Split (1)

test · 389k rows

questions stringlengths 37 1.22k	reasoning stringlengths 0 3.56k ⌀	answers stringlengths 4 138
What type of energy is required in all chemical reactions? Here are the choices: A. solar B. activation C. conduction D. function	All chemical reactions require activation energy, which is the energy needed to get a reaction started.	B: activation.
What type of image is formed when light rays diverge in front of a mirror? Here are the choices: A. large B. reversed C. virtual D. fake	When light rays diverge in front of a mirror, a virtual image is formed. A virtual image is formed by your brain tracing diverging rays backwards and is kind of a trick, like the person you see “behind” a mirror’s surface when you brush your teeth (there's obviously no real light focused behind a mirror!). Since virtual images aren’t actually “anywhere,” you can’t place photographic film anywhere to capture them.	C: virtual.
What is the condition of a plant in which the fluid in a cell exerts a pressure against the cell wall? Here are the choices: A. hydration B. constriction C. turgor D. tumor	called the relative osmotic pressure if neither solution is pure water, and it is called the osmotic pressure if one solution is pure water. Osmotic pressure can be large, depending on the size of the concentration difference. For example, if pure water and sea water are separated by a semipermeable membrane that passes no salt, osmotic pressure will be 25.9 atm. This value means that water will diffuse through the membrane until the salt water surface rises 268 m above the pure-water surface! One example of pressure created by osmosis is turgor in plants (many wilt when too dry). Turgor describes the condition of a plant in which the fluid in a cell exerts a pressure against the cell wall. This pressure gives the plant support. Dialysis can similarly cause substantial pressures.	C: turgor.
What phenomenon, crucial for evolution, creates new genetic variation in a gene pool and is how all new alleles first arise? Here are the choices: A. radiation B. adaptation C. mutation D. natural selection	Mutation creates new genetic variation in a gene pool. It is how all new alleles first arise. In sexually reproducing species, the mutations that matter for evolution are those that occur in gametes. Only these mutations can be passed to offspring. For any given gene, the chance of a mutation occurring in a given gamete is very low. Thus, mutations alone do not have much effect on allele frequencies. However, mutations provide the genetic variation needed for other forces of evolution to act.	C: mutation.
What is the name of the stage of life when a child becomes sexually mature? Here are the choices: A. reproductive stage B. puberty C. pre-adolescence D. adulthood	Puberty is the stage of life when a child becomes sexually mature. Puberty begins when the pituitary gland tells the testes to secrete testosterone in boys, and in girls the pituitary gland signals the ovaries to secrete estrogen. Changes that occur during puberty are discussed in the Male Reproductive Development and Female Reproductive Development concepts.	B: puberty.
A man made lake is known as what? Here are the choices: A. Lake B. Lagoon C. Pond D. resevoirs	Many lakes are not natural, but are human-made. People dam a stream in a suitable spot. Water backs up behind the dam, creating a lake. These lakes are "reservoirs" ( Figure below ).	D: resevoirs.
Alchemy helped improve the study of metallurgy and the extraction of metals from what? Here are the choices: A. wood B. water C. air D. ores	However, out of all this secrecy came several contributions to modern-day chemistry. Early acids and bases were discovered. Glassware for running chemical reactions was developed. Alchemy helped improve the study of metallurgy and the extraction of metals from ores. More systematic approaches to research were being developed, although the idea of orderly scientific experimentation had not become well-established yet. But the groundwork was laid to the development of chemistry as a foundational science.	D: ores.
What are the two types of vascular tissues? Here are the choices: A. ganglia and phloem B. xylem and phloem C. ectoderm and phloem D. epidermis and phloem	Vascular tissue runs through the ground tissue inside a plant. It transports fluids throughout the plant. Vascular tissue actually consists of two types of tissues, called xylem and phloem. The two types of vascular tissue are packaged together in bundles. You can see them in the celery in Figure below .	B: xylem and phloem.
The spinal cord develops, cells making up the wall of the neural tube proliferate and differentiate into what? Here are the choices: A. jelly and glia B. neurons and glia C. muscles and glia D. membrane and glia	Spinal Cord Development While the brain is developing from the anterior neural tube, the spinal cord is developing from the posterior neural tube. However, its structure does not differ from the basic layout of the neural tube. It is a long, straight cord with a small, hollow space down the center. The neural tube is defined in terms of its anterior versus posterior portions, but it also has a dorsal–ventral dimension. As the neural tube separates from the rest of the ectoderm, the side closest to the surface is dorsal, and the deeper side is ventral. As the spinal cord develops, the cells making up the wall of the neural tube proliferate and differentiate into the neurons and glia of the spinal cord. The dorsal tissues will be associated with sensory functions, and the ventral tissues will be associated with motor functions.	B: neurons and glia.
Eventually the parent cell will pinch apart to form two identical types of what cells? Here are the choices: A. father cells B. son cells C. daughter cells D. brother cells	Cell division is relatively simple in prokaryotic cells. The two cells divide by binary fission. Green and orange lines indicate old and newly-generated bacterial cell walls, respectively. Eventually the parent cell will pinch apart to form two identical daughter cells. Left, growth at the center of bacterial body, such as in Bacillus subtilis and E. coli . Right, apical growth from the ends of the bacterial body, such as in Corynebacterium diphtheriae .	C: daughter cells.
The body cells cannot use insulin properly in which type of diabetes? Here are the choices: A. type 3 diabates B. type 2 diabetes C. type 1 diabetes D. type 4 diabetes	In type 2 diabetes, the body cells cannot use insulin properly.	B: type 2 diabetes.
Birds belong to a group of diapsids called the what? Here are the choices: A. conifers B. mammals C. archosaurs D. aviators	Evolution of Birds The evolutionary history of birds is still somewhat unclear. Due to the fragility of bird bones, they do not fossilize as well as other vertebrates. Birds are diapsids, meaning they have two fenestrations or openings in their skulls. Birds belong to a group of diapsids called the archosaurs, which also includes crocodiles and dinosaurs. It is commonly accepted that birds evolved from dinosaurs. Dinosaurs (including birds) are further subdivided into two groups, the Saurischia (“lizard like”) and the Ornithischia (“bird like”). Despite the names of these groups, it was not the bird-like dinosaurs that gave rise to modern birds. Rather, Saurischia diverged into two groups: One included the long-necked herbivorous dinosaurs, such as Apatosaurus. The second group, bipedal predators called theropods, includes birds. This course of evolution is suggested by similarities between theropod.	C: archosaurs.
How many limbs to birds have? Here are the choices: A. six B. four C. ten D. five	Birds are four-limbed, endothermic vertebrates with wings and feathers. They produce amniotic eggs and are the most numerous class of vertebrates.	B: four.
Planes fly in what layer of the atmosphere because there is less friction and turbulence? Here are the choices: A. stratosphere B. mesosphere C. ozone layer D. crust	Sure we can! If you've ever flown on a jet airplane, you've been in the stratosphere. Airplanes fly in the stratosphere, because there is less friction. They get better gas mileage and so costs are lower. There is also less turbulence, so passengers are happier. Can you identify the bottom of the stratosphere in the photo? It's where the clouds begin. Remember that all weather is in the troposphere.	A: stratosphere.
What is a group of similar ecosystems with the same general abiotic factors and primary producers? Here are the choices: A. family B. biome C. ecoregion D. taxon	The two photos in Figure above represent two different biomes. A biome is a group of similar ecosystems with the same general abiotic factors and primary producers. Producers are organisms that produce food for themselves and other organisms. Biomes may be terrestrial or aquatic.	B: biome.
Interferons are produced in virally infected cells and cause them to secrete signals for surrounding cells to make what? Here are the choices: A. resist proteins B. antiviral proteins C. Raising Proteins D. overwhelm proteins	Chapter 21 1 The three main components are the lymph vessels, the lymph nodes, and the lymph. 3 The bacterium is digested by the phagocyte’s digestive enzymes (contained in its lysosomes). 5 B 7 C 9 A 11 D 13 C 15 B 17 B 19 D 21 D 23 B 25 C 27 B 29 C 31 D 33 A 35 B 37 B 39 The lymph enters through lymphatic capillaries, and then into larger lymphatic vessels. The lymph can only go in one direction due to valves in the vessels. The larger lymphatics merge to form trunks that enter into the blood via lymphatic ducts. 41 Interferons are produced in virally infected cells and cause them to secrete signals for surrounding cells to make antiviral proteins. C-reactive protein is induced to be made by the liver and will opsonize certain species of bacteria. 43 Antigen-specific clones are stimulated as their antigen receptor binds to antigen. They are then activated and proliferate, expanding their numbers. The result is a large number of antigen-specific lymphocytes. 45 IgM is an antigen receptor on naïve B cells. Upon activation, naïve B cells make IgM first. IgM is good at binding complement and thus has good antibacterial effects. IgM is replaced with other classes of antibodies later on in the primary response due to class switching. 47 Tuberculosis is caused by bacteria resistant to lysosomal enzymes in alveolar macrophages, resulting in chronic infection. The immune response to these bacteria actually causes most of the lung damage that is characteristic of this life-threatening disease. 49 Antibody response to the cell walls of β-Streptococcus cross-reacts with the heart muscle. Complement is then activated and the heart is damaged, leading to abnormal function. Tolerance is broken because heart myosin antigens are similar to antigens on the β- Streptococcus bacteria.	B: antiviral proteins.
What slow process is required for formation of soil? Here are the choices: A. digestion B. weathering C. leaching D. fossilization	Soil formation requires weathering. Where there is less weathering, soils are thinner. However, soluble minerals may be present. Where there is intense weathering, soils may be thick. Minerals and nutrients would have been washed out. Soil development takes a very long time. It may take hundreds or even thousands of years to form the fertile upper layer of soil. Soil scientists estimate that in the very best soil forming conditions, soil forms at a rate of about 1mm/year. In poor conditions, it may take thousands of years!.	B: weathering.
What is defined as superheated gas with a positive electrical charge? Here are the choices: A. ion B. plasma C. greenhouse gas D. supernova	The Sun is made mostly of plasma. Plasma is superheated gas with a positive electrical charge.	B: plasma.
Materials, such as iron, that exhibit strong magnetic effects are labeled what? Here are the choices: A. ferromagnetic B. paramagnetic C. ultramagnetic D. superconducting	Magnetic poles always occur in pairs of north and south—it is not possible to isolate north and south poles. All magnetism is created by electric current. Ferromagnetic materials, such as iron, are those that exhibit strong magnetic effects. The atoms in ferromagnetic materials act like small magnets (due to currents within the atoms) and can be aligned, usually in millimeter-sized regions called domains. • Domains can grow and align on a larger scale, producing permanent magnets. Such a material is magnetized, or induced to be magnetic. • Above a material’s Curie temperature, thermal agitation destroys the alignment of atoms, and ferromagnetism disappears. • Electromagnets employ electric currents to make magnetic fields, often aided by induced fields in ferromagnetic materials.	A: ferromagnetic.
Like birds, most other reptiles excrete their nitrogenous wastes as what acid? Here are the choices: A. sulphuric B. uric C. hydrochloric D. lactic		B: uric.
The two main fundamental particles that make up neutrons are quarks and what else? Here are the choices: A. prions B. leptons C. gluons D. atoms	Neutrons consist of fundamental particles known as quarks and gluons. Gluons carry the strong nuclear force that binds together the quarks in a neutron.	C: gluons.
Birds have evolved a respiratory system that enables them to fly. flying is a high-energy process and requires a lot of this? Here are the choices: A. oxygen B. nitrogen C. adaptation D. weight	Avian Respiration Birds have evolved a respiratory system that enables them to fly. Flying is a high-energy process and requires a lot of oxygen. Furthermore, many birds fly in high altitudes where the concentration of oxygen in low. How did birds evolve a respiratory system that is so unique? Decades of research by paleontologists have shown that birds evolved from therapods, meat-eating dinosaurs (Figure 39.14). In fact, fossil evidence shows that meat-eating dinosaurs that lived more than 100 million years ago had a similar flow-through respiratory system with lungs and air sacs. Archaeopteryx and Xiaotingia, for example, were flying dinosaurs and are believed to be early precursors of birds.	A: oxygen.
Lysosomes have what type of enzymes that break down old molecules into parts that can be recycled? Here are the choices: A. bacterial B. corrosive C. digestive D. probiotics	Lysosomes are like the recycling trucks that carry waste away from the factory. Lysosomes have digestive enzymes that break down old molecules into parts that can be recycled.	C: digestive.
The breasts contain what to give milk to feed a baby? Here are the choices: A. sebaceous glands B. fetal glands C. primordial glands D. mammary glands	The female reproductive organs include the vagina, uterus, fallopian tubes, and ovaries ( Figure below ). The breasts are not shown in this figure. They are not considered reproductive organs, even though they are involved in reproduction. They contain mammary glands that give milk to feed a baby. The milk leaves the breast through the nipple when the baby sucks on it.	D: mammary glands.
What form when water vapor condenses in the air around specs of matter? Here are the choices: A. humidity B. condensation C. clouds D. storms	Clouds form when water vapor condenses in the air around specs of matter. Clouds are classified on the basis of where and how they form. Types of clouds include cirrus, stratus, and cumulus clouds.	C: clouds.
All other forms of life, including plants and animals, are composed of what kind of cells? Here are the choices: A. bacterial B. cytoplasmic C. synthetic D. eukaryotic		D: eukaryotic.
A mycorrhiza refers to what kind of relationship between a fungus and the roots of a plant? Here are the choices: A. symbiotic B. familial C. semantic D. predator-prey	A mycorrhiza (Greek for "fungus roots") is a symbiotic association between a fungus and the roots of a plant. In a mycorrhizal association, the fungus may colonize the roots of a host plant by either growing directly into the root cells, or by growing around the root cells. This association provides the fungus with relatively constant and direct access to glucose, which the plant produces by photosynthesis. The mycelia of the fungi increase the surface area of the plant’s root system. The larger surface area improves water and mineral nutrient absorption from the soil.	A: symbiotic.
What is earth's main source of energy? Here are the choices: A. the core B. the atmosphere C. the sun D. the moon	The Sun is Earth’s main source of energy. The Sun gives us both light and heat. The Sun changes hydrogen into helium through nuclear fusion. This releases huge amounts of energy. The energy travels to the Earth mostly as visible light. The energy is carried through the empty space by radiation . We can use sunlight as an energy resource, called solar energy ( Figure above ).	C: the sun.
Kirchhoff’s second rule (the loop rule) is an application of conservation of what? Here are the choices: A. Rock B. energy C. mineral D. heating	Kirchhoff’s Second Rule Kirchhoff’s second rule (the loop rule) is an application of conservation of energy. The loop rule is stated in terms of potential, V , rather than potential energy, but the two are related since PE elec = qV . Recall that emf is the potential difference of a source when no current is flowing. In a closed loop, whatever energy is supplied by emf must be transferred into other forms by devices in the loop, since there are no other ways in which energy can be transferred into or out of the circuit. Figure 21.23 illustrates the changes in potential in a simple series circuit loop. Kirchhoff’s second rule requires emf equals the sum of the.	B: energy.
Evolution over a short period of time at the level of the population is called what? Here are the choices: A. grammaticalization B. redistributions C. macroevolution D. microevolution	The time scale of evolution can vary. Evolution over a short period of time at the level of the population is called microevolution. Evolution over a long period of time above the level of the species is called macroevolution.	D: microevolution.
When water is heated by magma and makes it's way to the surface what is created? Here are the choices: A. trough B. geyser C. eruption D. volcanic	Water works its way through porous rocks or soil. Sometimes this water is heated by nearby magma. If the water makes its way to the surface, it forms a hot spring or a geyser.	B: geyser.
The mechanical and digestive processes have one goal: to convert food into molecules small enough to be absorbed by the epithelial cells of what? Here are the choices: A. alveoli B. stomach cilia C. bile ducts D. intestinal villi	Absorption The mechanical and digestive processes have one goal: to convert food into molecules small enough to be absorbed by the epithelial cells of the intestinal villi. The absorptive capacity of the alimentary canal is almost endless. Each day, the alimentary canal processes up to 10 liters of food, liquids, and GI secretions, yet less than one liter enters the large intestine. Almost all ingested food, 80 percent of electrolytes, and 90 percent of water are absorbed in the small intestine. Although the entire small intestine is involved in the absorption of water and lipids, most absorption of carbohydrates and proteins occurs in the jejunum. Notably, bile salts and vitamin B12 are absorbed in the terminal ileum. By the time chyme passes from the ileum into the large intestine, it is essentially indigestible food residue (mainly plant fibers like cellulose), some water, and millions of bacteria (Figure 23.32).	D: intestinal villi.
Influenza virus is packaged in a viral envelope, which fuses with the what? Here are the choices: A. cell wall B. plasma membrane C. bacteria D. nucleus	Influenza virus is packaged in a viral envelope, which fuses with the plasma membrane. This way, the virus can exit the host cell without killing it. What advantage does the virus gain by keeping the host cell alive?.	B: plasma membrane.
A desert is a type of what community in an ecosystem? Here are the choices: A. colony B. culture C. population D. biome	This scene is from Anza-Borrago California Desert Park. However, deserts exist around the globe. You might find a similar picture of a desert in Africa. The desert is one type of biome.	D: biome.
What are the two types of properties that matter has? Here are the choices: A. size and shape B. nature and purpose C. composition and weight D. physical and chemical	Matter has both physical and chemical properties. Physical properties can be measured or observed without matter changing to a different substance.	D: physical and chemical.
What is the hormone produced in high-stress situations? Here are the choices: A. somatostatin B. thyroxine C. testosterone D. adrenalin	In the health sciences, the concentration of a solution is typically expressed asparts per thousand (ppt), indicated as a proportion. For example, adrenalin, the hormone produced in high-stress situations, is available in a 1:1000 solution, or one gram of adrenalin per 1000 g of solution. The labels on bottles of commercial reagents often describe the contents in terms of mass percentage. Sulfuric acid, for example, is sold as a 95% aqueous solution, or 95 g of H2SO4 per 100 g of solution. Parts per million and parts per billion are used to describe concentrations of highly dilute solutions. These measurements correspond to milligrams and micrograms of solute per kilogram of solution, respectively. For dilute aqueous solutions, this is equal to milligrams and micrograms of solute per liter of solution (assuming a density of 1.0 g/mL).	D: adrenalin.
What type of reaction causes two substances to combine to make a single substance? Here are the choices: A. composition reaction B. component reaction C. metabolism D. spontaneous mutation	In this equation, two substances combine to make a single substance. This is a composition reaction. Two different substances react to make two new substances. This does not fit the definition of either a composition reaction or a decomposition reaction, so it is neither. In fact, you may recognize this as a double-replacement reaction. A single substance reacts to make multiple substances. This is a decomposition reaction.	A: composition reaction.
Hay fever is actually an allergy to what substance, vital to plant reproduction? Here are the choices: A. grass B. fungi C. nitrogen D. pollen	Did you ever hear of hay fever? It’s not really a fever at all. It’s an allergy to plant pollens. People with this type of allergy have symptoms such as watery eyes, sneezing, and a runny nose. A common cause of hay fever is the pollen of ragweed. Many people are also allergic to poison ivy ( Figure below ). Skin contact with poison ivy leads to an itchy rash in people who are allergic to the plant.	D: pollen.
Endotherms are warmed mostly by heat generated by what? Here are the choices: A. metabolism B. electricity C. the sun D. movement		A: metabolism.
If a ball is released from rest when air resistance is negligible, velocity is seen to increase linearly, while what related property is a constant? Here are the choices: A. acceleration B. density C. time D. speed	Figure 2.43 Positions and velocities of a metal ball released from rest when air resistance is negligible. Velocity is seen to increase linearly with time while displacement increases with time squared. Acceleration is a constant and is equal to gravitational acceleration.	A: acceleration.
What term is used to describe the ability of matter to burn? Here are the choices: A. permeability B. flammability C. volatility D. reactivity	Flammability is the ability of matter to burn. When matter burns, it combines with oxygen and changes to different substances. Wood is an example of flammable matter, as seen in Figure below .	B: flammability.
What is the evolutionary history of group of related organisms Here are the choices: A. phylogeny B. history C. iteration D. substructure	Phylogeny is the evolutionary history of group of related organisms. It is represented by a phylogenetic tree that shows how species are related to each other through common ancestors.	A: phylogeny.
What forms a ketone when oxidized? Here are the choices: A. enzyme B. carbolic acid C. secondary alcohol D. aldehyde	A secondary alcohol forms a ketone when oxidized. The secondary alcohol cannot be further oxidized to produce a carboxylic acid. Tertiary alcohols cannot be oxidized in this way, because the carbon atom bonded to the OH group is not also bonded to any hydrogens.	C: secondary alcohol.
What is the energy that flows as a result of a difference in temperature? Here are the choices: A. polarity B. magnetism C. heat D. electricity	Heat is the energy that flows as a result of a difference in temperature. We use the symbol for heat. Heat, like all forms of energy, is measured in joules.	C: heat.
Exposure to toxins is most damaging during weeks 4 through 8 of the embryonic stage due to development of what during this period? Here are the choices: A. faith B. pain C. organs D. samples	Embryonic Development (Weeks 4–8). Most organs develop in the embryo during weeks 4 through 8. If the embryo is exposed to toxins during this period, the effects are likely to be very damaging. Can you explain why? (Note: the drawings of the embryos are not to scale. ).	C: organs.
What evolutionary process may affect the distribution of a polygenic trait? Here are the choices: A. natural selection B. flow selection C. artificial selection D. characteristic selection	Natural Selection for a Polygenic Trait. Natural selection may affect the distribution of a polygenic trait. These graphs show three ways this can happen.	A: natural selection.
What type of force exists between two touching surfaces? Here are the choices: A. opposing B. tension C. friction D. centrifugal	Friction is the force that resists motion. In most beginning physics classes, friction is ignored. Concepts can be understood and calculations made assuming friction to be nonexistent. Whenever physics intersects with the real world, however, friction must be taken into account. Friction exists between two touching surfaces because even the smoothest looking surface is quite rough on a microscopic scale.	C: friction.
A short reflex is completely what and only involves the local integration of sensory input with motor output? Here are the choices: A. neuronal B. peripheral C. physiological D. central	Short and Long Reflexes Somatic reflexes involve sensory neurons that connect sensory receptors to the CNS and motor neurons that project back out to the skeletal muscles. Visceral reflexes that involve the thoracolumbar or craniosacral systems share similar connections. However, there are reflexes that do not need to involve any CNS components. A long reflex has afferent branches that enter the spinal cord or brain and involve the efferent branches, as previously explained. A short reflex is completely peripheral and only involves the local integration of sensory input with motor output (Figure 15.8).	B: peripheral.
The urea cycle, a set of biochemical reactions that produces urea from ammonium ions to prevent toxicity, occurs to some extent in the kidney, but primarily in what organ? Here are the choices: A. liver B. skin C. spleen D. colon	Urea Cycle The urea cycle is a set of biochemical reactions that produces urea from ammonium ions in order to prevent a toxic level of ammonium in the body. It occurs primarily in the liver and, to a lesser extent, in the kidney. Prior to the urea cycle, ammonium ions are produced from the breakdown of amino acids. In these reactions, an amine group, or ammonium ion, from the amino acid is exchanged with a keto group on another molecule. This transamination event creates a molecule that is necessary for the Krebs cycle and an ammonium ion that enters into the urea cycle to be eliminated. In the urea cycle, ammonium is combined with CO2, resulting in urea and water. The urea is eliminated through the kidneys in the urine (Figure 24.18).	A: liver.
Cellular respiration is the reverse or opposite of what? Here are the choices: A. spermatogenesis B. photosynthesis C. glycolysis D. reproduction	Specifically, during cellular respiration, the energy stored in glucose is transferred to ATP ( Figure below ). ATP , or adenosine triphosphate, is chemical energy the cell can use. It is the molecule that provides energy for your cells to perform work, such as moving your muscles as you walk down the street. But cellular respiration is slightly more complicated than just converting the energy from glucose into ATP. Cellular respiration can be described as the reverse or opposite of photosynthesis. During cellular respiration, glucose, in the presence of oxygen, is converted into carbon dioxide and water. Recall that carbon dioxide and water are the starting products of photosynthesis. What are the products of photosynthesis?.	B: photosynthesis.
What force pulls object downwards to the earth? Here are the choices: A. momentum B. gravity C. motion D. kinetic energy	Gravity near the Earth pulls an object downwards toward the surface of the Earth with an acceleration of . In the absence of air resistance, all objects will fall with the same acceleration. The letter is used as the symbol for the acceleration of gravity. When talking about an object's acceleration, whether it is due to gravity or not, the acceleration of gravity is sometimes used as a unit of measurement where . So an object accelerating at 2g's is accelerating at or.	B: gravity.
How does deeper material cause convection in the mantle? Here are the choices: A. rises then sinks B. folds C. remains stable D. sinks then rises	Not long after Wegener's death, scientists recognized that there is convection in the mantle. Deeper material is hotter and so it rises. Near the surface, it becomes cooler and denser so it sinks. This creates a convection cell in the mantle.	A: rises then sinks.
From what did the first proto-oncogenes arise? Here are the choices: A. bacteria B. carcinogens C. spores D. viral infections		D: viral infections.
What material used for helium-filled balloons is dense, strong and opaque, with a high molecular mass that forms films that have many fewer pores than rubber? Here are the choices: A. fiberglass B. cellophane C. mylar D. foil	times faster than air. For this reason, high-quality helium-filled balloons are usually made of Mylar, a dense, strong, opaque material with a high molecular mass that forms films that have many fewer pores than rubber. Mylar balloons can retain their helium for days.	C: mylar.
What do erythrocytes carry and deliver to tissues in the body? Here are the choices: A. oxide B. oxygen C. carbon D. Helium	The cell found in greatest abundance in blood is the erythrocyte. Erythrocytes are counted in millions in a blood sample: the average number of red blood cells in primates is 4.7 to 5.5 million cells per microliter. Erythrocytes are consistently the same size in a species, but vary in size between species. For example, the average diameter of a primate red blood cell is 7.5 µl, a dog is close at 7.0 µl, but a cat’s RBC diameter is 5.9 µl. Sheep erythrocytes are even smaller at 4.6 µl. Mammalian erythrocytes lose their nuclei and mitochondria when they are released from the bone marrow where they are made. Fish, amphibian, and avian red blood cells maintain their nuclei and mitochondria throughout the cell’s life. The principal job of an erythrocyte is to carry and deliver oxygen to the tissues. Leukocytes are the predominant white blood cells found in the peripheral blood. Leukocytes are counted in the thousands in the blood with measurements expressed as ranges: primate counts range from 4,800 to 10,800 cells per µl, dogs from 5,600 to 19,200 cells per µl, cats from 8,000 to 25,000 cells per µl, cattle from 4,000 to 12,000 cells per µl, and pigs from 11,000 to 22,000 cells per µl. Lymphocytes function primarily in the immune response to foreign antigens or material. Different types of lymphocytes make antibodies tailored to the foreign antigens and control the production of those antibodies. Neutrophils are phagocytic cells and they participate in one of the early lines of defense against microbial invaders, aiding in the removal of bacteria that has entered the body. Another leukocyte that is found in the peripheral blood is the monocyte. Monocytes give rise to.	B: oxygen.
How many neutrons do 99% of carbon atoms have? Here are the choices: A. sixteen B. five C. eight D. six	All the atoms of a given element have the same number of protons and electrons. The number of neutrons, however, may vary for atoms of the same element. For example, almost 99 percent of carbon atoms have six neutrons, but the rest have either seven or eight neutrons. Atoms of an element that differ in their numbers of neutrons are called isotopes. The nuclei of these isotopes of carbon are shown in the Figure below . The isotope called carbon-14 is used to find the ages of fossils. You can learn how at this URL: http://science. howstuffworks. com/environmental/earth/geology/carbon-14. htm .	D: six.
What are the two metals within a battery called? Here are the choices: A. anode and diode B. anode and sheath C. anode and a cathode D. sheath and a cathode	These values suggest that water should be oxidized at the anode because a smaller potential would be needed—using reaction (ii) for the oxidation would give a less-negative cell potential. When the experiment is run, it turns out chlorine, not oxygen, is produced at the anode. The unexpected process is so common in electrochemistry that it has been given the name overpotential. The overpotential is the difference between the theoretical cell voltage and the actual voltage that is necessary to cause electrolysis. It turns out that the overpotential for oxygen is rather high and effectively makes the reduction potential more positive. As a result, under normal conditions, chlorine gas is what actually forms at the anode. Now consider the cathode. Three reductions could occur:.	C: anode and a cathode.
What is one thing that can not happen to energy? Here are the choices: A. it cannot decrease B. it cannot stay the same C. it cannot increase D. it can not be destroyed	If energy cannot be destroyed, what happens to the energy that is absorbed in an endothermic reaction? The energy is stored in the chemical bonds of the products. This form of energy is called chemical energy. In an endothermic reaction, the products have more stored chemical energy than the reactants. In an exothermic reaction, the opposite is true. The products have less stored chemical energy than the reactants. The excess energy in the reactants is released to the surroundings when the reaction occurs. The graphs in Figure below show the chemical energy of reactants and products in each type of reaction.	D: it can not be destroyed.
Where do most biochemical reactions take place? Here are the choices: A. within cells B. outside of cells C. upper atmosphere D. stomach	Most biochemical reactions take place within cells. Cells are the microscopic building blocks of organisms.	A: within cells.
The ends of linear chromosomes are maintained by the action of which enzyme? Here are the choices: A. cytokine B. insulin C. pepsin D. telomerase	Figure 9.11 The ends of linear chromosomes are maintained by the action of the telomerase enzyme.	D: telomerase.
Through which process does water from the oceans enter the atmosphere? Here are the choices: A. absorption B. perspiration C. evaporation D. oxidation		C: evaporation.
In what type of process does heat flow into its surroundings and cause an increase in kinetic energy? Here are the choices: A. biochemical process B. oscillating process C. chemical process D. exothermic process	In general, the process of interest is taking place in the system, and there are no changes in the composition of the surroundings. However, the temperature of the surroundings does generally change. Entropy changes in the surroundings are determined primarily by the flow of heat into or out of the system. In an exothermic process, heat flows into the surroundings, increasing the kinetic energy of the nearby particles. For an exothermic reaction, ΔS surr is positive. Conversely, heat flows from the surroundings into the system during an endothermic process, lowering the kinetic energy available to the surroundings and resulting in a negative value for ΔS surr .	D: exothermic process.
Prokaryotic organisms, like bacteria, reproduce through what process, where they grow and divide in half? Here are the choices: A. singular fission B. symbiotic fission C. multiple fission D. binary fission	Prokaryotic organisms, like bacteria. Bacteria reproduce through binary fission , where they grow and divide in half ( Figure below ). First, their chromosome replicates and the cell enlarges. The cell then divides into two cells as new membranes form to separate the two cells. After cell division, the two new cells each have one identical chromosome. This simple process allows bacteria to reproduce very rapidly.	D: binary fission.
Displacement is a vector quantity, which means it has both direction and what else? Here are the choices: A. rate B. radiation C. waves D. magnitude	What is the difference between distance and displacement? Whereas displacement is defined by both direction and magnitude, distance is defined only by magnitude. Displacement is an example of a vector quantity. Distance is an example of a scalar quantity. A vector is any quantity with both magnitude and direction. Other examples of vectors include a velocity of 90 km/h east and a force of 500 newtons straight down. The direction of a vector in one-dimensional motion is given simply by a plus.	D: magnitude.
Waste leaves the body in the form of what? Here are the choices: A. feces B. saliva C. impurities D. stomach acid		A: feces.
What process can occur when atoms are exposed to high levels of radiation or when atoms transfer electrons to or from other atoms? Here are the choices: A. oxidation B. ionization C. diffusion D. fusion	The process in which an atom becomes an ion is called ionization. It may occur when atoms are exposed to high levels of radiation or when atoms transfer electrons to or from other atoms.	B: ionization.
Who should an obese person with an eating disorder seek for help? Here are the choices: A. social worker B. health professional C. body builder D. psychiatrist	Some people who are obese have an eating disorder. Eating disorders are mental illnesses that require treatment by health professionals.	B: health professional.
The period of life between the start of puberty and the beginning of adulthood is called? Here are the choices: A. youth B. prenatal C. old age D. adolescence	Adolescence is the period of life between the start of puberty and the beginning of adulthood. Adolescence includes the physical changes of puberty. It also includes many other changes, including significant mental, emotional, and social changes. During adolescence:.	D: adolescence.
What element once commonly used in paint and gasoline has now been found to have dangerous effects? Here are the choices: A. chromium B. plastic C. niacin D. lead	lead: An element that was once commonly used in gasoline and paint, is now found to have dangerous effects, such as brain damage. Lead contamination has many harmful effects on the body.	D: lead.
What can happen spontaneously or as a result of mutagens in the environment? Here are the choices: A. mutations B. lesions C. combustion D. traits	Many mutations are not caused by errors in replication. Mutations can happen spontaneously, and they can be caused by mutagens in the environment. Some chemicals, such as those found in tobacco smoke, can be mutagens. Sometimes mutagens can also cause cancer. Tobacco smoke, for example, is often linked to lung cancer.	A: mutations.
Abnormally high activity or low activity of the parathyroid gland can cause disorders related to levels of what bone mineral? Here are the choices: A. potassium B. collagen C. calcium D. magnesium	Abnormally high activity of the parathyroid gland can cause hyperparathyroidism, a disorder caused by an overproduction of PTH that results in excessive calcium reabsorption from bone. Hyperparathyroidism can significantly decrease bone density, leading to spontaneous fractures or deformities. As blood calcium levels rise, cell membrane permeability to sodium is decreased, and the responsiveness of the nervous system is reduced. At the same time, calcium deposits may collect in the body’s tissues and organs, impairing their functioning. In contrast, abnormally low blood calcium levels may be caused by parathyroid hormone deficiency, called hypoparathyroidism, which may develop following injury or surgery involving the thyroid gland. Low blood calcium.	C: calcium.
Unlike other tetrapod vertebrates (reptiles, birds, and mammals), amphibians do not produce what type of eggs? Here are the choices: A. epithelial B. amniotic C. prokaryotic D. umbilical	Unlike other tetrapod vertebrates (reptiles, birds, and mammals), amphibians do not produce amniotic eggs. Therefore, they must lay their eggs in water so they won’t dry out. Their eggs are usually covered in a jelly-like substance, like the frog eggs shown in Figure below . The jelly helps keep the eggs moist and offers some protection from predators.	B: amniotic.
What is the name for an underground layer of rock that is saturated with groundwater? Here are the choices: A. aqueous cavity B. artesian well C. gradient D. aquifer	An underground layer of rock that is saturated with groundwater is called an aquifer . A diagram of an aquifer is pictured below ( Figure below ). Aquifers are generally found in porous rock, such as sandstone. Water infiltrates the aquifer from the surface. The water that enters the aquifer is called recharge .	D: aquifer.
What are prepared by the oxidation of secondary alcohols? Here are the choices: A. ions B. ketones C. protons D. more alcohol	The carbonyl group, a carbon-to-oxygen double bond, is the defining feature ofaldehydes and ketones. In aldehydes at least one bond on the carbonyl group is a carbon-to-hydrogen bond; in ketones, both available bonds on the carbonyl carbon atom are carbon-to-carbon bonds. Aldehydes are synthesized by the oxidation of primary alcohols. The aldehyde can be further oxidized to a carboxylic acid. Ketones are prepared by the oxidation of secondary alcohols. Mild oxidizing agents oxidize aldehydes to carboxylic acids. Ketones are not oxidized by these reagents. A thiol is a compound with an SH functional group.	B: ketones.
Saturated and unsaturated are the two main kinds of what? Here are the choices: A. acids B. polymers C. fats D. sugars	There are two main types of fats, saturated and unsaturated.	C: fats.
Most reptiles lay what kind of eggs? Here are the choices: A. amniotic B. roe C. umbilical D. hard-shelled	All reptiles have a cloaca , a single exit and entrance for sperm, eggs, and waste, located at the base of the tail. Most reptiles lay amniotic eggs covered with leathery or hard shell. These eggs can be placed anywhere as they don't have to be in a moist environment, like the eggs of amphibians. However, not all species lay eggs, as certain species of squamates can give birth to live young.	A: amniotic.
Sulfur can combine with oxygen to produce what? Here are the choices: A. sulfur dioxide B. sulfur trioxide C. sulfur oxide D. sulfur bioxide	When nonmetals react with one another, the product is a molecular compound. Often, the nonmetal reactants can combine in different ratios and produce different products. Sulfur can also combine with oxygen to produce sulfur trioxide.	B: sulfur trioxide.
The nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by what? Here are the choices: A. viruses B. algae C. pollen D. bacteria	The Nitrogen Cycle Getting nitrogen into the living world is difficult. Plants and phytoplankton are not equipped to incorporate nitrogen from the atmosphere (which exists as tightly bonded, triple covalent N2) even though this molecule comprises approximately 78 percent of the atmosphere. Nitrogen enters the living world via free-living and symbiotic bacteria, which incorporate nitrogen into their macromolecules through nitrogen fixation (conversion of N2). Cyanobacteria live in most aquatic ecosystems where sunlight is present; they play a key role in nitrogen fixation. Cyanobacteria are able to use inorganic sources of nitrogen to “fix” nitrogen. Rhizobium bacteria live symbiotically in the root nodules of legumes (such as peas, beans, and peanuts) and provide them with the organic nitrogen they need. Free-living bacteria, such as Azotobacter, are also important nitrogen fixers. Organic nitrogen is especially important to the study of ecosystem dynamics since many ecosystem processes, such as primary production and decomposition, are limited by the available supply of nitrogen. As shown in Figure 46.17, the nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by bacteria. This process occurs in three steps in terrestrial systems: ammonification, nitrification, and denitrification. First, the ammonification process converts nitrogenous waste from living animals or from the remains of dead animals.	D: bacteria.
What term describes the amount of solute in a given amount of solution? Here are the choices: A. density B. concentration C. cloudiness D. temperature	The concentration of a solution is the amount of solute in a given amount of solution. A dilute solution has a low concentration of solute. A concentrated solution has a high concentration of solute.	B: concentration.
Which process helps absorptive protists absorb food molecules across their cell membranes? Here are the choices: A. metabolism B. activation C. secretion D. diffusion	Absorptive protists absorb food molecules across their cell membranes. This occurs by diffusion. These protists are important decomposers.	D: diffusion.
When matter recycles and changes state what does it gain or lose by doing so? Here are the choices: A. density B. fuel C. energy D. volume	Matter can exist in one of several different states, including a gas, liquid, or solid state. States of matter differ in the amount of energy their molecules have. When matter recycles, it changes state by gaining or losing energy.	C: energy.
Where does oxygen enter the blood? Here are the choices: A. in the liver B. in the heart C. in the veins D. in the lungs		D: in the lungs.
What kind of compounds change color when bases come into contact with them, so they can be used to detect bases? Here are the choices: A. liquid B. metals C. indicators D. parameters	Certain compounds, called indicators, change color when bases come into contact with them, so they can be used to detect bases. An example of an indicator is a compound called litmus. It is placed on small strips of paper that may be red or blue. If you place a few drops of a base on a strip of red litmus paper, the paper will turn blue. You can see this in the Figure below . Litmus isn’t the only detector of bases. Red cabbage juice can also detect bases, as you can see in this video: http://www. youtube. com/watch?v=vrOUdoS2BtQ .	C: indicators.
Concentric circles that spread out through the water around the droplets are actually types of what moving through the water? Here are the choices: A. waves B. lines C. winds D. troughs	No doubt you’ve seen this happen. Droplets of water fall into a body of water, and concentric circles spread out through the water around the droplets. The concentric circles are waves moving through the water.	A: waves.
The smallest units of matter that retain the unique properties of an element are known as what? Here are the choices: A. neutrons B. molecules C. atoms D. protons	All matter is made of tiny particles. Protons, neutrons, and electrons form atoms that bond together to create molecules. Atoms are the smallest units that have the properties of an element. Molecules are the smallest units of a compound. Chemical bonds hold molecules together. Molecules form the different types of minerals. The silicates make up most of Earth's crust. Minerals come together to create the three major rock types. They are igneous, sedimentary, and metamorphic. Igneous rocks form from cooled magma. Sedimentary rocks form from compacted or cemented sediments. Metamorphic rocks are those that have been altered by heat and pressure. These three rock types are the material part of the rock cycle. They are connected by different processes. Different processes convert any type of rock into any other type of rock. These processes are weathering and erosion, crystallization, and burial and pressure, among others. Each rock contains a story of how it formed. For most rocks it is possible to know what it formed from.	C: atoms.
What is a process that changes some chemical substances into other chemical substances? Here are the choices: A. cellular respiration B. spontaneous mutation C. a chemical reaction D. a bio reaction	A chemical reaction is a process that changes some chemical substances into other chemical substances. The substances that start a chemical reaction are called reactants . The substances that form as a result of a chemical reaction are called products . During the reaction, the reactants are used up to create the products. For example, when methane burns in oxygen, it releases carbon dioxide and water. In this reaction, the reactants are methane (CH 4 ) and oxygen (O 2 ), and the products are carbon dioxide (CO 2 ) and water (H 2 O).	C: a chemical reaction.
What type of lens and mirrors have a negative focal length? Here are the choices: A. diverging B. converging C. subverging D. convexing	The focal length , , of a lens or mirror is the distance from the surface of the lens or mirror to the place where the light is focused. This is called the focal point or focus . For diverging lenses or mirrors, the focal length is negative.	A: diverging.
What is the formation of organs from the germ layers called? Here are the choices: A. synaptogenesis B. biosynthesis C. photosynthesis D. organogenesis	43.7 Organogenesis and Vertebrate Formation Organogenesis is the formation of organs from the germ layers. Each germ layer gives rise to specific tissue types. The first stage is the formation of the neural system in the ectoderm. The mesoderm gives rise to somites and the notochord. Formation of vertebrate axis is another important developmental stage.	D: organogenesis.
What must two nuclei do for fusion to occur? Here are the choices: A. explode B. repel each other C. melt D. collide	Two nuclei must collide for fusion to occur. High temperatures are required to give the nuclei enough kinetic energy to overcome the very strong repulsion resulting from their positive charges. A nuclear reactor consists of the following: 1. A nuclear fuel. A fissionable isotope must be present in large enough quantities to sustain a controlled chain reaction. The radioactive isotope is contained in tubes called fuel rods. A moderator. A moderator slows neutrons produced by nuclear reactions so that they can be absorbed by the fuel and cause additional nuclear reactions. A coolant. The coolant carries heat from the fission reaction to an external boiler and turbine where it is transformed into electricity.	D: collide.
What determines the ability of soil particles to bind many nutrients? Here are the choices: A. surface pulses B. surface charges C. layer charges D. currents charges		B: surface charges.
Enthalpy is a measure of the total energy of what kind of system? Here are the choices: A. planetary B. macroscopic C. hypodermic D. thermodynamic	Reactions can proceed by themselves if they are exergonic or exothermic, that is if they release energy. The associated free energy of the reaction is composed of two different thermodynamic quantities, enthalpy and entropy. Enthalpy is a measure of the total energy of a thermodynamic system. The change in enthalpy is positive in endothermic reactions, and negative in exothermic processes.	D: thermodynamic.
In eukaryotes, the new mrna is not yet ready for translation. it must go through more processing before it leaves where? Here are the choices: A. Electrons B. molecules C. nucleus D. protons	In eukaryotes, the new mRNA is not yet ready for translation. It must go through more processing before it leaves the nucleus. This may include splicing, editing, and polyadenylation. These processes modify the mRNA in various ways. Such modifications allow a single gene to be used to make more than one protein.	C: nucleus.
What term describes the splitting of the nucleus of an atom into two smaller nuclei? Here are the choices: A. atomic reaction B. critical fission C. nuclean fusion D. nuclear fission	Nuclear fission is the splitting of the nucleus of an atom into two smaller nuclei. This type of reaction releases a great deal of energy from a very small amount of matter. It begins when the nucleus of a radioactive atom gains a neutron.	D: nuclear fission.
What type of contamination causes almost 90% of diarrheal disease worldwide? Here are the choices: A. air contamination B. water supply contamination C. ground contamination D. food contamination	Unsafe water supplies have drastic effects on human health. Waterborne diseases are diseases due to microscopic pathogens in fresh water. These diseases can be caused by protozoa, viruses, bacteria, and intestinal parasites. In many parts of the world there are no water treatment plants. If sewage or animal manure gets into a river, then people downstream will get sick when they drink the water. According to the World Health Organization (WHO), diarrheal disease is responsible for the deaths of 1.8 million people every year. It was estimated that 88% of the cases of diarrheal disease are caused by unsafe water supplies.	B: water supply contamination.
Why is respiratory acidosis considered to be problematic? Here are the choices: A. excess co2 in blood B. excess oxygen in blood C. causes suffocation D. causes acid stomach	Metabolic acidosis is problematic, as lower-than-normal amounts of bicarbonate are present in the blood. The pCO2 would be normal at first, but if compensation has occurred, it would decrease as the body reestablishes the proper ratio of bicarbonate and carbonic acid/CO2. Respiratory acidosis is problematic, as excess CO2 is present in the blood. Bicarbonate levels would be normal at first, but if compensation has occurred, they would increase in an attempt to reestablish the proper ratio of bicarbonate and carbonic acid/CO2. Alkalosis is characterized by a higher-than-normal pH. Metabolic alkalosis is problematic, as elevated pH and excess bicarbonate are present. The pCO2 would again be normal at first, but if compensation has occurred, it would increase as the body attempts to reestablish the proper ratios of bicarbonate and carbonic acid/CO 2. Respiratory alkalosis is problematic, as CO2 deficiency is present in the bloodstream. The bicarbonate concentration would be normal at first. When renal compensation occurs, however, the bicarbonate concentration in blood decreases as the kidneys attempt to reestablish the proper ratios of bicarbonate and carbonic acid/CO2 by eliminating more bicarbonate to bring the pH into the physiological range.	A: excess co2 in blood.
When light strikes rhodopsin, the g-protein transducin is activated, which in turn activates what? Here are the choices: A. hydrolysis B. photosynthesis C. phosphodiesterase D. aldosterone	Figure 36.20 When light strikes rhodopsin, the G-protein transducin is activated, which in turn activates phosphodiesterase. Phosphodiesterase converts cGMP to GMP, thereby closing sodium channels. As a result, the membrane becomes hyperpolarized. The hyperpolarized membrane does not release glutamate to the bipolar cell.	C: phosphodiesterase.
In what stage of photosynthesis does the calvin cycle occur? Here are the choices: A. third B. fourth C. first D. second	The Calvin cycle occurs in the second stage of photosynthesis. This stage takes place in the stroma of the chloroplast. In the Calvin cycle, carbon dioxide is used to produce glucose (sugar) using the energy stored in ATP and NADPH. The energy is released from these molecules when ATP loses phosphate (P i ) to become ADP and NADPH loses hydrogen (H) to become NADP + .	D: second.
All of the planets rotate on their axes in the same direction that they move around the sun, except for which one? Here are the choices: A. Jupiter B. venus C. uranus D. Saturn	All of the planets rotate on their axes in the same direction that they move around the Sun. Except for Uranus. Uranus is tilted on its side. Its axis is almost parallel to its orbit. So Uranus rolls along like a bowling ball as it revolves around the Sun. How did Uranus get this way? Scientists think that the planet was struck and knocked over by another planet-sized object. This collision probably took place billions of years ago.	C: uranus.
What is the process by which organisms change in small ways over time? Here are the choices: A. microevolution B. natural selection C. spontaneous mutation D. adaptation	Microevolution is the process by which organisms change in small ways over time.	A: microevolution.
What regulates the cell cycle only when they are tightly bound to cdks? Here are the choices: A. cyclins B. kinases C. subclades D. hormones	Cyclins regulate the cell cycle only when they are tightly bound to Cdks. To be fully active, the Cdk/cyclin complex must also be phosphorylated in specific locations. Like all kinases, Cdks are enzymes (kinases) that phosphorylate other proteins. Phosphorylation activates the protein by changing its shape. The proteins phosphorylated by Cdks are involved in advancing the cell to the next phase. (Figure 10.12). The levels of Cdk proteins are relatively stable throughout the cell cycle; however, the concentrations of cyclin fluctuate and determine when Cdk/cyclin complexes form. The different cyclins and Cdks bind at specific points in the cell cycle and thus regulate different checkpoints.	A: cyclins.

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.