times two. The original diploid cell divides twice. The first time is called meiosis I. The second time is called meiosis II. However, the DNA replicates only once. It replicates before meiosis I but not before meiosis II. This results in four haploid daughter cells.
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.
M phase See mitosis. meiosis A specialized type of cell division which occurs exclusively in sexually reproducing eukaryotes, during which DNA replication is followed by two consecutive rounds of cell division to ultimately produce four genetically unique daughter cells, each with half the number of chromosomes as the original parent cell. 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.
A meiocyte is a type of cell that differentiates into a gamete through the process of meiosis. Through meiosis, the diploid meiocyte divides into four genetically different haploid gametes. The control of the meiocyte through the meiotic cell cycle varies between different groups of organisms.
For example, most animals are diploid and produce haploid gametes. During meiosis, sex cell precursors have their number of chromosomes halved by randomly "choosing" one member of each pair of chromosomes, resulting in haploid gametes.
Homologous chromosomes contain highly similar but not identical information, and by exchanging similar but not identical regions, genetic recombination increases genetic diversity among future generations.During sexual reproduction, two haploid gametes combine into one diploid cell known as a zygote in a process called fertilization. The nuclei from the gametes fuse, and each gamete contributes half of the genetic material of the zygote. Multiple cell divisions by mitosis (without change in the number of chromosomes) then develop into a multicellular diploid phase or generation.
|
Organisms that lack both a nucleus and membrane-bound organelles are known as what, in general?
|
[
"photosynthetic",
"barren",
"prokaryotic",
"trophic"
] |
C
|
Two of the three domains—Bacteria and Archaea—are prokaryotic, meaning that they lack both a nucleus and true membrane-bound organelles. However, they are now considered, on the basis of membrane structure and rRNA, to be as different from each other as they are from the third domain, the Eukarya. Prokaryotes were the first inhabitants on Earth, perhaps appearing approximately 3.9 billion years ago. Today they are ubiquitous—inhabiting the harshest environments on the planet, from boiling hot springs to permanently frozen environments in Antarctica, as well as more benign environments such as compost heaps, soils, ocean waters, and the guts of animals (including humans). The Eukarya include the familiar kingdoms of animals, plants, and fungi. They also include a diverse group of kingdoms formerly grouped together as protists.
Eukaryotes have a nucleus where DNA is contained. They are usually larger than prokaryotes and contain many more organelles. The nucleus, the feature of a eukaryote that distinguishes it from a prokaryote, contains a nuclear envelope, nucleolus and chromatin. In cytoplasm, endoplasmic reticulum (ER) synthesizes membranes and performs other metabolic activities.
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name organelle comes from the idea that these structures are parts of cells, as organs are to the body, hence organelle, the suffix -elle being a diminutive. Organelles are either separately enclosed within their own lipid bilayers (also called membrane-bound organelles) or are spatially distinct functional units without a surrounding lipid bilayer (non-membrane bound organelles). Although most organelles are functional units within cells, some function units that extend outside of cells are often termed organelles, such as cilia, the flagellum and archaellum, and the trichocyst.
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.
A mitosome is an organelle found in some unicellular eukaryotic organisms, like in members of the supergroup Excavata. The mitosome was found and named in 1999, and its function has not yet been well characterized. It was termed a crypton by one group, but that name is no longer in use. The mitosome has been detected only in anaerobic or microaerophilic organisms that do not have mitochondria.
In addition to the chromosomes in the nucleus, organelles such as the chloroplasts and mitochondria have their own DNA. Mitochondria are sometimes said to have their own genome often referred to as the "mitochondrial genome". The DNA found within the chloroplast may be referred to as the "plastome".
|
What happens to most of the energy in a trophic level as it passes to the next higher level?
|
[
"it increases",
"it is transferred",
"it stays the same",
"it is lost"
] |
D
|
When energy is transferred from one trophic level to the next, typically only ten percent is used to build new biomass. The remaining ninety percent goes to metabolic processes or is dissipated as heat. This energy loss means that productivity pyramids are never inverted, and generally limits food chains to about six levels. However, in oceans, biomass pyramids can be wholly or partially inverted, with more biomass at higher levels.
The concept of trophic levels are used in food webs to visualise the manner in which energy is transferred from one part of an ecosystem to another. Trophic levels can be assigned numbers determining how far an organism is along the food chain. Level one: Producers, plant-like organisms that generate their own food using solar radiation, including algae, phytoplankton, mosses and lichens.
The P/B ratio utilizes inverse time units (example: 1/month). This ratio allows for an estimate of the amount of energy flow compared to the amount of biomass at a given trophic level, allowing for demarcations to be made between trophic levels. The P/B ratio most commonly decreases as trophic level and organismal size increases, with small, ephemeral organisms containing a higher P/B ratio than large, long-lasting ones.
This level is only known statistically, and may vary for reasons which are not well understood. The level of supersaturation limited by controlling the speed of ascent and making periodic stops to allow gases to be eliminated by respiration.
This selection occurs most strongly in the endosphere, followed by the rhizoplane, and finally the rhizosphere. For example, root exudates can select for and promote the growth of certain beneficial microbes by serving as carbon and/or energy sources for microbial metabolism.
|
What is the name for a specific amount of solute that can dissolve in a given amount of solvent?
|
[
"humidity",
"viscosity",
"concentration",
"solubility"
] |
D
|
Solubility is a specific amount of solute that can dissolve in a given amount of solvent.
Usually, the substance present in the greatest amount is considered the solvent. Solvents can be gases, liquids, or solids. One or more components present in the solution other than the solvent are called solutes. The solution has the same physical state as the solvent.
A variation of the static method is to add a solution of the substance in a non-aqueous solvent, such as dimethyl sulfoxide, to an aqueous buffer mixture. Immediate precipitation may occur giving a cloudy mixture. The solubility measured for such a mixture is known as "kinetic solubility".
As the solvent composition changes due to an increase in the solvent that has gas diffused into the solution, the compound becomes increasingly insoluble in the solution and crystallizes.Interface/slow mixing (often performed in an NMR tube). Similar to the above, but instead of one solvent gas-diffusing into another, the two solvents mix (diffuse) by liquid-liquid diffusion. Typically a second solvent is "layered" carefully on top of the solution containing the compound.
A solution is a homogeneous mixture of two or more substances. The particles of solute in a solution cannot be seen by the naked eye. By contrast, particles may be visible in a suspension. A solution does not cause beams of light to scatter.
A solvent is a substance that is liquid at the temperature at which it is used. It has the ability to dissolve, dilute or extract other substances without changing them chemically and without changing itself. The traditional organic solvents (acetone, NMP, toluene, etc.), although very effective, raise today many problems as they are associated with adverse effects, both on the health and safety of workers (burns, cancer, eczema, brain disorder (encephalopathy), fetotoxicity (via the placenta), and inflammations of several peripheral nerves at the same time, as well as on the environment and health of the general population (smog precursors, water, air and ozone layer pollution). Solvents represent a major part of the chemical use in various domains (paints, coating, synthesis, ...) and in consequence define a lot of the environmental performance of the chemical industry.
|
What is freshwater below the earth's surface called?
|
[
"geyser",
"sediment",
"precipitation",
"groundwater"
] |
D
|
Freshwater below Earth’s surface is called groundwater . The water infiltrates, or seeps down into, the ground from the surface. How does this happen? And where does the water go?.
The remaining unfrozen freshwater is mainly found as groundwater, with only a small fraction present in the air, or on the ground surface. Surface water is stored in wetlands or lakes or flows in a stream or river, and is the most commonly utilized resource for water. In places, surface water can be stored in a reservoir behind a dam, and then used for municipal and industrial water supply, for irrigation and to generate power in the form of hydroelectricity.
In an arid region, rainwater sinks into the ground very quickly. Later, as the surface dries out, the water below the surface rises, carrying up dissolved minerals from lower layers. These precipitate as water evaporates and carbon dioxide is lost.
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.
Where the water table is below the land surface, its depth reflects the minimum level to which wells must be drilled for groundwater extraction; a spring occurs where it reaches the land surface, and a permanent marsh or lake results where the theoretical water table is above the land surface. The level of the water table is the boundary between the vadose zone and the phreatic zone. Its depth fluctuates seasonally, which accounts for the intermittent flow of bournes.
Most of Earth's land is somewhat humid and covered by vegetation, while large sheets of ice at Earth's polar deserts retain more water than Earth's groundwater, lakes, rivers and atmospheric water together. Earth's land is part of Earth's crust, consisting of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Inside Earth's crust is a liquid outer core that generates the magnetosphere, deflecting most of the destructive solar winds and cosmic radiation.
|
What forms when crystals precipitate out from a liquid?
|
[
"liquid sedimentary rocks",
"chemical sedimentary rocks",
"plasma sedimentary rocks",
"plants sedimentary rocks"
] |
B
|
Chemical sedimentary rocks form when crystals precipitate out from a liquid. The mineral halite, also called rock salt, forms this way. You can make halite! Leave a shallow dish of salt water out in the Sun. As the water evaporates, salt crystals form in the dish. There are other chemical sedimentary rocks, like gypsum.
Calcium carbonate is known to precipitate as calcite crystals in water supersaturated with calcium and carbonate ions. Under quiescent conditions, calcite crystals can form on a water surface when calcium carbonate supersaturation conditions do not exist in the bulk water. Water evaporates from the surface and carbon dioxide degasses from the surface layer to create a thin layer of water with high pH and concentrations of calcium and carbonate ions far above the saturation concentration for calcium carbonate.
The most common way to form an ice crystal starts with an ice nucleus in the cloud. Ice crystals can form from heterogeneous deposition, contact, immersion, or freezing after condensation. In heterogeneous deposition, an ice nucleus is simply coated with water. For contact, ice nuclei will collide with water droplets that freeze upon impact.
Cumulate rocks are the typical product of precipitation of solid crystals from a fractionating magma chamber. These accumulations typically occur on the floor of the magma chamber, although they are possible on the roofs if anorthite plagioclase is able to float free of a denser mafic melt.Cumulates are typically found in ultramafic intrusions, in the base of large ultramafic lava tubes in komatiite and magnesium rich basalt flows and also in some granitic intrusions.
Precipitate formation is useful in the detection of the type of cation in a salt. To do this, an alkali first reacts with the unknown salt to produce a precipitate that is the hydroxide of the unknown salt. To identify the cation, the color of the precipitate and its solubility in excess are noted. Similar processes are often used in sequence – for example, a barium nitrate solution will react with sulfate ions to form a solid barium sulfate precipitate, indicating that it is likely that sulfate ions are present.
Commonly it has no definite form of its own, but fills up the irregular interspaces between the earlier crystallized minerals. The compositions of these residual crystallization products may represent eutectic compositions, the mixtures (quartz plus feldspar plus minor amounts of other minerals) which have the lowest fusion point. The texture may commonly form in the presence of a vapor phase as well as a silicate melt, however, and vapor-rock reactions below the solidus may result in feldspar replacement and consequent compositional changes.
|
What do people build to protect areas from floods?
|
[
"reinforced walls",
"dams",
"drains",
"sewers"
] |
B
|
People protect areas that might flood with dams. In dire situations, they use sandbags ( Figure below ). Dams are usually very effective, but high water levels sometimes cause a dam to break. In that case, flooding can be catastrophic. Flood waters can also overflow a dam. People may line a river bank with levees to protect against floods. These are high walls that keep the stream within its banks during floods. Flood protection in one location sometimes causes problems elsewhere. For example, a levee in one location may just force the high water upstream or downstream. This will lead to flooding in a different location. Sometimes water gets so high that the river must be allowed to flood.
To prevent or manage coastal flooding, coastal management practices have to handle natural processes like tides but also the human cased sea level rise. Flood control and relief is a particularly important part of climate change adaptation and climate resilience, both sea level rise and changes in the weather (climate change causes more intense and quicker rainfall), means that flooding of human infrastructure is particularly important the world over.In environmental engineering, flood control involves the management of flood water movement, such as redirecting flood run-off through the use of floodwalls and flood gates, rather than trying to prevent floods altogether. It also involves the management of people, through measures such as evacuation and dry/wet proofing properties. The prevention and mitigation of flooding can be studied on three levels: on individual properties, small communities, and whole towns or cities.
Some prolonged high floods can delay traffic in areas which lack elevated roadways. Floods can interfere with drainage and economical use of lands, such as interfering with farming. Structural damage can occur in bridge abutments, bank lines, sewer lines, and other structures within floodways.
Water can produce a natural disaster in the form of tsunamis, hurricanes, rogue waves and storm surge. Land-based floods can originate from infrastructural issues like bursting dams or levee failure during surges, as well as environmental phenomena like rivers overflowing their banks during increased rainfall events, urban stormwater flooding, or snowmelt. The increased magnitude and frequency of floods are a result of urbanization and climate change. Urbanization increases stormwater runoff during large rain events.
With climate change intensifying, heavy storms are becoming more frequent and so is the increasing risk of flooding and sewer system overflows. According to the EPA, the average size of a 100-year floodplain is likely to increase by 45% in the next ten years. Another growing problem is urban flooding being caused by too much rain on impervious surfaces, urban floods can destroy neighborhoods. They particularly affect minority and low-income neighborhoods and can leave behind health problems like asthma and illness caused by mold. Green infrastructure reduces flood risks and bolsters the climate resiliency of communities by keeping rain out of sewers and waterways, capturing it where it falls.
With normally-open storm-surge gates, barriers alone will not address sea level rise, but neither will local shoreline storm-surge projects planned by New York City, which will also have gates. The SIRR report, itself, found that by the 2050s 43 miles, or about 8%, of the city's coastline could be at risk of flooding during non-storm conditions. These coastal areas will need to be raised or otherwise protected regardless of additional protections against storm surge.The two-tiered approach of protecting local coastal areas against slowly changing sea level rise, together with 25-foot offshore barriers to hold back surges of future storms, will give future civic leaders 100 to 150 years to protect, and if necessary migrate, our urban metropolitan civilization to higher ground, and to adopt even more sweeping measures to protect the region from both sea level rise and storm surges.Another objection to barriers is that restored natural systems, such as created wetlands and oyster beds could provide the same protection.
|
What system of the body is responsible for ultimately ridding it of waste and excess water?
|
[
"circulatory system",
"digestive system",
"excretory system",
"respiratory system"
] |
C
|
Toxic waste must be disposed of properly or there can be serious consequences. Now, your waste should not be as colorful or toxic as shown here (if it is, get yourself to a doctor as soon as possible), but it still needs to be removed from you. And that is the role of the excretory system. The excretory system gets rid of waste and excess water.
Through this process of eating the detritus many times over and harvesting the microorganisms from it, the detritus thins out, becomes fractured and becomes easier for the microorganisms to use, and so the complex carbohydrates are also steadily broken down and disappear over time. What is left behind by the detritivores is then further broken down and recycled by decomposers, such as bacteria and fungi. This detritus cycle plays a large part in the so-called purification process, whereby organic materials carried in by rivers is broken down and disappears, and an extremely important part in the breeding and growth of marine resources. In ecosystems on land, far more essential material is broken down as dead material passing through the detritus chain than is broken down by being eaten by animals in a living state. In both land and aquatic ecosystems, the role played by detritus is too large to ignore.
The nervous system consists of two nerve cords which run the length of the body, with two ganglia and two transverse commissures in most of the body segments.Gas exchange is thought to take place through the entire body surface, but especially that of the phyllopodia and their associated gills, which may also be responsible for osmotic regulation. Two coiled glands at the bases of the maxillae are used to excrete nitrogenous waste, typically in the form of urea. Most of the animal's nitrogenous waste is, however, in the form of ammonia, which probably diffuses into the environment through the phyllopodia and gills.
The term "human waste" is used in the general media to mean several things, such as sewage, sewage sludge, blackwater - in fact anything that may contain some human faeces. In the stricter sense of the term, human waste is in fact human excreta, i.e. urine and faeces, with or without water being mixed in. For example, dry toilets collect human waste without the addition of water.
Liquid waste is an important category of waste management because it is so difficult to deal with. Unlike solid wastes, liquid wastes cannot be easily picked up and removed from an environment. Liquid wastes spread out, and easily pollute other sources of liquid if brought into contact. This type of waste also soaks into objects like soil and groundwater. This in turn carries over to pollute the plants, the animals in the ecosystem, as well as the humans within the area of the pollution.
One of the main roles of the kidneys in humans and other mammals is to aid in the clearance of various water-soluble molecules, including toxins, toxicants, and metabolic waste. The body excretes some of these waste molecules via urination, and the role of the kidney is to concentrate the urine, such that waste molecules can be excreted with minimal loss of water and nutrients. The concentration of the excreted molecules determines the urine's specific gravity. In adult humans, normal specific gravity values range from 1.010 to 1.030.
|
What's it called when there's a sudden flow of mud?
|
[
"mudflow",
"avalanche",
"sediment",
"dirt bath"
] |
A
|
A mudflow is the sudden flow of mud down a slope because of gravity. Mudflows occur where the soil is mostly clay. Like landslides, mudflows usually occur when the soil is wet. Wet clay forms very slippery mud that slides easily. Mudflows follow river channels, washing out bridges, trees, and homes that are in their path.
This occurs in situations where liquids may infiltrate or are added to a draining system, such as might happen in a large sports venue. Examples of how this could occur include rain water infiltration. == References ==
mudflat Also mud flat and tidal flat. A type of coastal wetland consisting of exposed layers of bay mud formed by the deposition of silts, clays, and marine animal detritus by tides or rivers. Mudflats usually form within the intertidal zone of relatively sheltered areas such as bays and lagoons.
Landslide deposits are poorly sorted. Those rich in clay may show stretched clay lumps (a phenomenon called boudinage) and zones of concentrated shear.Debris flow deposits take the form of long, narrow tracks of very poorly sorted material. These may have natural levees at the sides of the tracks, and sometimes consist of lenses of rock fragments alternating with lenses of fine-grained earthy material. Debris flows often form much of the upper slopes of alluvial fans.
Overland flow can erode soil particles and transport them downslope. The erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions. If the initial impact of rain droplets dislodges soil, the phenomenon is called rainsplash erosion. If overland flow is directly responsible for sediment entrainment but does not form gullies, it is called "sheet erosion". If the flow and the substrate permit channelization, gullies may form; this is termed "gully erosion".
When the ground is partly dried, a salt crust forms over soft mud or hollow cavities, and a vehicle will become stuck after breaking through the crust. Here are two current examples of dune fields being flooded. The first is not a desert, but a coastal dune field in the Amazon region, flooded by heavy rains. The second is a dry inland desert in the Gobi region, flooded by ground water from nearby mountains.
|
Which zone is located below 200 meters from the surface?
|
[
"aphotic zone",
"epipelagic",
"observable zone",
"mesopelagic"
] |
A
|
Below 200 meters is the aphotic zone. There are no primary producers here because there isn’t enough sunlight for photosynthesis. However, the water may be rich in nutrients because of dead organisms drifting down from above. Organisms that live here may include bacteria, sponges, sea anemones, worms, sea stars, and fish.
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.
This leads to the distinction of the Earth's surface into a water and land hemisphere, as well as the division of the ocean into different oceans. Seawater covers about 361,000,000 km2 (139,000,000 sq mi) and the Ocean's furthest pole of inaccessibility, known as "Point Nemo", in a region known as spacecraft cemetery of the South Pacific Ocean, at 48°52.6′S 123°23.6′W. This point is roughly 2,688 km (1,670 mi) from the nearest land.
Its lowermost boundary is at a thermocline of 12 °C (54 °F), which, in the tropics generally lies between 200 and 1000 meters.The euphotic zone is somewhat arbitrarily defined as extending from the surface to the depth where the light intensity is approximately 0.1–1% of surface sunlight irradiance, depending on season, latitude and degree of water turbidity. In the clearest ocean water, the euphotic zone may extend to a depth of about 150 meters, or rarely, up to 200 meters. Dissolved substances and solid particles absorb and scatter light, and in coastal regions the high concentration of these substances causes light to be attenuated rapidly with depth.
The maximum "northing" value is about 9300000 meters at latitude 84 degrees North, the north end of the UTM zones. The southern hemisphere's northing at the equator is set at 10000000 meters. Northings decrease southward from these 10000000 meters to about 1100000 meters at 80 degrees South, the south end of the UTM zones.
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.
|
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