In a population of giraffes, an environmental change occurs that favors individuals that are tallest. As a result, more of the taller individuals are able to obtain nutrients and survive to pass along their genetic information. This is an example of<n>A.directional selection.<n>B.stabilizing selection.<n>C.sexual selection.<n>D.disruptive selection.[SEP]A
Which of the changes below following the start codon in an mRNA would most likely have the greatest deleterious effect?<n>A.a deletion of a single nucleotide<n>B.a deletion of a nucleotide triplet<n>C.a single nucleotide substitution of the nucleotide occupying the first codon position<n>D.a single nucleotide substitution of the nucleotide occupying the third codon position[SEP]A
The energy given up by electrons as they move through the electron transport chain is used to<n>A.break down glucose<n>B.make glucose<n>C.produce ATP<n>D.make NADH[SEP]C
During the period when life is believed to have begun, the atmosphere on primitive Earth contained abundant amounts of all the following gases EXCEPT<n>A.oxygen<n>B.hydrogen<n>C.ammonia<n>D.methane[SEP]A
Convergent evolution is best exemplified by which of the following?<n>A.The pectoral fins of fish and the front legs of cats<n>B.The presence of a notochord in all chordate embryos<n>C.The wings of an insect and the wings of a bird<n>D.The leaves of an oak tree and the spines of a cactus[SEP]C
Which of the following would most likely provide examples of mitotic cell divisions?<n>A.cross section of muscle tissue<n>B.cross section of an anther (site of pollen production in a flower)<n>C.longitudinal section of a shoot tip<n>D.cross section of a leaf[SEP]C
Invertebrate immune systems possess which of the following?<n>A.Cytotoxic T-lymphocytes<n>B.Phagocytes<n>C.B-cells<n>D.Helper T-cells[SEP]B
Two unrelated species evolve in a way that makes them more similar.<n>A.Divergent evolution<n>B.Convergent evolution<n>C.Parallel evolution<n>D.Coevolution[SEP]B
Which of the following is the most likely benefit of periodic natural wildfires in some forest ecosystems?<n>A.The fires remove dead and decaying plant matter, reducing the risk of more intense and destructive fires.<n>B.The fires leach nutrients from the soil‚ preventing the germination of plants that might compete with native species.<n>C.The fires drive off herbivores whose plant-based diets reduce the amount of vegetation.<n>D.The fires dry out the soil and decrease the chance of flooding after heavy rains.[SEP]A
In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (i.e., they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following should least likely be observed in the algae-eater population over the course of many generations?<n>A.Selection for drab coloration of the algae-eaters<n>B.Selection for nocturnal algae-eaters (active only at night)<n>C.Selection for larger female algae-eaters, bearing broods composed of more, and larger, young<n>D.Selection for algae-eaters that become sexually mature at smaller overall body sizes[SEP]C
A man contracts the same flu strain for the second time in a single winter season. The second time he experiences fewer symptoms and recovers more quickly. Which cells are responsible for this rapid recovery?<n>A.Helper T cells<n>B.Cytotoxic T cells<n>C.Memory cells<n>D.Plasma cells[SEP]C
The same gene that causes various coat patterns in wild and domesticated cats also causes the cross-eyed condition in these cats, the cross-eyed condition being slightly maladaptive. In a hypothetical environment, the coat pattern that is associated with crossed eyes is highly adaptive, with the result that both the coat pattern and the cross-eyed condition increase in a feline population over time. Which statement is supported by these observations?<n>A.Evolution is progressive and tends toward a more perfect population.<n>B.Phenotype is often the result of compromise.<n>C.Natural selection reduces the frequency of maladaptive genes in populations over the course of time.<n>D.Polygenic inheritance is generally maladaptive, and should become less common in future generations.[SEP]B
Which of the following statements is correct?<n>A.Water flows from hypertonic to hypotonic.<n>B.Germinating seeds use less oxygen than do nongerminating seeds.<n>C.The rate of transpiration decreases with an increase in air movement.<n>D.Smaller DNA fragments migrate more rapidly than do larger DNA fragments on gel electrophoresis.[SEP]D
A gas phase is generally absent from which of the following biogeochemical cycles?<n>A.Water<n>B.Carbon<n>C.Sulfur<n>D.Phosphorus[SEP]D
Which of the following is a property that is shared by Zika fever‚ West Nile fever‚ and malaria?<n>A.The diseases are caused by viruses.<n>B.The diseases occur only in individuals who visit or live in tropical countries.<n>C.The pathogens that cause the diseases have developed resistance to antibiotics.<n>D.The pathogens that cause the diseases are primarily transmitted by the bite of an infected mosquito.[SEP]D
If the HMS Beagle had completely bypassed the Galapagos Islands, Darwin would have had a much poorer understanding of the<n>A.relative stability of a well-adapted population's numbers over many generations.<n>B.ability of populations to undergo modification as they adapt to a particular environment.<n>C.tendency of organisms to produce the exact number of offspring that the environment can support.<n>D.unlimited resources that support population growth in most natural environments.[SEP]B
Which of the following statements about lipids is correct?<n>A.Unsaturated fatty acids are linked to heart disease.<n>B.Lipids make up most cell surface receptors.<n>C.Phospholipids are water soluble.<n>D.Steroids are lipids that consist of glycerol and fatty acids.[SEP]C
All of the following are examples of connective tissue EXCEPT<n>A.ligaments<n>B.muscle<n>C.blood<n>D.cartilage[SEP]B
The light reactions of photosynthesis supply the Calvin cycle with which of the following?<n>A.The light reactions provide oxygen for the light-independent reactions.<n>B.ATP and NADPH provide the power and raw materials for the Calvin cycle.<n>C.Water entering the plant through the roots provides hydrogen directly to the Calvin cycle.<n>D.CO2 released by the light-dependent reactions provides the raw material for the Calvin cycle.[SEP]B
When the first tiny prokaryotic cell took up residence inside a larger prokaryotic cell, it heralded the advent of the eukaryotic cell and led to an explosion of new life on Earth. Since then, most cells on Earth have internal organelles. Which of the following best summarizes an advantage of having internal membranes and organelles?<n>A.DNA can reproduce more efficiently.<n>B.Even though prokaryotes do not have mitochondria, they contain structures that carry out the same function.<n>C.Organelles separate specific reactions in the cell and increase metabolic efficiency.<n>D.Compartmentalization enables prokaryotes to reproduce more quickly.[SEP]C
Which of the following is correct about vaccination?<n>A.It increases the number of different receptors that recognize a particular pathogen.<n>B.It increases the number of different macrophages specific to the antigen.<n>C.It increases the number of epitopes that the immune system can recognize.<n>D.It increases the number of lymphocytes with receptors that can recognize and bind to the antigen.[SEP]D
The calypso orchid, Calypso bulbosa, grows in close association with mycorrhizae fungi. The fungi penetrate the roots of the flower and take advantage of the plant's food resources. The fungi concentrate rare minerals, such as phosphates, in the roots and make them readily accessible to the orchid. This situation is an example of<n>A.parasitism<n>B.commensalism<n>C.mutualism<n>D.endosymbiosis[SEP]C
Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful meiosis. Consequently, which statement about mules is true?<n>A.They have a relative evolutionary fitness of zero.<n>B.Their offspring have less genetic variation than the parents.<n>C.Mutations cannot occur in their genomes.<n>D.If crossing-over happens in mules, then it must be limited to prophase of mitosis.[SEP]A
ADH is a hormone secreted by the kidneys that reduces the amount of water excreted in the urine. ADH is released in times of dehydration. This is an example of<n>A.innate behavior.<n>B.maintaining homeostasis.<n>C.failure to respond to the environment.<n>D.positive feedback.[SEP]B
All of the following statements are true EXCEPT<n>A.thyroxine increases the rate of metabolism<n>B.insulin decreases storage of glycogen<n>C.vasopressin stimulates water reabsorption in the kidney<n>D.epinephrine increases blood sugar levels and heart rate[SEP]B
Which of the following statements best describes what a Barr body is and its significance?<n>A.It is an inactivated Y chromosome and results in a man being sterile.<n>B.It is an inactivated Y chromosome, and the person who has it appears female.<n>C.It is an inactivated X chromosome and results in females with half their cells having one X inactivated and the other half of their cells having the other X inactivated.<n>D.It is an inactivated X chromosome and results in females who are sterile.[SEP]C
A heterotroph<n>A.obtains its energy from sunlight, harnessed by pigments<n>B.obtains its energy by oxidizing organic molecules<n>C.makes organic molecules from CO2<n>D.obtains its energy by consuming exclusively autotrophs[SEP]B
Which of the following reactions occurs in the forward direction during glycolysis but in the reverse direction during fermentation?<n>A.pyruvate → lactate<n>B.pyruvate → ethanol<n>C.NAD+ + H+ + 2e- → NADH<n>D.ADP + P → ATP[SEP]C
A researcher grows a population of ferns in her laboratory. She notices, after a few generations, a new variant that has a distinct phenotype. When she tries to breed the original phenotype with the new one, no offspring are produced. When she breeds the new variants, however, offspring that look like the new variant result. What originally caused the change in the variant?<n>A.Karyotyping<n>B.Balance polymorphism<n>C.Mutation<n>D.Polyploidy[SEP]C
Which of the following statements most accurately explains what EcoR1 is?<n>A.It is a bacterium that lives in the human large intestine.<n>B.It is the best-studied bacteriophage, a virus that attacks E. coli.<n>C.It is a restriction enzyme extracted from E. coli.<n>D.It is a type of DNA used extensively in research.[SEP]C
Which of the following pairs of structures is least likely to represent homology?<n>A.The wings of a bat and the arms of a human<n>B.The hemoglobin of a baboon and that of a gorilla<n>C.The mitochondria of a plant and those of an animal<n>D.The wings of a bird and those of an insect[SEP]D
The development of an egg without fertilization is known as<n>A.meiosis<n>B.parthenogenesis<n>C.embryogenesis<n>D.vegetative propagation[SEP]B
In minks, the gene for brown fur (B) is dominant over the gene for silver fur (b). Which set of genotypes represents a cross that could produce offspring with silver fur from parents that both have brown fur?<n>A.BB BB<n>B.BB Bb<n>C.Bb Bb<n>D.Bb bb[SEP]C
Male satin bowerbirds adorn structures that they build, called "bowers," with parrot feathers, flowers, and other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed, allow males to mate with them. The evolution of this male behavior is due to<n>A.frequency-dependent selection.<n>B.artificial selection.<n>C.sexual selection.<n>D.natural selection.[SEP]C
Which of the following best explains why a population is described as the evolutionary unit?<n>A.Genetic changes can only occur at the population level.<n>B.The gene pool in a population remains fixed over time.<n>C.Natural selection affects individuals, not populations.<n>D.Individuals cannot evolve, but populations can.[SEP]D
If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be<n>A.23%<n>B.46%<n>C.54%<n>D.92%[SEP]C
Which of these is a statement that Darwin would have rejected?<n>A.Environmental change plays a role in evolution.<n>B.The smallest entity that can evolve is an individual organism.<n>C.Individuals can acquire new characteristics as they respond to new environments or situations.<n>D.Inherited variation in a population is a necessary precondition for natural selection to operate.[SEP]B
Which of the following contributes the MOST to genetic variability in a population?<n>A.Sporulation<n>B.Binary fission<n>C.Vegetative propagation<n>D.Mutation[SEP]D
Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ?<n>A.The appendix can be surgically removed with no immediate ill effects.<n>B.The appendix might have been larger in fossil hominids.<n>C.The appendix has a substantial amount of defensive lymphatic tissue.<n>D.Individuals with a larger-than-average appendix leave fewer offspring than those with a below-average-sized appendix.[SEP]C
According to the heterotroph hypothesis, which event had to occur before oxygen filled the atmosphere?<n>A.Heterotrophs had to remove carbon dioxide from the air.<n>B.Autotrophs, which make their own food, had to evolve.<n>C.Heterotrophs had to evolve.<n>D.Autotrophs had to convert atmospheric nitrogen to nitrate.[SEP]B
Two related species evolve in a way that makes them less similar.<n>A.Divergent evolution<n>B.Convergent evolution<n>C.Parallel evolution<n>D.Coevolution[SEP]A
Which of the following statements best summarizes evolution as it is viewed today?<n>A.It is goal-directed.<n>B.It represents the result of selection for acquired characteristics.<n>C.It is synonymous with the process of gene flow.<n>D.It is the differential survival and reproduction of the most-fit phenotypes.[SEP]D
Mosquitoes resistant to the pesticide DDT first appeared in India in 1959 within 15 years of widespread spraying of the insecticide. Which of the following statement best explains how the resistant mosquitoes arose?<n>A.Some mosquitoes experienced a mutation after being exposed to DDT that made them resistant to the insecticide. Then their population expanded because these moquitoes had no competition.<n>B.Some mosquitoes were already resistant to DDT when DDT was first sprayed. Then their population expanded because all the susceptible mosquitoes had been exterminated.<n>C.DDT is generally a very effective insecticide. One can only conclude that it was manufactured improperly.<n>D.Although DDT is effective against a wide range of insects, it is not effective against mosquitoes.[SEP]B
DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that<n>A.humans and chimpanzees share a relatively recent common ancestor.<n>B.humans evolved from chimpanzees.<n>C.chimpanzees evolved from humans.<n>D.convergent evolution led to the DNA similarities.[SEP]A
Yeast cells carry out both aerobic and anaerobic respiration. A yeast cell that is fed on glucose is moved from an aerobic to an anaerobic environment. Which of the following statements is correct and gives the correct reason for it?<n>A.The cell dies because it cannot make ATP.<n>B.The cell would need to consume glucose at a much greater rate because aerobic respiration is much more efficient as compared with anaerobic respiration.<n>C.The cell would need to consume another food source other than glucose because it will not be able to make adequate ATP with only glucose.<n>D.The cell will begin to divide rapidly because larger cells require more oxygen and glucose than smaller ones.[SEP]B
A researcher conducts a survey of a biome and finds 35 percent more species than she has found in any other biome. Which biome is she most likely to be in?<n>A.Tundra<n>B.Tiaga<n>C.Tropical rainforest<n>D.Temperate deciduous forest[SEP]C
Which statement about variation is true?<n>A.All phenotypic variation is the result of genotypic variation.<n>B.All genetic variation produces phenotypic variation.<n>C.All nucleotide variability results in neutral variation.<n>D.All new alleles are the result of nucleotide variability.[SEP]D
Which of the following best explains why people can digest starch but cannot digest cellulose even though both molecules are composed of glucose monomers?<n>A.The bonds linking the monomers of starch differ in shape from the bonds linking the monomers of cellulose.<n>B.Molecules of starch are much smaller than molecules of cellulose.<n>C.Starch is an intracellular molecule, while cellulose is an extracellular molecule.<n>D.Starch is hydrated by water, but cellulose is not.[SEP]A
In humans, fertilization normally occurs in the<n>A.ovary<n>B.fallopian tube<n>C.uterus<n>D.placenta[SEP]B
Which of the following is a biotic factor that could affect the growth rate of a population?<n>A.Volcanic eruption<n>B.Glacier melting<n>C.Destruction of the ozone layer<n>D.Sudden reduction in the animal food resource[SEP]C
As a young biologist, Charles Darwin had expected the living plants of temperate South America would resemble those of temperate Europe, but he was surprised to find that they more closely resembled the plants of tropical South America. The biological explanation for this observation is most properly associated with the field of<n>A.meteorology.<n>B.embryology.<n>C.vertebrate anatomy.<n>D.biogeography.[SEP]D
It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that<n>A.0<n>B.common environments are inhabited by the same organisms.<n>C.the islands were originally part of the continent.<n>D.the island forms and mainland forms are converging.[SEP]A
The Krebs cycle in humans occurs in the<n>A.mitochondrial matrix<n>B.inner mitochondrial membrane<n>C.outer mitochondrial membrane<n>D.intermembrane space[SEP]A
Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are<n>A.homologous.<n>B.examples of convergent evolution.<n>C.adaptations to a common environment.<n>D.B and C only[SEP]D
During which phase of the cell cycle does the quantity of DNA in a eukaryotic cell typically double?<n>A.G_1<n>B.G_2<n>C.M<n>D.S[SEP]D
Two trees of the same species growing close together will use the same resources, such as light, water, and nutrients. If any of these resources becomes limiting, then each tree will receive less of it than if the trees were growing farther apart. This scenario is an example of which of the following?<n>A.Parasitism<n>B.Commensalism<n>C.Natural selection<n>D.Intraspecific competition[SEP]D
Short sequence by promoter that assists transcription by interacting with regulatory proteins.<n>A.Enhancer<n>B.Repressor<n>C.Operator<n>D.Promoter[SEP]C
Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvier's attempt to explain the existence of<n>A.evolution.<n>B.the fossil record.<n>C.uniformitarianism.<n>D.the origin of new species.[SEP]B
Hydrangea flowers have one gene for flower color. Plants of the same genetic variety have flowers that range in color from blue to pink with the color varying due to the type of soil in which they are grown. Which of the following statement best explains this phenomenon?<n>A.The alleles for flower color show incomplete dominance where neither trait is dominant; expression of the genes shows a blending of traits.<n>B.The alleles for flower color are codominant; both traits show depending on the environment.<n>C.In this case, the environment alters the expression of a trait.<n>D.The genes for flower color show polygenic inheritance.[SEP]C
When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of<n>A.sexual selection.<n>B.disruptive selection.<n>C.balancing selection.<n>D.frequency-dependent selection.[SEP]D
Although mutations occur at a regular and predictable rate, which of the following statements is the LEAST likely reason the frequency of mutation appears to be low?<n>A.Some mutations produce alleles that are recessive and may not be expressed.<n>B.Some undesirable phenotypic traits may be prevented from reproducing.<n>C.Some mutations cause such drastic phenotypic changes that they are removed from the gene pool.<n>D.The predictable rate of mutation results in ongoing variability in a gene pool.[SEP]D
Crossover would most likely occur in which situation?<n>A.Two genes (1 and 2) are located right next to each other on chromosome A.<n>B.Gene 1 is located on chromosome A, and gene 2 is on chromosome B.<n>C.Genes 1 and 2 are located near each other on the X chromosome.<n>D.Gene 1 is located on chromosome A; gene 2 is located far away but on the same chromosome.[SEP]D
Which aspects of cell structure best reveals the unity of all life?<n>A.All cells are surrounded by a plasma membrane.<n>B.All cells have at least one nucleus.<n>C.All cells carry out cellular respiration in mitochondria.<n>D.The surface-to-volume ratio of all cells is the same.[SEP]A
This biome contains plants whose roots cannot go deep due to the presence of a permafrost.<n>A.Desert<n>B.Tundra<n>C.Taiga<n>D.Deciduous forests[SEP]C
This biome contains trees that drop their leaves during the winter months.<n>A.Desert<n>B.Tundra<n>C.Taiga<n>D.Deciduous forests[SEP]D
A change in a neuron membrane potential from +50 millivolts to -70 millivolts is considered<n>A.depolarization<n>B.repolarization<n>C.hyperpolarization<n>D.an action potential[SEP]B
All of the following play a role in morphogenesis EXCEPT<n>A.apoptosis<n>B.homeotic genes<n>C.operons<n>D.inductive effects[SEP]C
Most animal cells, regardless of species, are relatively small and about the same size. Relative to larger cells, why is this?<n>A.Smaller cells avoid excessive osmosis and subsequent lysis.<n>B.Smaller cells have a smaller surface-to-volume ratio.<n>C.Smaller cells have a larger surface-to-volume ratio.<n>D.Smaller cells fit together more tightly.[SEP]C
Which of the following is (are) required when performing a polymerase chain reaction (P C R) on a DNA sample?<n>A.Reverse transcriptase<n>B.A vacuum chamber<n>C.Primers complementary to certain portions of the DNA<n>D.DNA ligase[SEP]C
Each of the following has a better chance of influencing gene frequencies in small populations than in large populations, but which one most consistently requires a small population as a precondition for its occurrence?<n>A.Mutation<n>B.Non-random mating<n>C.Genetic drift<n>D.Natural selection[SEP]C
No two people are genetically identical, except for identical twins. The chief cause of genetic variation among human individuals is<n>A.new mutations that occurred in the preceding generation.<n>B.the reshuffling of alleles in sexual reproduction.<n>C.genetic drift due to the small size of the population.<n>D.geographic variation within the population.[SEP]B
Two genes (B and E) determine coat color in Labrador retrievers. Alleles B and b code for how much melanin is present. The dominant allele B codes for black fur, the recessive allele b codes for brown hair. A second gene consisting of two alleles, E and e, codes for the deposition of pigment in the hair. In this case, the alleles for pigment deposition (E or e) are said to be epistatic to the gene that codes for black or brown pigment. If the dominant allele (E) is not present, regardless of the genotype at the black/brown locus, the animal's fur will be yellow.<n>A.BBEe will be brown.<n>B.BbEe will be brown.<n>C.Bbee will be brown.<n>D.BBee will be yellow.[SEP]D
Which of the following statements is NOT correct about ancient Earth?<n>A.Earth was formed about 4? billion years ago.<n>B.Amino acid synthesis could have been stimulated by volcanic eruption.<n>C.The first cells formed about 3? billion years ago, according to the fossil record.<n>D.The presence of free oxygen facilitated the rapid formation of organic molecules.[SEP]D
In modern terminology, diversity is understood to be a result of genetic variation. Sources of variation for evolution include all of the following except<n>A.mistakes in translation of structural genes.<n>B.mistakes in DNA replication.<n>C.translocations and mistakes in meiosis.<n>D.recombination at fertilization.[SEP]A
DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run?<n>A.Larger doses of DDT should have been applied.<n>B.All habitats should have received applications of DDT at about the same time.<n>C.The frequency of DDT application should have been higher.<n>D.None of the individual insects should have possessed genomes that made them resistant to DDT.[SEP]D
Within a few weeks of treatment with the drug 3TC, a patient's HIV population consists entirely of 3TC-resistant viruses. How can this result best be explained?<n>A.HIV can change its surface proteins and resist vaccines.<n>B.The patient must have become reinfected with 3TC-resistant viruses.<n>C.HIV began making drug-resistant versions of reverse transcriptase in response to the drug.<n>D.A few drug-resistant viruses were present at the start of treatment, and natural selection increased their frequency.[SEP]D
The higher the proportion of loci that are "fixed" in a population, the lower is that population's<n>A.nucleotide variability.<n>B.genetic polyploidy.<n>C.average heterozygosity.<n>D.A and C only[SEP]D
The resting membrane potential depends on which of the following? I. Active transport II. Selective permeability III. Differential distribution of ions across the axonal membrane<n>A.III only<n>B.I and II only<n>C.II and III only<n>D.I, II, and III[SEP]D
Which of the following statements about the light-dependent reactions of photosynthesis is correct?<n>A.They provide the carbon that becomes incorporated into sugar.<n>B.They produce PGA, which is converted to glucose by carbon fixation in the light-independent reactions.<n>C.Water is split apart, providing hydrogen ions and electrons to NADP for temporary storage.<n>D.They occur in the stroma of chloroplasts.[SEP]C
When we say that an individual organism has a greater fitness than another individual, we specifically mean that the organism<n>A.lives longer than others of its species.<n>B.competes for resources more successfully than others of its species.<n>C.mates more frequently than others of its species.<n>D.leaves more viable offspring than others of its species.[SEP]D
Most Swiss starlings produce four to five eggs in each clutch. Those producing fewer or more than this have reduced fitness. Which of the following terms best describes this?<n>A.artificial selection<n>B.directional selection<n>C.stabilizing selection<n>D.disruptive selection[SEP]C
Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?<n>A.The two species live at great distance from each other.<n>B.The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.<n>C.The sizes of the structures in adult members of both species are similar in size.<n>D.Both species are well adapted to their particular environments.[SEP]B
When driving from east to west in the U.S. from a forest ecosystem to grasslands, trees gradually give way to grasses. Which of the following is the critical factor responsible for this shift?<n>A.Amount of sunlight<n>B.Availability of oxygen<n>C.Availability of water<n>D.Length of growing season[SEP]C
Within a cell, the amount of protein synthesized using a given mRNA molecule depends in part on which of the following?<n>A.DNA methylation suppresses the expression of genes.<n>B.Transcription factors mediate the binding of RNA polymerase and the initiation of transcription, which will determine how much protein is manufactured.<n>C.The speed with which mRNA is degraded will determine how much protein is synthesized.<n>D.The location and number of ribosomes in a cell will solely determine how much protein is synthesized.[SEP]C
All of the following are modes of asexual reproduction EXCEPT<n>A.sporulation<n>B.fission<n>C.budding<n>D.meiosis[SEP]D
A rooster with gray feathers and a hen with the same phenotype produce 17 gray, 7 black, and 8 white chicks. What is the simplest explanation for the inheritance of these colors in chickens?<n>A.The trait for gray is epistatic over the trait for black.<n>B.The trait for gray is epistatic over the trait for white.<n>C.The traits for black and white color demonstrate incomplete dominance.<n>D.The traits for black and white color demonstrate codominance.[SEP]C
Which of the following statements about cellular respiration is correct?<n>A.Most CO2 produced during cellular respiration is released from glycolysis.<n>B.Protons are pumped through ATP synthase by active transport.<n>C.The final electron acceptor of the electron transport chain is NAD+.<n>D.ATP is formed because an endergonic reaction is coupled with an exergonic reaction.[SEP]D
Which of the following principles is NOT part of Darwin's theory of evolution by natural selection?<n>A.Evolution is a gradual process that occurs over a long period of time.<n>B.Every population has tremendous variation.<n>C.Mutations are the main source of all variation in a population.<n>D.Organisms will overpopulate area, giving rise to competition.[SEP]C
In Darwin's thinking, the more closely related two different organisms are, the<n>A.more similar their habitats are.<n>B.less similar their DNA sequences are.<n>C.more recently they shared a common ancestor.<n>D.less likely they are to have the same genes in common.[SEP]C
Which of the following is most likely to increase the rate of diffusion of an uncharged solute across the plasma membrane of a cell?<n>A.Decreasing the number of different solutes in the solution that bathes the cells<n>B.Increasing the concentration gradient of the solute across the membrane<n>C.Increasing the ratio of phospholipids to proteins in the membrane<n>D.Decreasing the membrane potential across the membrane[SEP]B
In a certain pond, there are long-finned fish and short-finned fish. A horrific summer thunderstorm leads to the death of a disproportionate number of long-finned fish to the point where the relative frequency of the two forms has drastically shifted. This is an example of<n>A.gene flow.<n>B.natural selection.<n>C.genetic drift.<n>D.stabilizing selection.[SEP]C
A form of species interaction in which one of the species benefits while the other is unaffected is called<n>A.parasitism.<n>B.mutualism.<n>C.commensalism.<n>D.symbiosis.[SEP]C
Chemical substances released by organisms that elicit a physiological or behavioral response in other members of the same species are known as<n>A.auxins<n>B.hormones<n>C.pheromones<n>D.enzymes[SEP]C
In reference to a segment of DNA, which of the following molecules contains the fewest number of nucleotides?<n>A.a single strand of the original DNA segment<n>B.a single strand of the original DNA segment after a point mutation<n>C.the primary RNA transcript (before splicing) from the original DNA<n>D.a single strand of complementary DNA (cDNA) made from the original DNA[SEP]D
All viruses contain at least these two principal components:<n>A.DNA and proteins<n>B.nucleic acid and a capsid<n>C.DNA and cell membrane<n>D.RNA and cell wall[SEP]B
Imagine an organism whose 2n = 96. Meiosis would leave this organism’s cells with how many chromosomes?<n>A.192<n>B.96<n>C.48<n>D.24[SEP]C
Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?<n>A.All species are fixed in the form in which they are created.<n>B.Populations tend to increase at a faster rate than their food supply normally allows.<n>C.Earth changed over the years through a series of catastrophic upheavals.<n>D.The environment is responsible for natural selection.[SEP]B
Which of the following would most likely describe the fate of a vesicle formed as a result of phagocytosis?<n>A.The vesicle merges with a mitochondrion.<n>B.The vesicle merges with a lysosome.<n>C.The vesicle is shuttled to the nucleus, and its contents become part of the nucleolus.<n>D.The vesicle releases its contents to the cytoplasm to be digested.[SEP]B
A population undergoes a shift in which those who are really tall and those who are really short decrease in relative frequency compared to those of medium size, due to a change in the availability of resources. This is an example of<n>A.directional selection.<n>B.stabilizing selection.<n>C.disruptive selection.<n>D.sympatric speciation.[SEP]B
Which of the following theories is based on the notion that mitochondria and chloroplasts evolved from prokaryotic cells?<n>A.Fluid mosaic model<n>B.Endosymbiotic model<n>C.Taxonomic model<n>D.Respiration feedback model[SEP]B
The nucleotide sequence of a DNA molecule is 5′-C-A-T-3′. A mRNA molecule with a complementary codon is transcribed from the DNA in the process of protein synthesis a tRNA pairs with a mRNA codon. What is the nucleotide sequence of the tRNA anticodon?<n>A.5′-G-T-A-3′<n>B.5′-G-U-A-3′<n>C.5′-C-A-U-3′<n>D.5-′U-A-C-3′[SEP]C
During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?<n>A.Small birds gaining larger beaks by exercising their mouth parts.<n>B.Small birds mutating their beak genes with the result that later-generation offspring have larger beaks.<n>C.Small birds anticipating the long drought and eating more to gain weight and, consequently, growing larger beaks.<n>D.More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.[SEP]D
Which of the following is NOT a characteristic of asexual reproduction in animals?<n>A.Daughter cells have the same number of chromosomes as the parent cell.<n>B.Daughter cells are identical to the parent cell.<n>C.The parent cell produces diploid cells.<n>D.The daughter cells fuse to form a zygote.[SEP]D
A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true?<n>A.The amount of available food may have increased.<n>B.The number of predators may have decreased.<n>C.The squirrels of subsequent generations should show greater levels of genetic variation than previous generations, because squirrels that would not have survived in the past will now survive.<n>D.A, B, and C[SEP]D
Which group is composed entirely of individuals who maintained that species are fixed (i.e., unchanging)?<n>A.Aristotle, Cuvier, and Lamarck<n>B.Linnaeus, Cuvier, and Lamarck<n>C.Lyell, Linnaeus, and Lamarck<n>D.Aristotle, Linnaeus, and Cuvier[SEP]D
Except for identical twins, no two people are genetically identical. Which of the following statements most accurately describes the main source of variation in humans?<n>A.The main source of variation in humans is genetic drift.<n>B.Changes in the environment cause rapid changes in different human populations.<n>C.Shuffling of alleles is responsible for the greatest variation in humans.<n>D.Mutations are responsible for the greatest changes in different human populations.[SEP]C
An eager AP Biology student interested in studying osmosis and the movement of water in solutions took a dialysis bag containing a 0.5 M solution and placed it into a beaker containing a 0.6 M solution. If this bag were instead placed into a beaker of distilled water, what would be the expected result?<n>A.There will be a net flow of water out of the bag, causing it to decrease in size.<n>B.There will be a net flow of water into the bag, causing it to swell in size.<n>C.The bag will remain the exact same size because no water will move at all.<n>D.The solute will flow out of the dialysis bag into the beaker.[SEP]B
Crossing-over during meiosis permits scientists to determine<n>A.the chance for variation in zygotes<n>B.the rate of mutations<n>C.the distance between genes on a chromosome<n>D.which traits are dominant or recessive[SEP]C
An organism exposed to wild temperature fluctuations shows very little, if any, change in its metabolic rate. This organism is most probably a<n>A.ectotherm.<n>B.endotherm.<n>C.thermophyle.<n>D.ascospore.[SEP]B
What was the prevailing notion prior to the time of Lyell and Darwin?<n>A.Earth is a few thousand years old, and populations are unchanging.<n>B.Earth is a few thousand years old, and populations gradually change.<n>C.Earth is millions of years old, and populations rapidly change.<n>D.Earth is millions of years old, and populations are unchanging.[SEP]A
On Andros Islands in the Bahamas, populations of mosquito fish, Gambusia hubbsi, colonized a series of ponds. These ponds are no longer connected. However, the environments are very similar except that some ponds contain predatory fish, while others do not. In high predation ponds, selection has favored the evolution of a body shape that enables rapid bursts of speed. In low predation ponds, another body type is favored—one that is well-suited to swim for long periods of time.<n>A.Reproductive isolation caused geographic isolation.<n>B.Reproductive isolation was not complete.<n>C.Allopatric isolation brought about reproductive isolation.<n>D.Sympatric isolation brought about reproductive isolation.[SEP]C
Which of the following statement is supported by the information given in the pedigree?<n>A.The P generation mother is X-X.<n>B.The P generation father is X-Y.<n>C.If parents 1 and 2 in row II have another child, the chance that the child would be afflicted with alkaptonuria is 25%.<n>D.The genotype of woman 1 is X-X.[SEP]C
A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. That the actual forelimbs of these mammals do not seem to be optimally arranged is because<n>A.natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time.<n>B.natural selection operates in ways that are beyond the capability of the human mind to comprehend.<n>C.in many cases, phenotype is not merely determined by genotype, but by the environment as well.<n>D.natural selection is generally limited to modifying structures that were present in previous generations and in previous species.[SEP]D
Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?<n>A.All organisms require energy.<n>B.All organisms use essentially the same genetic code.<n>C.All organisms reproduce.<n>D.All organisms show heritable variation.[SEP]B
Organisms in which of the following phyla have a true coelom?<n>A.Platyhelminthes<n>B.Porifera<n>C.Annelida<n>D.Nematoda[SEP]B
A certain autosomal recessive trait is expressed in 1% of a population. Assuming that the population is in Hardy-Weinberg equilibrium, what percent of the population are carriers but do not express the trait?<n>A.10%<n>B.18%<n>C.27%<n>D.50%[SEP]B
Which of the following properties is responsible for holding together the water molecules in a vertical column of water in xylem vessels of a plant?<n>A.the strong adhesion property of water<n>B.the strong cohesion of property of water<n>C.the high heat capacity of water<n>D.the strong cohesion property of cellulose in the xylem cell wall[SEP]B
Which of the following statements is NOT correct about apoptosis?<n>A.Apoptosis, a special type of cell division, requires multiple cell signaling.<n>B.The fact that apoptosis is widespread across several kingdoms is evidence that it evolved early in the evolution of eukaryotes.<n>C.Apoptosis plays a crucial role in the development of fingers in embryonic development.<n>D.Apoptosis prevents an aging and dying cell from damaging neighboring cells.[SEP]A
All of the following organs in the digestive system secrete digestive enzymes EXCEPT the<n>A.mouth<n>B.stomach<n>C.gall bladder<n>D.small intestine[SEP]C
All of the following are stimulated by the sympathetic nervous system EXCEPT<n>A.dilation of the pupil of the eye<n>B.constriction of blood vessels<n>C.increased secretion of the sweat glands<n>D.increased peristalsis in the gastrointestinal tract[SEP]D
In the inherited disorder called Pompe disease, glycogen breakdown in the cytosol occurs normally and blood glucose levels are normal, yet glycogen accumulates in lysosomes. This suggests a malfunction with<n>A.enzymes in the lysosomes<n>B.enzymes in the mitochondria<n>C.membrane transport during exocytosis<n>D.membrane transport during endocytosis[SEP]A
A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of<n>A.a cline.<n>B.a bottleneck.<n>C.relative fitness.<n>D.genetic drift.[SEP]A
Which of the following is an example of a cline?<n>A.The hybrid tomato plant is stronger and produces better fruit than the pure genotype.<n>B.There are two distinct varieties in one population of snail that inhabits an island in the Pacific Ocean.<n>C.Males of some species have long antlers to fight other males for females.<n>D.In one species of rabbit, the ones that evolved in the cold, snowy north are white, while the ones that evolved in the south are brown.[SEP]D
A healthy man and woman are worried about having children because they are both carriers of sickle-cell disease. If the couple have a biological child, what is the chance that the child will inherit sickle-cell disease?<n>A.100%<n>B.75%<n>C.50%<n>D.25%[SEP]D
Females with Turner's syndrome have a high incidence of hemophilia, a recessive, X-linked trait. Based on this information, it can be inferred that females with this condition<n>A.have an extra X chromosome<n>B.have an extra Y chromosome<n>C.lack an X chromosome<n>D.have red blood cells that clump[SEP]C
Which of the following is the direct energy source that allows ATP synthase to produce ATP in mitochondria?<n>A.NADH diffusing from the mitochondrial intermembrane space to the matrix<n>B.The reduction of NAD+ during the conversion of pyruvate to acetyl-CoA<n>C.H+ ions flowing down a gradient across the mitochondrial inner membrane<n>D.The energy of electrons passing along the electron transport chain[SEP]C
Which of the following cells is most closely associated with phagocytosis?<n>A.Neutrophils<n>B.Plasma cells<n>C.B cells<n>D.Memory cells[SEP]A
Lampreys attach to the skin of lake trout and absorb nutrients from its body. This relationship is an example of<n>A.commensalism<n>B.parasitism<n>C.mutualism<n>D.gravitropism[SEP]B
Which of the following is correct about organisms that are the first to colonize a habitat undergoing ecological succession?<n>A.They are the fiercest competitors in the area.<n>B.They maintain the habitat as it is for their own kind.<n>C.They change the habitat in a way that makes it more habitable for other organisms.<n>D.They are small invertebrates.[SEP]C
Unlike large populations, small populations are vulnerable to various processes that draw populations down an extinction vortex toward smaller and smaller populations until no individuals survive. Which of the following statements correctly identifies the factors that endanger a population?<n>A.Inbreeding and loss of genetic variation threaten a population.<n>B.Migration of new individuals into the population threatens a population.<n>C.Mutation reduces the health of a population.<n>D.Breeding with individuals from a different population may cause the extinction of the first population due to a decrease in diversity.[SEP]A
Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the following terms best describes this?<n>A.artificial selection<n>B.directional selection<n>C.stabilizing selection<n>D.disruptive selection[SEP]B
Which describes an African butterfly species that exists in two strikingly different color patterns?<n>A.artificial selection<n>B.directional selection<n>C.stabilizing selection<n>D.disruptive selection[SEP]D
Regarding meiosis and mitosis, one difference between the two forms of cellular reproduction is that in meiosis<n>A.there is one round of cell division, whereas in mitosis there are two rounds of cell division<n>B.separation of sister chromatids occurs during the second division, whereas in mitosis separation of sister chromatids occurs during the first division<n>C.chromosomes are replicated during interphase, whereas in mitosis chromosomes are replicated during prophase<n>D.spindle fibers form during prophase, whereas in mitosis the spindle fibers form during metaphase[SEP]B
Which of the following about meiosis is NOT true?<n>A.Meiosis produces two haploid gametes.<n>B.Homologous chromosomes join during synapsis.<n>C.Sister chromatids separate during meiosis I.<n>D.Crossing-over increases genetic variation in gametes.[SEP]C
Oligomycin is an antibiotic that blocks proton channels in the cristae of mitochondria by binding to ATP synthase. Which of the following would be the first expected response after the application of oligomycin to cells?<n>A.Water production would increase.<n>B.H+ would increase inside the intermembrane space (the compartment between inner and outer membranes).<n>C.H+ would increase in the matrix (inside mitochondrial inner membrane).<n>D.H+ would increase outside mitochondria.[SEP]B
If neutral variation is truly "neutral," then it should have no effect on<n>A.nucleotide diversity.<n>B.average heterozygosity.<n>C.our ability to measure the rate of evolution.<n>D.relative fitness.[SEP]D
Which of the following characteristics would allow you to distinguish a prokaryotic cell from an animal cell?<n>A.Ribosomes<n>B.Cell membrane<n>C.Chloroplasts<n>D.Cell wall[SEP]D
This process leads to the net production of two pyruvate, two ATP, and two NADH.<n>A.Glycolysis<n>B.Chemiosmosis<n>C.Fermentation<n>D.Calvin cycle[SEP]A
When oxygen becomes unavailable, this process regenerates NAD+, allowing respiration to continue.<n>A.Glycolysis<n>B.Chemiosmosis<n>C.Fermentation<n>D.Calvin cycle[SEP]C
Before the human genome was sequenced by the Human Genome Project, scientists expected that they would find about 100,000 genes. In fact, they discovered that humans have only about 24,000 genes. How can we exhibit so many different traits from so few genes?<n>A.Modification of histone proteins usually increases the function of genes.<n>B.Epigenetics enables one gene to produce many different traits.<n>C.This is proof that pseudogenes and introns are expressed.<n>D.A single gene can produce more than one trait because of alternative splicing[SEP]D
Which of the following must exist in a population before natural selection can act upon that population?<n>A.Genetic variation among individuals<n>B.Variation among individuals caused by environmental factors<n>C.Sexual reproduction<n>D.B and C only[SEP]A
You observe a species that gives birth to only one offspring at a time and has a relatively long life-span for its body size. Which of the following is probably also true of this organism?<n>A.It lives in a newly colonized habitat.<n>B.It is an aquatic organism.<n>C.It requires relatively high parental care of offspring.<n>D.The age at which the offspring themselves can give birth is relatively young.[SEP]C
A piece of potato is dropped into a beaker of pure water. Which of the following describes the initial condition when the potato enters the water?<n>A.The water potential of the pure water is negative.<n>B.The water potential of the pure water is positive.<n>C.The water potential of the potato is positive.<n>D.The water potential of the potato is negative.[SEP]D
In most ecosystems, net primary productivity is important because it represents the<n>A.energy available to producers<n>B.total solar energy converted to chemical energy by producers<n>C.biomass of all producers<n>D.energy available to heterotrophs[SEP]D
During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?<n>A.Characteristics acquired during an organism's life are generally not passed on through genes.<n>B.Spontaneous mutations can result in the appearance of new traits.<n>C.Only favorable adaptations have survival value.<n>D.Disuse of an organ may lead to its eventual disappearance.[SEP]A
Incomplete dominance and epistasis are two terms that define genetic relationships. Which of the following statements best describes the differences or similarities between the two terms?<n>A.Both terms describe inheritance controlled by the interaction of multiple alleles at different loci.<n>B.Both terms describe inheritance controlled by the interaction of multiple genes at different loci.<n>C.Incomplete dominance describes the interaction of two genes at different loci; epistasis describes the interaction of two alleles.<n>D.Incomplete dominance describes the interaction of two alleles on one gene; epistasis describes the interaction of two genes and their respective alleles.[SEP]D
Which of the following statements about the DNA in one of your liver cells is correct?<n>A.Your liver cells contain the same DNA as your white blood cells.<n>B.Most of the DNA in your liver cells will be transcribed but not translated.<n>C.Most of the DNA in your liver cells will be transcribed in the nucleus and translated in the cytoplasm.<n>D.DNA in your liver cells contains genes unique to storing glycogen, while other cells do not contain those genes.[SEP]A
Energy is harvested during cellular respiration in stages. Which of the following correctly states which phase of cellular respiration harvests the most energy and the correct explanation why?<n>A.The most energy is released during the Krebs cycle because it is here that pyruvate is completely broken down into CO2.<n>B.The most energy is released during the Krebs cycle because in addition to the production of ATP, both FADH2 and NADH are produced. Each of those molecules will release 2 ATPs and 3 ATPs, respectively.<n>C.The most energy is released during oxidative phosphorylation because in addition to the phosphorylation of ADP into ATP, all the potential energy held in NADH and FADH is transferred to ATP.<n>D.The most energy is released during oxidative phosphorylation because H2O is completely broken down into H+ and O2.[SEP]C
Which of the following best explains why drinking breast milk is beneficial to a human infant?<n>A.Breast milk contains vitamins that repair mutations originating in the sperm or egg.<n>B.Breast milk contains maternal antibodies that protect against gastrointestinal pathogens.<n>C.Breast milk contains maternal vaccines that destroy common childhood pathogens.<n>D.Breast milk contains red blood cells with adult hemoglobin that are beneficial to the infant's developing brain.[SEP]B
During oxidative phosphorylation, the energy needed to drive ATP synthesis comes from one source. Which of the following statements states the immediate source of that energy?<n>A.Electrons flow down an electron transport chain as they are attracted to oxygen.<n>B.The transfer of a phosphate group to ADP is exergonic.<n>C.The bonding of electrons to oxygen at the end of the chain releases energy.<n>D.The proton gradient across the membrane where the ATP synthase is embedded represents potential energy.[SEP]D
Easily produced genetic variation is key to the rapid evolution of viral and microbial populations. Furthermore, pathogens that need to escape the immune system rely on this variation to generate new surface antigens that go unrecognized by the host’s immune system. Which of the following is an example of this antigenic variation?<n>A.HIV, which can remain integrated into the host genome for many years<n>B.The flu virus, which changes its envelope proteins<n>C.MRSA, which has become resistant to many antibiotics<n>D.Multiple sclerosis, which attacks the cells of the nervous system[SEP]B
If a couple has had three sons and the woman is pregnant with their fourth child, what is the probability that child 4 will also be male?<n>A.1/2<n>B.1/4<n>C.1/8<n>D.1/16[SEP]A
Which of the following is an incorrect statement about gel electrophoresis?<n>A.DNA migrates from positive charge to negative charge.<n>B.Smaller DNA travels faster.<n>C.The DNA migrates only when the current is running.<n>D.The longer the current is running, the farther the DNA will travel.[SEP]A
Which of the following observations helped Darwin shape his concept of descent with modification?<n>A.Species diversity declines farther from the equator.<n>B.Fewer species live on islands than on the nearest continents.<n>C.Birds can be found on islands located farther from the mainland than the birds' maximum nonstop flight distance.<n>D.South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.[SEP]D
Which of the following statements about post-transcriptional modification are incorrect?<n>A.A poly-A tail is added to the 3′ end of the mRNA.<n>B.A guanine cap is added to the 5′ end of the mRNA.<n>C.Introns are removed from the mRNA.<n>D.Posttranscriptional modification occurs in the cytoplasm.[SEP]D
Photosynthesis requires<n>A.glucose, light, CO2<n>B.light, CO2, water<n>C.water, soil, O2<n>D.O2, water, light[SEP]B
The first simple cells evolved approximately 3.5 billion years ago, followed by the more complex eukaryotic cells 2.1 billion years ago. Which of the following statements is correct?<n>A.Eukaryotic organelles helped create separate environments for metabolic reactions, thus increasing their metabolic efficiency.<n>B.Prokaryotic and eukaryotic cells have no structural similarities.<n>C.The organelles in larger eukaryotic cells took care of the problems of having a larger surface area–to–volume ratio.<n>D.Eukaryotic cells are able to multiply faster based on their more complex structure.[SEP]A
The sequence of amino acids in hemoglobin molecules of humans is more similar to the hemoglobin of chimpanzees than it is to the hemoglobin of dogs. This similarity suggests that<n>A.humans and dogs are more closely related than humans and chimpanzees<n>B.humans and chimpanzees are more closely related than humans and dogs<n>C.humans are related to chimpanzees but not to dogs<n>D.humans and chimpanzees are closely analogous[SEP]B
Basepair sequence that signals the start site for gene transcription.<n>A.Enhancer<n>B.Repressor<n>C.Operator<n>D.Promoter[SEP]D
Those being hunted adopt a coloring scheme that allows them to blend in to the colors of the environment.<n>A.Aposomatic coloration<n>B.Batesian mimicry<n>C.Deceptive markings<n>D.Cryptic coloration[SEP]D
A baby duck runs for cover when a large object is tossed over its head. After this object is repeatedly passed overhead, the duck learns there is no danger and stops running for cover when the same object appears again. This is an example of<n>A.imprinting.<n>B.fixed-action pattern.<n>C.agonistic behavior.<n>D.habituation.[SEP]D
Stretching out from the equator is a wide belt of tropical rain forests that are being cut down to provide exotic woods for export to the U.S. and to make land available to graze beef cattle. Which of the following statements is a negative consequence of clear-cutting the tropical rain forests?<n>A.Indigenous populations will have access to modern conveniences.<n>B.There will be less precipitation in those clear-cut areas.<n>C.U.S. markets will have access to less expensive beef.<n>D.Deforestation will allow more sunlight to penetrate areas that were kept dark by dense vegetation.[SEP]B
The theory of evolution is most accurately described as<n>A.an educated guess about how species originate.<n>B.one possible explanation, among several scientific alternatives, about how species have come into existence.<n>C.an opinion that some scientists hold about how living things change over time.<n>D.an overarching explanation, supported by much evidence, for how populations change over time.[SEP]D
Which of the following statements explains how a point mutation can have no negative impact in the protein formed from a sequence in DNA?<n>A.The first codon of a gene is always AUG, a leader sequence; a mutation in that sequence will have no effect on the protein produced.<n>B.Several codons code for the same amino acid.<n>C.DNA polymerase and DNA ligase carry out excision repair before transcription.<n>D.RNA processing will repair point mutations before mRNA leaves the nucleus.[SEP]B
Which of the following statements correctly characterizes an autoimmune disease?<n>A.T cells attack healthy body cells.<n>B.An aneurysm is a weakness in the wall of a blood vessel that causes it to balloon out. The vessel can rupture and cause a hemorrhage.<n>C.Several factors cause hypertension: smoking, being overweight, lack of physical activity, and too much salt in the diet.<n>D.Alzheimer's disease is caused by the buildup of plaque within the brain, causing brain cells to die.[SEP]A
All of the following play an important role in regulating respiration in humans EXCEPT<n>A.an increase in the amount of CO2 in the blood<n>B.a decrease in the amount of O2 in the blood<n>C.a decrease in the plasma pH level<n>D.strenuous exercise[SEP]B
Water and minerals that reach the xylem in the center of a plant root must first<n>A.move through neighboring phloem vessels<n>B.cross open stomata in the root epidermis<n>C.cross the endodermis of the root cortex<n>D.pass through the pith of the root cap[SEP]C
A lizard lacking a chemical defense mechanism that is colored in the same way as a lizard that has a defense mechanism is displaying<n>A.aposometric coloration.<n>B.cryptic coloration.<n>C.Batesian mimicry.<n>D.Müllerian mimicry.[SEP]C
Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?<n>A.None of the organisms depicted by the tree ate the same foods.<n>B.Some of the organisms depicted by the tree had lived in different habitats.<n>C.The skeletal remains of the organisms depicted by the tree were incomplete (i.e., some bones were missing).<n>D.Relationships between DNA sequences among the species did not match relationships between skeletal patterns.[SEP]D
Sexual dimorphism is most often a result of<n>A.pansexual selection.<n>B.stabilizing selection.<n>C.intrasexual selection.<n>D.intersexual selection.[SEP]D
Which of the following statements about meiosis is correct?<n>A.The daughter cells are genetically identical to the parent cells.<n>B.Homologues pair during prophase II.<n>C.DNA replication occurs before meiosis I and meiosis II.<n>D.The number of chromosomes is reduced.[SEP]D
Stomata allow gases, such as H2O and CO2, to exchange between the inside of a plant leaf and the surrounding environment. Which of the following occurs under normal daytime environmental conditions?<n>A.H2O diffuses out of the leaf faster than CO2 enters.<n>B.H2O diffuses out of the leaf slower than CO2 enters.<n>C.CO2 diffuses out of the leaf faster than H2O enters.<n>D.H2O exchanges with CO2 at equal rates.[SEP]A
Which of these makes determining the evolutionary relatedness of different species based on the amino acid sequence of homologous proteins generally less accurate than determinations of relatedness based on the nucleotide sequences of homologous genes?<n>A.Silent mutations<n>B.Gene duplications<n>C.Translocation events that change gene sequences<n>D.Crossing-over[SEP]A
An animal that is harmless copies the appearance of an animal that is dangerous as a defense mechanism to make predators think twice about attacking.<n>A.Aposomatic coloration<n>B.Batesian mimicry<n>C.Deceptive markings<n>D.Cryptic coloration[SEP]B
The pH of two lakes is measured. Lake A has a pH of 8.0; Lake B has a pH of 6.0. Which of the following statements is correct about these lakes?<n>A.Lake B is alkaline.<n>B.Lake B is 100 times more alkaline than Lake A.<n>C.The hydrogen ion concentration of Lake B is 104 M.<n>D.The pH of both lakes will decrease in response to acid rain.[SEP]D
A plant grows in the opposite direction of the gravitational force. This is an example of<n>A.positive thignotropism<n>B.negative phototropism<n>C.positive phototropism<n>D.negative gravitropism[SEP]D
Which of the following is known to be involved in the photoperiodic flowering response of angiosperms?<n>A.Auxin<n>B.Cytochrome<n>C.Phytochrome<n>D.Gibberellins[SEP]C
In plants, the tendency of climbing vines to twine their tendrils around a trellis is called<n>A.thigmotropism<n>B.hydrotropism<n>C.phototropism<n>D.geotropism[SEP]A
Which of the following is not an observation or inference on which natural selection is based?<n>A.There is heritable variation among individuals.<n>B.Poorly adapted individuals never produce offspring.<n>C.Species produce more offspring than the environment can support.<n>D.Individuals whose characteristics are best suited to the environment generally leave more offspring than those whose characteristics are less suited.[SEP]B
Microtubules are protein filaments assembled from tubulin protein subunits. The chemical colchicine prevents the assembly of microtubules by binding to tubulin protein subunits. Which of the following cellular processes would be most impaired by the application of colchicine?<n>A.the alignment and separation of chromosomes during mitosis<n>B.the coordination of ribosomes and mRNA during protein synthesis<n>C.the movement of substances across the plasma membrane<n>D.the accumulation of protons inside the thylakoids of chloroplasts during chemiosmosis[SEP]A
The principle inorganic compound found in living things is<n>A.carbon<n>B.oxygen<n>C.water<n>D.glucose[SEP]C
Which of the following statements is an inference of natural selection?<n>A.Subsequent generations of a population should have greater proportions of individuals that possess traits better suited for success.<n>B.An individual organism undergoes evolution over the course of its lifetime.<n>C.Habitats do not generally have unlimited resources.<n>D.Natural populations tend to reproduce to their full biological potential.[SEP]A
Recently, seasonal dead zones in low-oxygen waters have been occurring annually in the Gulf of Mexico near the mouth of the Mississippi River. The dead zones result from the rapid growth of photosynthetic phytoplankton (algal blooms) and their subsequent decay by oxygen-depleting microbes in the water column. Which of the following factors most likely triggers the algal blooms and the associated dead zones?<n>A.A decrease in the light level in surface waters as day length starts to shorten after the summer solstice<n>B.Increased predation by marine larvae and other zooplankton during the summer months<n>C.A summer influx of nutrients derived from chemical fertilizers that are high in nitrogen and phosphorus<n>D.Decreased competition from other marine phytoplankton during the summer months[SEP]C
Which of the following best summarizes the process of allopatric speciation?<n>A.differential changes in allele frequencies → reproductive isolation → reproductive barriers → new species<n>B.catastrophic event → reproductive isolation → reproductive barriers → new species<n>C.reproductive isolation → differential changes in allele frequencies → reproductive barriers → new species<n>D.geographic isolation → reproductive isolation → differential changes in allele frequencies → reproductive barriers → new species[SEP]D
In a hypothetical population's gene pool, an autosomal gene, which had previously been fixed, undergoes a mutation that introduces a new allele, one inherited according to incomplete dominance. Natural selection then causes stabilizing selection at this locus. Consequently, what should happen over the course of many generations?<n>A.The proportions of both types of homozygote should decrease.<n>B.The proportion of the population that is heterozygous at this locus should remain constant.<n>C.The population's average heterozygosity should increase.<n>D.Both A and C[SEP]D
Which of the following is the correct characteristic of arteries?<n>A.They are thin-walled blood vessels.<n>B.They contain valves that prevent backflow.<n>C.They always carry oxygenated blood.<n>D.They carry blood away from the heart.[SEP]D
Which of the following statements about trypsin is NOT true?<n>A.It is an organic compound made of proteins.<n>B.It is a catalyst that alters the rate of a reaction.<n>C.It is operative over a wide pH range.<n>D.The rate of catalysis is affected by the concentration of substrate.[SEP]C
Transcription-affecting DNA region that may be located thousands of basepairs away from the promoter.<n>A.Enhancer<n>B.Repressor<n>C.Operator<n>D.Promoter[SEP]A
Which of the following are traits that are affected by more than one gene?<n>A.Heterozygous traits<n>B.Pleiotropic traits<n>C.Polygenic traits<n>D.Blended alleles[SEP]C
A student conducts an experiment to test the efficiency of a certain enzyme. Which of the following protocols would probably not result in a change in the enzyme’s efficiency?<n>A.Bringing the temperature of the experimental setup from 20°C to 50°C<n>B.Adding an acidic solution to the setup<n>C.Adding substrate but not enzyme<n>D.Placing the substrate and enzyme in a container with double the capacity[SEP]D
Kangaroo rats are better able to concentrate urine than humans are. It would be expected that, compared to the nephrons of human kidneys, the nephrons of kangaroo-rat kidneys would have<n>A.thicker walls, which are impermeable to water<n>B.shorter loops of Henle<n>C.longer loops of Henle<n>D.shorter collecting ducts[SEP]C
The geneticist Mary Lyon hypothesized the existence of structures visible just under the nuclear membrane in mammals, which were later named Barr bodies. Which of the following statement is NOT correct about Barr bodies?<n>A.In the early female embryo, one copy of the X chromosome becomes inactivated in every body cell.<n>B.The same chromosome in every cell of a normal female is inactivated.<n>C.A male with the XXY genotype will have one Barr body.<n>D.Barr bodies consist of highly methylated DNA.[SEP]B
An animal cell that is permeable to water but not salts has an internal NaCl concentration of 10%. If placed in freshwater the cell will<n>A.plasmolyze<n>B.swell and eventually lyse<n>C.endocytose water into a large central vacuole<n>D.shrivel[SEP]B
Chemiosmosis occurs in I.Mitochondria II. Nuclei III. Chloroplasts<n>A.I only<n>B.II only<n>C.III only<n>D.I and III[SEP]D
All of the following are examples of events that can prevent interspecific breeding EXCEPT<n>A.the potential mates experience geographic isolation<n>B.the potential mates experience behavioral isolation<n>C.the potential mates have different courtship rituals<n>D.the potential mates have similar breeding seasons[SEP]D
The relatives of a group of pelicans from the same species that separated from each other because of an unsuccessful migration are reunited 150 years later and find that they are unable to produce offspring. This is an example of<n>A.allopatric speciation.<n>B.sympatric speciation.<n>C.genetic drift.<n>D.gene flow.[SEP]A
If two modern organisms are distantly related in an evolutionary sense, then one should expect that<n>A.they live in very different habitats.<n>B.they should share fewer homologous structures than two more closely related organisms.<n>C.their chromosomes should be very similar.<n>D.they shared a common ancestor relatively recently.[SEP]B
When water evaporates from the surface of a pond, what happens to the remaining liquid water?<n>A.The surface water cools.<n>B.The surface water warms.<n>C.The surface water temperature remains unchanged.<n>D.The pH of the remaining water decreases.[SEP]A
Members of which of the following groups are most likely to be surrounded by a protein coat?<n>A.Viruses<n>B.Bacteria<n>C.Eukaryotes<n>D.Archaea[SEP]A
Villi and microvilli are present in the small intestine and aid in reabsorption by<n>A.increasing the surface area of the small intestine<n>B.decreasing the surface area of the small intestine<n>C.making the small intestine more hydrophilic<n>D.making the small intestine more hydrophobic[SEP]A
The transfer of DNA between two bacterial cells connected by sex pili is known as<n>A.specialized transduction.<n>B.conjugation.<n>C.transformation.<n>D.generalized transduction.[SEP]B
More than a dozen species of Darwin's finches with various specialized adaptations inhabit the Galápagos Islands. Each species possesses a specialized adaptation for obtaining food. Why is it that similar adaptations do not exist among the finches of the South American mainland, the presumed origin of the Galápagos finch ancestor?<n>A.The various foods available on the mainland are different than those on the Galápagos Islands.<n>B.South American predators limited evolution of the mainland finch.<n>C.Reproductive isolation is not possible on the mainland.<n>D.The available niches that the Darwin's finches exploited on the Galápagos Islands were already occupied by other species of birds on the mainland.[SEP]D
Which of the events described below agrees with the idea of catastrophism?<n>A.The gradual uplift of the Himalayas by the collision of the Australian crustal plate with the Eurasian crustal plate<n>B.The formation of the Grand Canyon by the Colorado River over millions of years<n>C.The gradual deposition of sediments many kilometers thick on the floors of seas and oceans<n>D.The sudden demise of the dinosaurs, and various other groups, by the impact of a large extraterrestrial body with Earth[SEP]D
Which of the following statements correctly describes what happens to the preRNA during RNA processing?<n>A.Introns are removed in the nucleus. A 5′ cap and the poly-A tail are added after the preRNA leaves the nucleus.<n>B.Introns are removed and both a 5′ cap and a poly-A tail are added before the preRNA leaves the nucleus.<n>C.Exons are removed and a 5′ cap is added before the preRNA leaves the nucleus. After leaving the nucleus, the poly-A tail is added.<n>D.Point mutations are repaired, exons are removed, and both a 5′ cap and a poly-A tail are added before the preRNA leaves the nucleus.[SEP]B
A small population of birds is blown to an isolated island by a hurricane and establishes a colony. The gene pool of the newly established population of birds is likely to reflect the effects of which of the following?<n>A.Directed mutation<n>B.Genetic drift<n>C.Adaptive radiation<n>D.Disruptive selection[SEP]B
Nymphaea odorata, a water lily, is an aquatic plant whose leaves and flowers float on the surface of the water. Which of the following characteristics would be expected for leaves of this plant?<n>A.stomata on the top surface and relatively few water-conducting (xylem) cells<n>B.stomata on the top surface and relatively many water-conducting (xylem) cells<n>C.stomata on the bottom surface and relatively few water-conducting (xylem) cells<n>D.stomata on the bottom surface and relatively many water-conducting (xylem) cells[SEP]A
Which of the following statements is not correct about lipids?<n>A.Lipids consist of fatty acids and glycerol.<n>B.Steroids are examples of lipids.<n>C.The molecules of a saturated fatty acid are packed so close together that they form a solid at room temperature.<n>D.The head of a phospholipid is hydrophobic, and the tails are hydrophilic.[SEP]D
Heterozygote advantage should be most closely linked to which of the following?<n>A.sexual selection<n>B.stabilizing selection<n>C.random selection<n>D.directional selection[SEP]B
African lungfish often live in small, stagnant, freshwater pools. With reduced gills, they differ from other fish in that they breathe air. They also differ in that they release the nitrogen waste urea instead of ammonia. Which of the following statements correctly explains how this is an advantage for lungfish?<n>A.Urea is insoluble in water and sinks to the bottom of the small pools. Thus the poisonous substance is isolated from the fish.<n>B.Ammonia, which is highly toxic, would endanger lungfish that inhabit the small pools.<n>C.Other fish in the small pools can use urea as an energy source.<n>D.The highly toxic urea makes the pool uninhabitable to competitors.[SEP]B
Which of the following statements about the immune system is NOT correct?<n>A.Innate immunity, also known as the adaptive immune response, relies on circulating phagocytes engulfing foreign substances.<n>B.Adaptive immunity is a slower response than innate immunity.<n>C.Innate immunity activates a humoral response.<n>D.Dendritic cells are antigen presenting cells.[SEP]A
Which of the following is most correct concerning cell differentiation in vertebrates?<n>A.Cells in different tissues contain different sets of genes, leading to structural and functional differences.<n>B.Differences in the timing and expression levels of different genes leads to structural and functional differences.<n>C.Differences in the reading frame of mRNA leads to structural and functional differences.<n>D.Differences between tissues result from spontaneous morphogenesis.[SEP]B
All of the following support the endosymbiotic theory that ancestors of mitochondria and chloroplasts were once independent, free-living prokaryotes EXCEPT:<n>A.Mitochondria and chloroplasts divide independently of the eukaryotic host cell by a process similar to binary fission.<n>B.Mitochondria and chloroplasts have ribosomes that more closely resemble those of bacteria than of eukaryotic cells.<n>C.Mitochondria and chloroplasts function independently from the eukaryotic host cell.<n>D.Mitochondria, chloroplasts, and bacteria have a single, circular chromosome without histones or proteins.[SEP]C
The frequency of a particular allele in a population of 1,000 birds in Hardy-Weinberg equilibrium is 0.3. If the population remains in equilibrium, what would be the expected frequency of that allele after 500 years?<n>A.It will increase if the allele is favorable or will decrease if it is unfavorable for individuals in that population.<n>B.Not enough information is provided to determine if the frequency of the allele will remain the same or change.<n>C.The frequency of the allele will remain at 0.3 because the population is at Hardy-Weinberg equilibrium.<n>D.The frequency of the allele will remain the same; this is an example of the bottleneck effect.[SEP]C
Which of the following best accounts for the ability of legumes to grow well in nitrogen-poor soils?<n>A.These plants make their own proteins.<n>B.These plants have a mutualistic relationship with nitrogen-fixing bacteria.<n>C.These plants are capable of directly converting nitrogen gas into nitrates.<n>D.These plants do not require nitrogen to make plant proteins.[SEP]B
To ensure that hatchling sea turtles orient to the sea rather than inland, which of the following is the most environmentally sound practice around sea turtle nest sites?<n>A.Digging troughs in the sand from the nests to the sea<n>B.Minimizing artificial lighting in the area<n>C.Scattering preferred turtle foods between the nests and the sea<n>D.Building low fences on the sand dunes[SEP]B
In general, animal cells differ from plant cells in that animal cells have<n>A.a cell wall made of cellulose<n>B.lysosomes<n>C.large vacuoles that store water<n>D.centrioles within centrosomes[SEP]D
Which of the following disorders will most likely result from X chromosome aneuploidy in women?<n>A.Cystic fibrosis<n>B.Hemophilia<n>C.Turner syndrome<n>D.Tay-Sachs disease[SEP]C
Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?<n>A.Each bird evolved a deeper, stronger beak as the drought persisted.<n>B.Each bird developed a deeper, stronger beak as the drought persisted.<n>C.Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.<n>D.Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.[SEP]C
The normal pH of the cytosol is about 7.2. Most enzymes in the lysosome, however, are only active at a pH of 5. This suggests that<n>A.only acidic substances can undergo enzymatic processing in lysosomes<n>B.most enzymes in the lysosome are incapable of catalyzing substrates inside the lysosome<n>C.enzymes in the lysosome are released to the cytosol<n>D.protons are actively pumped into the lysosome[SEP]D
A feature of amino acids NOT found in carbohydrates is the presence of<n>A.carbon atoms<n>B.oxygen atoms<n>C.nitrogen atoms<n>D.hydrogen atoms[SEP]C
A researcher grows a population of ferns in her laboratory. She notices, after a few generations, a new variant that has a distinct phenotype. When she tries to breed the original phenotype with the new one, no offspring are produced. When she breeds the new variants, however, offspring that look like the new variant result. What kind of speciation does this example illustrate?<n>A.Allopatric<n>B.Sympatric<n>C.Isolated<n>D.Polyploidy[SEP]B
Natural selection is based on all of the following except<n>A.genetic variation exists within populations.<n>B.the best-adapted individuals tend to leave the most offspring.<n>C.individuals who survive longer tend to leave more offspring than those who die young.<n>D.individuals adapt to their environments and, thereby, evolve.[SEP]D
In chick embryos, the extraembryonic membrane that provides nourishment to the fetus is the<n>A.amnion<n>B.chorion<n>C.placenta<n>D.egg yolk[SEP]D
A certain species of land snail exists as either a cream color or a solid brown color. Intermediate individuals are relatively rare. Which of the following terms best describes this?<n>A.artificial selection<n>B.directional selection<n>C.stabilizing selection<n>D.disruptive selection[SEP]D
Once a plasmid has incorporated specific genes, such as the gene coding for the antibiotic ampicillin, into its genome, the plasmid may be cloned by<n>A.inserting it into a virus to generate multiple copies<n>B.treating it with a restriction enzyme in order to cut the molecule into small pieces<n>C.inserting it into a suitable bacterium in order to produce multiple copies<n>D.running it on a gel electrophoresis in order to determine the size of the gene of interest[SEP]C
Which of the following pairs of scientists pioneered the ecological discipline known as island biogeography?<n>A.Robert MacArthur and E. O. Wilson<n>B.James Watson and Francis Crick<n>C.Matthias Schleiden and Theodor Schwann<n>D.Alfred Hershey and Martha Chase[SEP]A
The acrosome and cortical reactions that occur immediately after fertilization ensure which of the following?<n>A.The sperm will fertilize the ovum.<n>B.The zygote will begin to divide normally.<n>C.One and only one sperm will fertilize the egg.<n>D.The zygote will not divide into two embryos, producing twins.[SEP]C
snRNPs are most closely associated with which of the following?<n>A.Cell division<n>B.Apoptosis<n>C.Replication of DNA<n>D.RNA processing[SEP]D
Transpiration is a result of special properties of water. The special properties of water include all of the following EXCEPT<n>A.cohesion<n>B.adhesion<n>C.capillary action<n>D.hydrophobicity[SEP]D
Which of the following statements best explains why Mendel's principle of segregation was deemed a law?<n>A.Mendel's work with pea plants and his conclusions have been described in many sources.<n>B.The patterns of trait inheritance observed in pea plants were repeatedly demonstrated in other eukaryotes.<n>C.Chromosomes were found to contain the genetic information for traits.<n>D.The discovery of the structure of D N A supported Mendel's observations and laws.[SEP]B
Protein that prevents the binding of RNA polymerase to the promoter site.<n>A.Enhancer<n>B.Repressor<n>C.Operator<n>D.Promoter[SEP]B
Which of these is the smallest unit that natural selection can change?<n>A.a species' gene frequency<n>B.a population's gene frequency<n>C.an individual's genome<n>D.an individual's genotype[SEP]B
Which of these is the smallest unit upon which natural selection directly acts?<n>A.a species' gene frequency<n>B.a population's gene frequency<n>C.an individual's genome<n>D.an individual's phenotype[SEP]D
A chemical agent is found to denature all enzymes in the synaptic cleft. What effect will this agent have on acetylcholine?<n>A.Acetylcholine will not be released from the presynaptic membrane.<n>B.Acetylcholine will not bind to receptor proteins on the postsynaptic membrane.<n>C.Acetylcholine will not diffuse across the cleft to the postsynaptic membrane.<n>D.Acetylcholine will not be degraded in the synaptic cleft.[SEP]D
The reaction A + B → C is catalyzed by enzyme K. If the reaction is in equilibrium, which of the following would allow more product C to be produced?<n>A.removing some of reactant A<n>B.removing some of reactant C<n>C.adding more enzyme K<n>D.increasing the temperature of the system[SEP]B
A new plant was discovered and determined to have an unusually low number of stomata on the undersides of its leaves. For what environment would this plant most likely be best adapted?<n>A.Cold and rainy<n>B.Humid and sunny<n>C.Hot and humid<n>D.Hot and dry[SEP]D
Which of the following adaptive features would least likely be found in an animal living in a hot arid environment?<n>A.Long loops of Henle to maximize water reabsorption<n>B.Storage of water in fatty tissues<n>C.Large ears to aid in heat dispersion<n>D.Short loops of Henle to maximize water secretion[SEP]D
Certain populations of finches have long been isolated on the Galapagos Islands off the western coast of South America. Compared with the larger stock population of mainland finches, these separate populations exhibit far greater variation over a wider range of species. The variation among these numerous finch species is the result of<n>A.convergent evolution<n>B.divergent evolution<n>C.disruptive selection<n>D.stabilizing selection[SEP]B
Memory loss would most likely be due to a malfunction of which part of the brain?<n>A.Medulla<n>B.Cerebellum<n>C.Cerebrum<n>D.Pons[SEP]C
The major difference between cartilage and bone is that cartilage<n>A.is a part of the skeletal system<n>B.is composed of collagen and salts<n>C.lacks blood vessels and nerves<n>D.secretes a matrix[SEP]C
Viral transduction is the process by which viruses carry bacterial DNA from one bacterial cell to another. In what way does this process play a role in bacterial evolution?<n>A.By making the bacterial cell more resistant to predators<n>B.By directly creating new species of bacteria<n>C.By increasing genetic variation of the bacteria<n>D.By selecting for viruses better able to infect bacteria[SEP]C
Cattle breeders have improved the quality of meat over the years by which process?<n>A.artificial selection<n>B.directional selection<n>C.stabilizing selection<n>D.A and B[SEP]D
The fluidity of the plasma membrane can vary in response to temperature changes. For bacteria and yeast cells, which of the following would be a viable strategy to maintain homeostasis of the plasma membrane in a temperature-varying environment?<n>A.Increase the concentration of solutes in the cytosol.<n>B.Change the ratio of phospholipids with double covalent bonds in their tails to those without double covalent bonds in their tails.<n>C.Replace phospholipids with glucose molecules.<n>D.Exchange phospholipids from one side of the plasma membrane to the other.[SEP]B
You are told that in a population of guinea pigs, 4 percent are black (recessive) and 96 percent are brown. Which of the following is the frequency of the heterozygous condition?<n>A.16 percent<n>B.32 percent<n>C.40 percent<n>D.48 percent[SEP]B
Of the following anatomical structures, which is homologous to the wing of a bird?<n>A.Dorsal fin of a shark<n>B.Hindlimb of a kangaroo<n>C.Wing of a butterfly<n>D.Flipper of a cetacean[SEP]D
Darwin's mechanism of natural selection required long time spans in order to modify species. From whom did Darwin get the concept of Earth's ancient age?<n>A.Georges Cuvier<n>B.Charles Lyell<n>C.Alfred Wallace<n>D.Thomas Malthus[SEP]B
A researcher is experimenting with nerve transmission using neurons from a giant squid. At the beginning of the experiment, the axon is at rest and has a threshold measured at –70 mV at 37oC. The axon receives one stimulus that triggers one action potential in the axon. Subsequent stimuli are much stronger. Which of the following statements explains what happens when several strong stimuli are experienced by the axon?<n>A.The axon becomes hyperpolarized to –90 mV.<n>B.The axon becomes hyperpolarized to –50 mV.<n>C.The strength of the action potential becomes greater.<n>D.The frequency of the action potential increases.[SEP]D
Refer to question 15 for details on the squirrel population. Which of the following conditions is required to keep this population in Hardy-Weinberg equilibrium?<n>A.Random mating<n>B.Genetic drift<n>C.Mutation<n>D.Gene flow[SEP]A
The structure of ATP synthase in the plasma membranes of bacteria is nearly identical to that in the mitochondria and chloroplasts of eukaryotic cells. This similarity best supports which of the following hypotheses?<n>A.Eukaryotic and prokaryotic cells share a common ancestor.<n>B.Mitochondria are derived from ancient aerobic bacteria, and chloroplasts are derived from ancient photosynthetic bacteria.<n>C.The similarity of ATP synthase in bacteria, mitochondria, and chloroplasts is an example of convergent evolution.<n>D.Mitochondria and chloroplasts escaped from eukaryotic cells and formed aerobic and photosynthetic prokaryotes.[SEP]B
A researcher grows a population of ferns in her laboratory. She notices, after a few generations, a new variant that has a distinct phenotype. When she tries to breed the original phenotype with the new one, no offspring are produced. When she breeds the new variants, however, offspring that look like the new variant result. Which of the following is likely to exhibit the process described earlier?<n>A.Fallow deer<n>B.Fruit flies<n>C.Grass<n>D.Spotted toads[SEP]C
The average birth weight for human babies is about 3 kg. Which of the following terms best describes this?<n>A.artificial selection<n>B.directional selection<n>C.stabilizing selection<n>D.disruptive selection[SEP]C
Some strains of viruses can change normal mammalian cells into cancer cells in vitro. This transformation of the mammalian cell is usually associated with the<n>A.formation of a pilus between the mammalian cell and the virus<n>B.incorporation of the viral genome into the mammalian cell's nuclear DNA<n>C.conversion of the host's genome into the viral DNA<n>D.release of spores into the mammalian cell[SEP]B
The Darwinian fitness of an individual is measured most directly by<n>A.the number of its offspring that survive to reproduce.<n>B.the number of "good genes" it possesses.<n>C.the number of mates it attracts.<n>D.its physical strength.[SEP]A
Hemoglobin is a molecule that binds to both O2 and CO2. There is an allosteric relationship between the concentrations of O2 and CO2. Hemoglobin's affinity for O2<n>A.decreases as blood pH decreases<n>B.increases as H+ concentration increases<n>C.increases in exercising muscle tissue<n>D.decreases as CO2 concentration decreases[SEP]A
A researcher grows a population of ferns in her laboratory. She notices, after a few generations, a new variant that has a distinct phenotype. When she tries to breed the original phenotype with the new one, no offspring are produced. When she breeds the new variants, however, offspring that look like the new variant result. Which of the following could possibly characterize the new variant?<n>A.Adaptive radiation<n>B.Divergent selection<n>C.Equilibrium<n>D.Polyploidy[SEP]D
What is the best explanation for the fact that tuna, sharks, and dolphins all have a similar streamlined appearance?<n>A.They all share a recent common ancestor.<n>B.They all sustained the same set of mutations.<n>C.They acquire a streamlined body type to survive in their particular environment.<n>D.The streamlined body has a selective advantage in that environment.[SEP]D
In a laboratory exercise, a student cuts disks of plant leaves and puts them in a beaker of water. To help submerge the leaves, a drop of soap is added to the water. How does the soap help submerge the leaf disks?<n>A.The soap molecules enter through the stomata of the leaf and bond to oxygen molecules.<n>B.The soap molecules bond to air bubbles on the surface of the leaf and remove them.<n>C.The soap molecules decrease the pH of the water, allowing excess H+ to bond to the leaf surface.<n>D.The hydrophobic regions of the soap molecules attach to the waxy leaf surface, while the hydrophilic regions form hydrogen bonds with the water molecules.[SEP]D
Which describes brightly colored peacocks mating more frequently than drab peacocks?<n>A.artificial selection<n>B.directional selection<n>C.stabilizing selection<n>D.sexual selection[SEP]D
In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenko's attempts in this regard were most in agreement with the ideas of<n>A.Cuvier.<n>B.Hutton.<n>C.Lamarck.<n>D.Darwin.[SEP]C
Students are conducting a plant pigment separation exercise that requires them to use a closed chromatography chamber with a small amount of acetone in the bottom of the chamber. Safety warnings for acetone include the statement that it is an eye and skin irritant and has flammable vapors. Of the following‚ which safety precaution should the students take while conducting the exercise?<n>A.Putting on fire-retardant gloves to carry the chamber to a fume hood if the acetone catches fire<n>B.Placing the chamber in a closed, darkened cabinet for the duration of the pigment separation<n>C.Wearing leather gloves and covering the nose and mouth with a particle mask<n>D.Wearing goggles and nitrile-type gloves and keeping all acetone containers closed[SEP]D
Charles Darwin was the first person to propose<n>A.that evolution occurs.<n>B.a mechanism for how evolution occurs.<n>C.that the Earth is older than a few thousand years.<n>D.a mechanism for evolution that was supported by evidence.[SEP]D
Two individuals, one with type B blood and one with type AB blood, have a child. The probability that the child has type O blood is<n>A.0%<n>B.25%<n>C.50%<n>D.100%[SEP]A
In cells, which of the following can catalyze reactions involving hydrogen peroxide, provide cellular energy, and make proteins, in that order?<n>A.Peroxisomes, mitochondria, and ribosomes<n>B.Peroxisomes, mitochondria, and lysosomes<n>C.Peroxisomes, mitochondria, and Golgi apparatus<n>D.Lysosomes, chloroplasts, and ribosomes[SEP]A
A reaction that includes energy as one of its reactants is called a(n)<n>A.exergonic reaction.<n>B.hydrolysis reaction.<n>C.endergonic reaction.<n>D.redox reaction.[SEP]C
Many different fermentation pathways occur in different organisms in nature. For example, skeletal muscle cells convert pyruvate into lactic acid when no oxygen is present. Yeast cells can produce alcohol and carbon dioxide under the same circumstances. However, regardless of the specific reactions, the purpose of glycolysis is an important one. Which statement best describes the importance of glycolysis?<n>A.It produces large amounts of ATP by substrate level phosphorylation.<n>B.It reoxidizes NADH so that glycolysis can continue.<n>C.It produces pyruvate, which is the raw material for oxidative phosphorylation.<n>D.It occurs in the cytoplasm.[SEP]B
Which of the following is not a form of interspecies interaction?<n>A.Commensalism<n>B.Succession<n>C.Mutualism<n>D.Parasitism[SEP]B
Apoptosis, which is programmed cell death, is a necessary process in living organisms. Which of the following is NOT correct about apoptosis?<n>A.It occurs randomly.<n>B.A particular cell dies when it is no longer needed by the organism.<n>C.A cell carries out apoptosis when too many mutations have accumulated.<n>D.Plant cells carry out apoptosis as a defense measure in cells that have been infected by parasites.[SEP]A
Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?<n>A.By identifying the bones as being homologous<n>B.By the principle of convergent evolution<n>C.By proposing that humans, bats, and dolphins share a common ancestor<n>D.A and C only[SEP]D
Tay-Sachs is a disease caused by a recessive allele. Individuals with the genetic disorder usually do not survive more than a few years, and thus are not able to reproduce and pass on the gene. What would explain how this allele and its associated disease is preserved in the population?<n>A.Heterozygous individuals will show no symptoms.<n>B.Spontaneous mutation converts the dominant allele to the recessive form.<n>C.Occasionally the gene will instead increase the fitness of the individual.<n>D.Tay-Sachs is asymptomatic in people who are homozygous recessive.[SEP]A
In the Tularosa Basin of New Mexico are black lava formations surrounded by light-colored sandy desert. Pocket mice inhabit both areas. Dark-colored ones inhabit the lava formations, while light-colored mice inhabit the desert. Which of the following statements is correct about this scenario?<n>A.The two varieties of mice descended from a recent common ancestor.<n>B.The mouse population was originally one population that diverged into two species because of mutations.<n>C.Selection favors some phenotypes over others.<n>D.Originally the mice were all dark colored. As the lava decomposed into sand, the color of some mice changed because that color was favored in that environment.[SEP]C
Which of the following best explains why lignin is important to the evolutionary success of land plants?<n>A.Lignin provides structural support, allowing plants to grow tall.<n>B.Lignin stimulates spore formation, leading to gametogenesis.<n>C.Lignin supplies the developing embryo with essential nutrients, enabling its growth.<n>D.Lignin supplements the absorption of light by chlorophyll, increasing photosynthetic output.[SEP]A
Which of the following describes a symbiotic relationship?<n>A.A tapeworm feeds off of its host's nutrients causing the host to lose large amounts of weight.<n>B.Certain plants grow on trees in order to gain access to sunlight, not affecting the tree.<n>C.Remora fish eat parasites off of sharks; the sharks stay free of parasites, and the remora fish are protected from predators.<n>D.Meerkats sound alarm calls to warn other meerkats of predators.[SEP]C
The endocrine system maintains homeostasis using many feedback mechanisms. Which of the following is an example of positive feedback?<n>A.Infant suckling causes a mother's brain to release oxytocin, which in turn stimulates milk production.<n>B.An enzyme is allosterically inhibited by the product of the reaction it catalyzes.<n>C.When ATP is abundant the rate of glycolysis decreases.<n>D.When blood sugar levels decrease to normal after a meal, insulin is no longer secreted.[SEP]A
Which of the following are characteristics of both bacteria and fungi?<n>A.Cell wall, DNA, and plasma membrane<n>B.Nucleus, organelles, and unicellularity<n>C.Plasma membrane, multicellularity, and Golgi apparatus<n>D.Cell wall, unicellularity, and mitochondria[SEP]A
Which of the following is NOT a characteristic of bacteria?<n>A.Circular double-stranded DNA<n>B.Membrane-bound cellular organelles<n>C.Plasma membrane consisting of lipids and proteins<n>D.Ribosomes that synthesize polypeptides[SEP]B
Which of the following is the source of oxygen produced during photosynthesis?<n>A.H2O<n>B.H2O2<n>C.CO2<n>D.CO[SEP]A
An eager AP Biology student interested in studying osmosis and the movement of water in solutions took a dialysis bag containing a 0.5 M solution and placed it into a beaker containing a 0.6 M solution. Which of the following is true about water potential?<n>A.An eager AP Biology student interested in studying osmosis and the movement of water in solutions took a dialysis bag containing a 0.5 M solution and placed it into a beaker containing a 0.6 M solution. It drives the movement of water from a region of lower water potential to a region of higher water potential.<n>B.Solute potential is the only factor that determines the water potential.<n>C.Pressure potential combines with solute potential to determine the water potential.<n>D.Water potential always drives water from an area of lower pressure potential to an area of higher pressure potential.[SEP]C
Which of the following is a frameshift mutation?<n>A.CAT HAS HIS → CAT HAS HIT<n>B.CAT HAS HIS → CAT HSH ISA<n>C.CAT HAS HIS → CAT HIS HAT<n>D.CAT HAS HIS → CAT WAS HIT[SEP]B
Crossing-over occurs during which of the following phases in meiosis?<n>A.Prophase I<n>B.Metaphase I<n>C.Anaphase I<n>D.Prophase II[SEP]A
When a retrovirus inserted its DNA into the middle of a bacterial gene, it altered the normal reading frame by one base pair. This type of mutation is called<n>A.duplication<n>B.translocation<n>C.inversion<n>D.frameshift mutation[SEP]D
High levels of estrogen from maturing follicles inhibit the release of gonadotropin releasing hormone (GnRH). Which of the following endocrine glands produces GnRH?<n>A.Anterior pituitary<n>B.Posterior pituitary<n>C.Hypothalamus<n>D.Pineal gland[SEP]C
All of the following are examples of hydrolysis EXCEPT<n>A.conversion of fats to fatty acids and glycerol<n>B.conversion of proteins to amino acids<n>C.conversion of starch to simple sugars<n>D.conversion of pyruvic acid to acetyl CoA[SEP]D
This biome has cold winters and is known for its pine forests.<n>A.Desert<n>B.Tundra<n>C.Taiga<n>D.Deciduous forests[SEP]D
Monkeys of South and Central America have prehensile tails, meaning that their tails can be used to grasp objects. The tails of African and Asian monkeys are not prehensile. Which discipline is most likely to provide an evolutionary explanation for how this difference in tails came about?<n>A.Aerodynamics<n>B.Biogeography<n>C.Physiology<n>D.Biochemistry[SEP]B
Viruses are considered an exception to the cell theory because they<n>A.are not independent organisms<n>B.have only a few genes<n>C.move about via their tails<n>D.have evolved from ancestral protists[SEP]A
Which of the following is an example of a detritivore?<n>A.Cactus<n>B.Algae<n>C.Bat<n>D.Fungus[SEP]D
If a forest of fir, birch, and white spruce trees was devastated by fire, which of the following would most likely happen?<n>A.Only animal life would continue to inhabit the region.<n>B.Secondary succession would begin to occur.<n>C.Only tough grasses would appear.<n>D.The number of species would stabilize as the ecosystem matures.[SEP]B
Sickle cell anemia is a disease caused by the substitution of an incorrect nucleotide into the DNA sequence for a particular gene. The amino acids are still added to the growing protein chain, but the symptoms of sickle cell anemia result. This is an example of a<n>A.frameshift mutation.<n>B.missense mutation.<n>C.nonsense mutation.<n>D.thymine dimer mutation.[SEP]B
There are 40 individuals in population 1, all of which have genotype A1A1, and there are 25 individuals in population 2, all of genotype A2A2. Assume that these populations are located far from one another and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation is mostly likely an example of<n>A.genetic drift.<n>B.gene flow.<n>C.disruptive selection.<n>D.discrete variation.[SEP]A
The end product of the alcohol fermentation pathway is the alcohol ethanol. A considerable amount of energy still remains in ethanol, yet ethanol is a waste product for the yeast cells that produce it. What, then, is the purpose of fermentation?<n>A.Fermentation provides CO2 for photosynthesis.<n>B.Fermentation provides CO2 for cellular respiration.<n>C.Yeast cells excrete ethanol in order to provide a defense against invading bacteria.<n>D.Fermentation replenishes the NAD+ necessary for glycolysis to continue.[SEP]D
A cell is placed into a hypertonic environment and its cytoplasm shrivels up. This demonstrates the principle of<n>A.diffusion.<n>B.active transport.<n>C.facilitated diffusion.<n>D.plasmolysis.[SEP]D
Compared to DNA viral replication, RNA viral replication is more susceptible to mutation because<n>A.RNA replication takes place in the cytoplasm, whereas DNA replication takes place in the nucleus.<n>B.RNA viruses replicate much faster than DNA viruses.<n>C.RNA viruses use uracil instead of thymine.<n>D.RNA replication lacks the proofreading functions characteristic of DNA replication.[SEP]D
A child with type A B blood inherits an IA allele from one parent and an IB allele from the other. The child will carry both A and B glycoproteins on the surface of all red blood cells. This pattern of expression is referred to as<n>A.codominance<n>B.epistasis<n>C.polygenic<n>D.linkage[SEP]C
In vertebrate embryos, which of the following developmental processes most directly results in the formation of the three primary germ layers?<n>A.Neurulation<n>B.Blastula formation<n>C.Cleavage<n>D.Gastrulation[SEP]D
DNA sequences in many human genes are very similar to the corresponding sequences in chimpanzees. Which statement gives the most likely explanation of this fact?<n>A.Humans evolved from chimpanzees millions of year ago.<n>B.Chimpanzees evolved from humans millions of years ago.<n>C.Humans and chimpanzees evolved from a recent common ancestor—about 6 million years ago.<n>D.Humans and chimpanzees evolved from a distant common ancestor about 4 billion years ago.[SEP]C
A large island is devastated by a volcanic eruption. Most of the horses die except for the heaviest males and heaviest females of the group. They survive, reproduce, and perpetuate the population. Since weight is highly heritable and the distribution of weights approximates a binomial distribution, the offspring of the next generation would be expected to have<n>A.a higher mean weight compared with their parents<n>B.a lower mean weight compared with their parents<n>C.the same mean weight as members of the original population<n>D.a higher mean weight compared with members of the original population[SEP]D
Natural selection changes allele frequencies in populations because some ____ survive and reproduce more successfully than others.<n>A.alleles<n>B.loci<n>C.gene pools<n>D.individuals[SEP]D
This process has as its products NADP+, ADP, and sugar.<n>A.Glycolysis<n>B.Chemiosmosis<n>C.Fermentation<n>D.Calvin cycle[SEP]D
Warning coloration adopted by animals that possess a chemical defense mechanism.<n>A.Aposomatic coloration<n>B.Batesian mimicry<n>C.Deceptive markings<n>D.Cryptic coloration[SEP]A
Which of these evolutionary agents is most consistent at causing populations to become better suited to their environments over the course of generations?<n>A.Mutation<n>B.Non-random mating<n>C.Gene flow<n>D.Natural selection[SEP]D
A scientist carries out a cross between two guinea pigs, both of which have black coats. Black hair coat is dominant over white hair coat. Three quarters of the offspring have black coats, and one quarter have white coats. The genotypes of the parents were most likely<n>A.bb × bb<n>B.Bb × Bb<n>C.Bb × bb<n>D.BB × Bb[SEP]B
The tandem back-and-forth evolution of closely related species, which is exemplified by predator-prey relationships.<n>A.Divergent evolution<n>B.Convergent evolution<n>C.Parallel evolution<n>D.Coevolution[SEP]D
In the process of generating ATP, hydrogen ions (H+, or protons) are transported across the inner mitochondrial membrane and the thylakoid membrane by a proton pump (an ATPase). You would expect to find similar proton pumps in the plasma membranes of<n>A.bacteria<n>B.mammalian muscle cells<n>C.mammalian nerve cells<n>D.plants and fungi[SEP]A
Crop rotation is the successive planting of different crops on the same land in sequential seasons. Which of the following statements summarizes the most likely benefits of this practice?<n>A.It allows the farmer to plant the crops with the greatest demand in the marketplace.<n>B.It increases crop yields and soil fertility and minimizes pathogen infection and pest infestation.<n>C.It allows the hybridization of successive crops and the development of newer varieties of crop plants.<n>D.It decreases the need for diverse harvesting equipment and minimizes production costs.[SEP]B
The base composition of DNA varies from one species to another. Which of the following ratios would you expect to remain constant in the DNA?<n>A.Cytosine : Adenine<n>B.Pyrimidine : Purine<n>C.Adenine : Guanine<n>D.Guanine : Deoxyribose[SEP]B
Which is a true statement concerning genetic variation?<n>A.It is created by the direct action of natural selection.<n>B.It arises in response to changes in the environment.<n>C.It must be present in a population before natural selection can act upon the population.<n>D.It tends to be reduced by the processes involved when diploid organisms produce gametes.[SEP]C
The primary site of glucose reabsorption is the<n>A.glomerulus<n>B.proximal convoluted tubule<n>C.loop of Henle<n>D.collecting duct[SEP]B
Which statement about natural selection is most correct?<n>A.Adaptations beneficial in one habitat should generally be beneficial in all other habitats as well.<n>B.Different species that occupy the same habitat will adapt to that habitat by undergoing the same genetic changes.<n>C.Adaptations beneficial at one time should generally be beneficial during all other times as well.<n>D.Well-adapted individuals leave more offspring, and thus contribute more to the next generation's gene pool, than do poorly adapted individuals.[SEP]D
This process couples the production of ATP with the movement of electrons down the electron transport chain by harnessing the driving force created by a proton gradient.<n>A.Glycolysis<n>B.Chemiosmosis<n>C.Fermentation<n>D.Calvin cycle[SEP]B
A piece of potato is dropped into a beaker of pure water. Which of the following describes the activity after the potato is immersed into the water?<n>A.Water moves from the potato into the surrounding water.<n>B.Water moves from the surrounding water into the potato.<n>C.Potato cells plasmolyze.<n>D.Solutes in the water move into the potato.[SEP]B
