Biology 1202 Mastering Biology Questions Exam One

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Which variable is likely to undergo the largest change in value resulting from a mutation that introduces a new allele into a population at a locus for which all individuals formerly had been fully homozygous? A.geographic variability B.average heterozygosity C. nucleotide variability D.average number of loci

A mutation occurs when _____. A.there is a change in the DNA sequence of a gene B. individuals enter a population C.population sizes are small D. some individuals leave more offspring than other individuals E. individuals leave a population

According to the phylogenetic species concept, what is a species? A. a set of organisms with a unique genetic history B. a population that interbreeds and produces fertile offspring C. a population that is physically able to mate even if there are no offspring or the offspring are infertile D. a clone of genetically identical organisms E. a population with a distinct fossil record

All the genes in a population are that population's _____. A.gene pool B.Hardy-Weinberg C.genotype D.fitness E.phenotype

Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence? A.genetic drift B. gene flow C. natural selection D. nonrandom mating E. mutation

Crossing over, resulting in an increase in genetic variation, occurs between _____. A.nonsister chromatids of homologous chromosomes B.nonsister chromatids of nonhomologous chromosomes C. sister chromatids of homologous chromosomes D.sex cells and somatic cells E.sister chromatids of nonhomologous chromosomes

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 A.humans and chimpanzees share a relatively recent common ancestor. B.convergent evolution led to the DNA similarities. C. humans evolved from chimpanzees. D.chimpanzees evolved from humans. E. humans and chimpanzees are not closely related.

In the formula for determining a population's genotype frequencies, the 2 in the term 2pq is necessary because A. heterozygotes can come about in two ways. B. the population is diploid. C. the population is doubling in number. D. heterozygotes have two alleles.

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? A.The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical. B. Both species are well adapted to their particular environments. C.The two species live at great distance from each other. D.The sizes of the structures in adult members of both species are similar in size.

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation? A. stabilizing selection B. sexual selection C. artificial selection D. directional selection E. disruptive selection

Rabbit ear size tends to decrease as latitude increases. This is an example of _____. A. a cline B. genetic drift C. heterozygote advantage D.artificial selection E.polymorphism

The ease with which humans travel across the globe is likely to increase _____. A.gene flow B.natural selection C. mutation D. genetic drift E. all of these

There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception? A. Advantageous alleles do not arise on demand. B. Adaptations are often compromises. C. Evolution can be influenced by environmental change. D. A population's evolution is limited by historical constraints.

True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating. A. True B. False

What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals? A. 0.4 B. 80 C. 0.5 D. 0.1

Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies? A. Selection B. Inbreeding C. Mutation D. There is no evolutionary force that results in adaptive changes in allele frequencies.

Which of the following statements best describes theories? A. They are supported by, and make sense of, many observations. B.They cannot be tested because the described events occurred only once. C.They are nearly the same things as hypotheses. D. They are predictions of future events.

Which of the following statements is not a part of the Hardy-Weinberg principle? A. The genotype frequencies in the offspring generation must add up to two. B. Even if allele A1 is dominant to allele A2 , it does not increase in frequency. C. When alleles are transmitted according to the rules of Mendelian inheritance, their frequencies do not change over time. D. If allele frequencies in a population are given by p and q, then genotype frequencies will be given by p 2, 2pq, and q 2 for generation after generation.

From his observations of organisms in the Galapagos islands, Darwin reasoned that _____. A.all island species should be similar to each other B.organisms had adapted to new environments, giving rise to new species C.the shape of a bird's beak does not affect its ability to survive and reproduce D.the organisms in the Galapagos had been specially created to thrive in that environment E. none of the above

A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of A. a bottleneck. B. a cline. C.relative fitness. D. geographic variation. E. genetic drift.

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true? A.Species X and Y share a common ancestor that is still extant (in other words, not yet extinct). B.Species X and Y share a greater number of homologies with each other than either does with species Z. C.Species X and Y are the result of artificial selection from an ancestral species Z. D.Species X and Y are not related to species Z. E.Species X, Y, and Z share a common ancestor, but nothing more can be claimed than this.

Genetic drift is a process based on _____. A. immigration B. the role of chance C. mutation D. emigration E. differential reproductive success correlated to the relationship between a phenotype and the environment

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. A change occurs in the environment. 3. Genetic frequencies within the population change. 4. Poorly adapted individuals have decreased survivorship. A.2 → 4 → 3 → 1 B.2 → 4 → 1 → 3 C.4 → 2 → 1 → 3 D.4 → 1 → 2 → 3 E.4 → 2 → 3 → 1

How does diploidy help to preserve genetic variation? A. It fosters the exchange of genes between different populations. B. It allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation in heterozygotes. C. It restricts the gene pool by chance events such as floods or other catastrophic events. D. It allows the frequency of a recessive allele in a population to be predicted under certain conditions. E. It helps individual organisms make a greater contribution to the gene pool of the next generation.

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement? A.If an individual acquires new genes by engulfing, or being infected by, another organism, then a new genetic species will be the result. B.If natural selection can change one gene's frequency in a population over the course of generations then, given enough time and enough genes, natural selection can cause sufficient genetic change to produce new species from old ones. C.A single mutation in a single gene in a single gamete will, if perpetuated, produce a new species within just two generations. D. If an individual's somatic cell genes change during its lifetime, making it more fit, then it will be able to pass these genes on to its offspring.

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing? A. These genes should continue to be maintained in case the antibiotics ever appear. B. These bacteria should be outcompeted and replaced by bacteria that have lost these genes. C.The bacteria should start making and secreting their own antibiotics. D.The bacteria should try to make the cost worthwhile by locating, and migrating to, microenvironments where traces of antibiotics are present.

If two modern organisms are distantly related in an evolutionary sense, then one should expect that A. their chromosomes should be very similar. B. they should share fewer homologous structures than two more closely related organisms. C. they shared a common ancestor relatively recently. D. they live in very different habitats. E. they should be members of the same genus.

If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be A. 46%. B. 54%. C. 23%. D. There is not enough information to say.

In 1959, doctors began using the powerful antibiotic methicillin to treat infections of Staphylococcus aureus, but within two years, methicillin-resistant strains of S. aureus (MRSA) appeared. How did the resistant strains of S. aureus emerge? A.In response to treatment of Staphylococcus aureus infections with methicillin, bacterial populations gradually began to synthesize cell walls using a protein that was not affected by methicillin. B. Staphylococcus aureus bacteria that were able to synthesize cell walls using a protein that was not affected by methicillin survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common. C.In response to treatment of Staphylococcus aureus infections with methicillin, some bacteria began to synthesize cell walls using a protein that was not affected by methicillin. These bacteria survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common.

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype? A. 0.42 B. 0.81 C. 0.32 D. 0.20 E. Genotype frequency cannot be determined from the information provided.

Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans. A.disease B. genetic drift C. natural selection D. mutation E. gene flow

Natural selection is based on all of the following except A.genetic variation exists within populations. B. individuals adapt to their environments and, thereby, evolve. C. the best-adapted individuals tend to leave the most offspring. D.populations tend to produce more individuals than the environment can support. E. individuals who survive longer tend to leave more offspring than those who die young.

The role that humans play in artificial selection is to A. train organisms to breed more successfully. B. choose which organisms breed, and which do not. C.determine who lives and who dies. D.perform artificial insemination. E.create the genetic variants, which nature then selects.

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. With respect to the sickle-cell allele, what should be true of the β hemoglobin locus in U.S. populations of African-Americans whose ancestors were from equatorial Africa? 1. The average heterozygosity at this locus should be decreasing over time. 2. There is an increasing heterozygote advantage at this locus. 3. Diploidy is helping to preserve the sickle-cell allele at this locus. 4. Frequency-dependent selection is helping to preserve the sickle-cell allele at this locus. A. 1 only B. 1 and 3 C. 2 and 3 D. 1, 2, and 3 E. 1, 2, and 4

Use this information to answer the following question. A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time? A. The genotype AA is lethal. B. The two phenotypes are about equally adaptive under laboratory conditions. C. There has been a high rate of mutation of allele A to allele a. D. The population is undergoing genetic drift. E. There has been sexual selection favoring allele a.

Use this information to answer the following question. You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown. In which population would it be least likely that an accident would significantly alter the frequency of the brown allele? A. population A B. population B C. population C D. They are all the same. E.It is impossible to tell from the information given.

What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals? A. The frequency of the A1 allele is 0.1. B. The frequency of the A1 allele is 0.3. C. The frequency of the A1 allele is 0.7. D. The frequency of the A1 allele is 0.5.

Which of the following pieces of evidence most strongly supports the common origin of all life on Earth? A. All organisms require energy. B. All organisms use essentially the same genetic code. C. All organisms show heritable variation. D.All organisms reproduce. E.All organisms have undergone evolution.

Which of the following statements about species, as defined by the biological species concept, is (are) correct? I. Biological species are defined by reproductive isolation. II. Biological species are the model used for grouping extinct forms of life. III. The biological species is the largest unit of population in which successful interbreeding is possible. A. I and II B. I and III C. II and III D.I, II, and III

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained? A. S. aureus can resist vaccines. B. Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency. C. In response to the drug, S. aureus began making drug-resistant versions of the protein targeted by the drug. D.The drug caused the S. aureus DNA to change. E.A patient must have become infected with MRSA from another community.

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. The actual forelimbs of these mammals do not seem to be optimally arranged because A. though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design. B. in many cases, phenotype is not merely determined by genotype, but by the environment as well. C. natural selection is generally limited to modifying structures that were present in previous generations and in previous species. D. natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time.

Allele frequencies in a gene pool may shift randomly and by chance. What is this random shift called? A. gene flow B. directional selection C. genetic drift

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the frequency of individuals that are homozygous for this allele? A. 49.0 B. 0.9 C. 0.09 D. 0.49 E. 9.0

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes. If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet, about how many people will have attached earlobes when the planet's population reaches 10,000? A. 1,000 B. 800 C. 100 D. 400 E. 10,000

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes. Which of these is closest to the allele frequency in the founding population? A. 0.5 a, 0.5 A B. 0.2 a, 0.8 A C. 0.1 a, 0.9 A D. 0.8 a, 0.2 A E. 0.4 a, 0.6 A

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 A. common environments are inhabited by the same organisms. B. the island forms and mainland forms are converging. C.island forms and mainland forms descended from common ancestors. D. island forms and mainland forms have identical gene pools. E. the islands were originally part of the continent.

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree? A.Some of the organisms depicted by the tree had lived in different habitats. B. The skeletal remains of the organisms depicted by the tree were incomplete (in other words, some bones were missing). C.Relationships between DNA sequences among the species did not match relationships between skeletal patterns. D.None of the organisms depicted by the tree ate the same foods. E.Transitional fossils had not been found.

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses? A.Natural selection accounts for these losses by the principle of use and disuse. B.The ancestors of these organisms experienced harmful mutations that forced them to find new habitats that these species had not previously used. C. Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits. D. Natural selection cannot account for losses, only for innovations.

The evolutionary effects of genetic drift are greatest when _____. A. intraspecific competition is intense B. intraspecific competition is weak C. the population size is small D. the population size is large E. sexual selection occurs

The fruit fly Drosophila melanogaster has an allele that confers resistance to DDT and similar insecticides. Laboratory strains of D. melanogaster have been established from flies collected in the wild in the 1930s (before the widespread use of insecticides) and the 1960s (after 20 years of DDT use). Lab strains established in the 1930s have no alleles for DDT resistance. In lab strains established in the 1960s, the frequency of the DDT-resistance allele is 37%. Which statement is correct? A. Alleles for DDT resistance arose by mutation during the period of DDT use because of selection for pesticide resistance. B. Resistance to DDT evolved in some fruit flies in order to allow them to survive. C. The evolutionary fitness associated with the heritable trait of DDT resistance changed once DDT use became widespread.

The wing of a bat is homologous to the _____ of a whale. A. tail B.blowhole C.flipper D.baleen E.rib cage

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. In the United States, the parasite that causes malaria is not present, but African-Americans whose ancestors were from equatorial Africa are present. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa? A. directional selection; disruptive selection B. disruptive selection; directional selection C. directional selection; stabilizing selection D. disruptive selection; stabilizing selection E. stabilizing selection; disruptive selection

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. The sickle-cell allele is pleiotropic (i.e., it affects more than one phenotypic trait). Specifically, this allele affects oxygen delivery to tissues and affects one's susceptibility to malaria. Under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." Such individuals remain less susceptible to malaria. Thus, pleiotropic genes/alleles such as this can help explain why A. chance events can affect the evolutionary history of populations. B. evolution is limited by historical constraints. C. adaptations are often compromises. D. new advantageous alleles do not arise on demand.

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. Again, if this population were in equilibrium and if the sickle-cell allele is recessive, what proportion of the population should be susceptible to sickle-cell anemia under typical conditions? A. 0.16 B. 0.32 C. 0.04 D.0.80 E. 0.20

What situation most likely explains the occasional high frequency of certain inherited disorders among human populations established by a small population? A. gene flow B. mutation C. founder effect D. bottleneck effect E. nucleotide variability

Which of the following are basic components of the Hardy-Weinberg model? A.Allele frequencies, number of individuals in the population B. Allele frequencies, phenotype frequencies C. Frequencies of two alleles in a gene pool before and after many random matings D. Allele frequencies in a subset of the population

Which of the following is not an observation or inference on which natural selection is based? A.There is heritable variation among individuals. B.Individuals whose characteristics are best suited to the environment generally leave more offspring than those whose characteristics are less well suited. C. Poorly adapted individuals never produce offspring. D.Only a fraction of an individual's offspring may survive. E.Species produce more offspring than the environment can support.

Which of these conditions should completely prevent the occurrence of evolution in a population over time? A.The population size is large. B.The environment is changing at a relatively slow rate. C.All phenotypic variation between individuals is due only to environmental factors. D.The population lives in a habitat where there are no competing species present.

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to A. transfer only the largest flies. B. shock the flies with a brief treatment of heat or cold to make them more hardy. C. cross your flies with flies from another lab. D. reduce the number of flies that you transfer at each generation. E. change the temperature at which you rear the flies.

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 both 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? A. The amount of available food may have increased. B. The parental generation of squirrels developed better eyesight due to improved diet; the subsequent squirrel generation inherited better eyesight. C. The number of predators that prey upon squirrels may have decreased. D.A and C could be true. E. A, B, and C could be true.

According to the Hardy-Weinberg theorem, the frequencies of alleles in a population will remain constant if _____ is the only process that affects the gene pool. A. mutation B. immigration C. sexual selection D. sexual reproduction E. genetic drift

Blue poppies native to China were grown at a plant-breeding center in California. The plants with the thickest leaves were most likely to survive and reproduce in the drier climate. After several generations, the percentage of thick-leaved plants had increased by 42%. This adaptation of the poppies to their new environment is due to _____. A. genetic drift B. neutral variation C. disruptive selection D. directional selection E. stabilizing selection

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? A.Disuse of an organ may lead to its eventual disappearance. B. If the giraffes did not have to compete with each other, longer necks would not have been passed on to the next generation. C. Spontaneous mutations can result in the appearance of new traits. D. Characteristics acquired during an organism's life are generally not passed on through genes. E. Only favorable adaptations have survival value.

Evolution A. must happen whenever a population is not well-adapted to its environment. B. must happen, due to organisms' innate desire to survive. C. requires that populations become better suited to their environments. D. can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met. E. requires the operation of natural selection.

Homologous pairs of chromosomes are lined up independently of other such pairs during _____. A. anaphase I B. prophase II C. telophase II D. metaphase I E. metaphase II

How many of these statements regarding populations are true? 1. Mature males and females of a population can interbreed with each other. 2. Populations are sometimes geographically isolated from other populations. 3. Biological species are made up of populations. 4. Members of a population tend to be genetically more similar to each other than to members of other populations. 5. Populations have genomes, but not gene pools. A. Only one of these statements is true. B. Two of these statements are true. C. Three of these statements are true. D. Four of these statements are true. E. All five of these statements are true.

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations? A. selection for algae-eaters that become sexually mature at smaller overall body sizes B.selection for drab coloration of the algae-eaters C. selection for algae-eaters that are faster swimmers D.selection for larger female algae-eaters, bearing broods composed of more, and larger, young E. selection for nocturnal algae-eaters (active only at night)

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population? A. 0.64 B. 0.75 C. 0.36 D. 0.80

In the wild, male house finches (Carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colors ranging from pale yellow to bright red. These colors come from carotenoid pigments that are found in the birds' diets; no vertebrates are known to synthesize carotenoid pigments. Thus, the brighter red the male's feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food-gathering efforts (all other factors being equal). During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following is true of this situation? A. There should be directional selection for bright red feathers in males. B. Alleles that promote more efficient acquisition of carotenoid-containing foods by males should increase over the course of generations. C. Alleles that promote more effective deposition of carotenoid pigments in the feathers of males should increase over the course of generations. D. Three of the statements are correct. E. Two of the statements are correct.

Swine are vulnerable to infection by bird flu virus and human flu virus, which can both be present in an individual pig at the same time. When this occurs, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the new virus, and if the new virus is introduced to an environment lacking Tamiflu, then what is most likely to occur? A. If the Tamiflu-resistance gene confers no benefit in the current environment, and has no cost, the virus will become dormant until Tamiflu is present. B. The new virus will maintain its Tamiflu-resistance gene, just in case of future exposure to Tamiflu. C. The Tamiflu-resistance gene will undergo mutations that convert it into a gene that has a useful function in this environment. D. If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Over the course of evolutionary time, what should occur? A. Methylated DNA should become fixed in the gene pools of bacterial species. B. Nonmethylated DNA should become fixed in the gene pools of bacteriophages. C. Methylated DNA should become fixed in the gene pools of bacteriophages. D. Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time. E. Both the first and second responses are correct.

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because A.humans are becoming resistant to bacteria by taking methicillin. B.S. aureus is cultivated by humans to replenish the soil with nutrients. C.humans purposefully raise MRSA in large fermenters in an attempt to make the bacteria ever-more resistant. D.humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin.

The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data? A.Whales are not properly classified as mammals. B.Genes mutate faster in whales than in humans or bats. C. Forelimb evolution was adaptive in people and bats, but not in whales. D.Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy. E. Humans and bats evolved by natural selection, and whales evolved by Lamarckian mechanisms.

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. Although selection is clearly present, if the ideal equilibrium of alleles existed, what should be the proportion of heterozygous individuals in populations that live here? A. 0.04 B. 0.20 C. 0.80 D. 0.32 E. 0.16

What genotype frequencies are expected under Hardy-Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene? A. The expected genotype frequencies are 0.32, 0.64, and 0.04 for A1A1, A1A2 , and A2A2 , respectively. B. The expected genotype frequencies are 0.33, 0.33, and 0.33 for A1A1, A1A2 , and A2A2 , respectively. C. The expected genotype frequencies are 0.25, 0.5, and 0.25 for A1A1, A1A2 , and A2A2 , respectively. D. The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2 , and A2A2 , respectively.

What is the most important factor that holds a gene pool of a species together and prevents speciation? A. sexual selection B. hybridization C. behavioral isolation D. gene flow E. prezygotic barriers

What is the only evolutionary mechanism that consistently leads to adaptive evolution? A. gene flow B. genetic drift C. the bottleneck effect D. natural selection E. neutral variation

Which of the following evolutionary forces could create new genetic information in a population? A. Genetic drift B. Selection C. Nonrandom mating D. Mutation

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true? A.Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation. B. The frequency of the strong-beak alleles increased in each bird as the drought persisted. C.Each bird evolved a deeper, stronger beak as the drought persisted. D. Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.

A challenge to traditional (pre-1860) ideas about species came from embryology, when it was discovered that _____. A. the embryological development of many plants and animals is almost identical B.mutations have a far more dramatic effect on embryos than on adult organisms C. all animals develop similar embryonic gills D. the more advanced the animal, the more slowly it develops E.embryos of dissimilar organisms, such as sharks and humans, resemble each other

A group of small fish live in a lake with a uniformly light-brown sandy bottom. Most of the fish are light brown, but about 10% are mottled. This fish species is often prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction of what will happen to this fish population? A.In two generations, all the fish will be mottled. B.As the mottled fish are eaten, more will be produced to fill the gap. C. There is no way to predict the result. D. The ratios will not change. E. The proportion of mottled fish will increase over time.

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? A.The frequency of DDT application should have been higher. B. Larger doses of DDT should have been applied. C. All habitats should have received applications of DDT at about the same time. D. DDT application should have been continual. E.None of the individual insects should have possessed genomes that made them resistant to DDT.

Every few years a giant axe chops off the head of every person who is over 6 feet tall. How will this affect the human population? A. It will increase in number since shorter people use fewer resources than taller people. B. Genetic drift will play less of a role in the evolution of humans. C. The mutation rate will increase. D. Gene flow will increase. E. Alleles that promote "tallness" will decrease in frequency.

Hardy-Weinberg equilibrium must occur in populations wherein A. no genetic variation exists. B. an allele remains fixed. C. natural selection is not operating. D. All three of the responses above are correct. E.Only two of the responses above are correct.

Heterozygote advantage should be most closely linked to which of the following? A. random selection B. directional selection C. sexual selection D. disruptive selection E. stabilizing selection

Ichthyosaurs were extinct aquatic reptiles distantly related to living lizards. 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 A.examples of convergent evolution. B. homologous. C.adaptations to a common environment. D. Three of the responses above are correct. E. Two of the responses above are correct.

In evolutionary terms, an organism's fitness is measured by its _____. A. stability in the face of environmental change B. genetic variability C. mutation rate D. health E. contribution to the gene pool of the next generation

In human gamete production there is an average of _____ crossover events per chromosome pair. A. 10+ B. 5-6 C. 9-10 D. 0-1 E. 2-3

Of the following anatomical structures, which is homologous to the bones in the wing of a bird? A. bony rays in the tail fin of a flying fish B. cartilage in the dorsal fin of a shark C.bones in the hind limb of a kangaroo D.chitinous struts in the wing of a butterfly E. bones in the flipper of a whale

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? A. by identifying the bones as being homologous structures B. by proposing that humans, bats, and dolphins share a common ancestor C.by the principle of convergent evolution D. Three of the statements above are correct. E.Two of the statements above are correct.

Varieties of Staphylococcus aureus that are resistant to the drug methicillin _____. A.developed in response to the use of methicillin B. already existed in the population before methicillin was developed C. always have an advantage in every environment D.were strongly selected for as methicillin became widely used to treat bacterial infections E.The second and fourth answers are correct.

What is true of natural selection? A. Natural selection is a random process. B. Natural selection creates beneficial mutations. C. The only way to eliminate harmful mutations is through natural selection. D. Mutations occur when directed by the good of the species; natural selection edits out harmful mutations and causes populations to adapt to the beneficial mutations. E. Mutations occur at random; natural selection can preserve and distribute beneficial mutations.

Which of the following is a true statement concerning genetic variation? A. It tends to be reduced by the processes involved when diploid organisms produce gametes. B. A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity. C. It is created by the direct action of natural selection. D. It arises in response to changes in the environment. E.It must be present in a population before evolution can occur in the population.

Which of the following must exist in a population before natural selection can act upon that population? A. variation among individuals in reproductive success B.genetic variation among individuals C. sexual reproduction D.Three of the responses are correct. E.Two of the responses are correct.

Which of the following observations led to Darwin's major inferences? A.Members of a population vary in their heritable traits. B. Body parts that are not used deteriorate over time. C. Organisms only go extinct when catastrophes occur. D.Although organisms can produce huge numbers of offspring, many of these offspring do not survive. E. The first and fourth answers are correct.

Which of these individuals is a homozygous genotype? A.Gg B. Aa C. aG D.AG E. AA

Which statement about variation is true? A. All genetic variation produces phenotypic variation. B.All phenotypic variation is the result of genotypic variation. C. All geographic variation results from the existence of clines. D.All nucleotide variability results in neutral variation. E. None of the above

You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population? A. 0.70 B. 0.07 C. 0.09 D. 0.08 E. Allele frequency cannot be determined from this information.

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