AP BIO EVOLUTION TEST MC

A particular genetic disorder is associated with a single gene with two alleles. Individuals with two recessive alleles are affected. The prevalence of the disorder is 11 in 6,6006,600. Assuming the population is in Hardy-Weinberg equilibrium, which of the following is closest to the frequency of carriers in the general population?

0.02430

Humans vary in their ability to taste the bitter chemical compound phenylthiocarbamide (PTCPTC). The taster phenotype is dominant to the nontaster phenotype. Researchers tested the PTCPTC taster phenotype of individuals from an isolated population. In the sample, 780 individuals were able to taste PTCPTC and 70 individuals were not able to taste PTCPTC. Assuming the population is in Hardy-Weinberg equilibrium, what is the frequency of the non-taster allele?

0.29

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 49 percent of the animals display a recessive trait (bb), 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 proportion of the population is heterozygous (Bb) for this trait?

0.42

A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what was the frequency of allele G in the gray moths that emerged in 1980?

0.50

In a long‑term study of a population of gray squirrels, researchers observed that most of the squirrels had gray fur. However, there were some individuals in the population with white fur (albino). Genetic analysis revealed that the albino condition is expressed by individuals who are homozygous recessive (gg)(gg). Over a ten-year period, the average frequency of albino squirrels in the population was 0.18. If the population is assumed to be in Hardy-Weinberg equilibrium, the average frequency of the dominant allele is closest to which of the following?

0.58

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 49 percent of the animals display a recessive trait (bb), 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 frequency of allele b in the gene pool?

0.70

Gaucher disease type 1 (GD1GD1) is a recessive genetic disease that affects 1 in 900 individuals in a particular population. GD1GD1 is caused by a mutation in the enzyme glucocerebrosidase. Assuming the population is in Hardy-Weinberg equilibrium, calculate the frequency of the wild-type (nonmutant) allele for the enzyme glucocerebrosidase.

0.967

Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of rRNA subunits were determined for the new species. The table below shows the number of nucleotide differences between the species. Which of the following phylogenetic trees is most consistent with the data?

3 4 2 1 5

A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of moths in the natural population was white in 1962 ?

4%

A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of the gray moths that emerged in 1980 was heterozygous?

67%

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following best describes the mechanism behind the change in beak size in the finch population?

A change in gene frequencies in the finch population due to selective pressure from the environmental change

Poaching is the illegal hunting or capturing of wild animals. Both male and female African elephants have tusks that are a significant source of ivory used for ornaments and jewelry. Assuming that the size of the tusks is heritable, which of the following is the most likely long-term effect of poachers targeting African elephants with large tusks?

A decrease in average tusk size because elephants with large tusks are less likely to survive to reproduce

The Stanley Miller apparatus demonstrated that organic molecules could assemble spontaneously in an environment lacking free oxygen and containing water, methane, and ammonia in the presence of an abundant energy source, such as an electric discharge. The research was considered supportive of the organic soup hypothesis, which states that the primitive atmosphere provided inorganic precursors from which organic molecules could have been synthesized in the presence of an energy source. Based on subsequent research, the primordial atmosphere was determined to contain less methane and more carbon dioxide. The new data about the composition of the early atmosphere had which of the following effects on origin-of-life hypotheses?

A new organic soup hypothesis was proposed to account for the new data about the atmosphere.

Evolutionary biologists have observed variation in the average age and size of mature individuals in a population of small freshwater guppies. Guppies found in pools with pike cichlids— a predator fish that preys primarily on larger guppies—reproduce at a young age and are small at maturity. Guppies found in pools with killifish —a different predator fish that preys primarily on smaller guppies—reproduce at an older age and are larger at maturity. Which of the following predicts the most likely outcome of moving a population of guppies from a pool with pike cichlids to a pool with killifish?

After many generations, the offspring of the introduced guppies will mature at an older age and larger size because of selective pressure from the new predator.

One of the oldest known mammalian fossils belongs to a small furry species, Hadrocodium wui, that lived 195 million years ago. For the following 100 million years, only a small number of groups of mammalian fossils are found in the fossil record. By 65 million years ago, the nonavian dinosaurs were extinct. By 55 million years ago, there were 130 mammal genera, including 4,000 different species that occupied a wide variety of habitats. Which of the following best describes the cause of the rapid increase in the number of mammalian species between 65 and 55 million years ago?

After the dinosaur extinction, many ecological niches became available, leading to the adaptive radiation of mammals.

Which of the following is probably the best explanation for the fact that Antarctic penguins cannot fly, although there is evidence that millions of years ago their ancestors could do so?

Ancestral penguins without large wings were better able to swim and feed in the water; therefore they passed their genes for shorter wing structure on to their offspring.

Based on morphological characteristics, the phylogenetic tree above has been developed for species I, II, III, and IV. DNA sequencing has recently been completed for a particular gene found in all four species. The sequencing will provide additional information for answering which of the following questions?

Are species III and IV the most closely related?

The cladogram shown below depicts an accepted model of the evolutionary relationships among selected species. The amino acid at position 104 in the beta-hemoglobin protein for each of these four organisms is listed below. The validity of the cladogram is best supported by molecular evidence for which of the following changes in the amino acid composition of the beta-hemoglobin protein during the evolution of these species?

Arginine to leucine at position X on the cladogram

Different photosynthetic organisms have different types of chlorophyll molecules. The distribution of chlorophylls in several different groups of organisms is shown in Table 1. A plus sign (++) in the table indicates the presence of a chlorophyll, while a minus sign (−−) indicates its absence. Based on the data, which of the following most likely describes the evolutionary relationship among the organisms?

Because all of the organisms contain chlorophyll a, the organisms share a common ancestor.

Which of the following questions about the origin of life on Earth is most scientifically testable?

Can simple organic molecules form spontaneously in an oxygen-free atmosphere?

Students analyzed several photosynthetic eukaryotic organisms in the laboratory to determine their phylogenetic relationships. The organisms were Spirogyra (a green alga), a moss, a spruce tree, and an apple tree. Table 1 compares several characteristics in the organisms (++ indicates the trait is present, −− indicates the trait is absent). Which of the following rows of data listed in table 1 best supports the possibility of a common ancestor for the organisms listed there?

Cell wall composed of cellulose

Ciprofloxacin is given as an antibiotic to healthy livestock to promote efficient weight gain. Strains of the bacterium Campylobacter jejuni naturally colonize the digestive tracts of livestock, and the C. jejuni can be transferred to people through the handling and consumption of contaminated meat. People infected with C. jejuni also are treated with ciprofloxacin. Which of the following is the most likely consequence of adding ciprofloxacin to animal feed?

Ciprofloxacin-resistant strains of C. jejuni will have a selective advantage in the digestive tracts of livestock, increasing the risk of serious infections in people.

Paleoclimatic analysis has generated a claim that there is a possible correlation between an extinction event around 29 million years ago that allowed grasslands to become abundant and the adaptive radiation of several groups of butterflies. Which of the following proposes the best alternative hypothesis for the claim?

Climate analysis conducted by sampling pollen preserved in amber shows an increase in grass pollen 29 million years ago, which indicates there was an increase in grasslands that correlates to an increase in butterfly speciation during the same time period.

A group of students summarized information on five great extinction events. The students are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following would be the most reasonable plan for the students to follow?

Collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones

Staphylococcus aureus is a pathogenic bacterium that can infect a wide range of host species, including humans. S. aureus has a particular protein that binds with hemoglobin from the host organism. Hemoglobin is the iron-containing protein used to transport oxygen in the blood. Since iron is important for growth, S. aureus have evolved the ability to absorb the iron from the host's hemoglobin. Different S. aureus strains preferentially infect different hosts and have different amino acid sequences at their hemoglobin-binding domains (Table 1; letters indicate different amino acids). In an experiment, different S. aureus strains were mixed with hemoglobin from macaque monkeys and their binding ability was measured (Figure 1). The differences in amino acid sequences contributed to the differential binding abilities observed. Which of the following experiments would be most appropriate to determine whether populations of S. aureus are continuously adapting in order to obtain iron from hosts more effectively?

Culture S. aureus bacteria with hemoglobin from a novel host species as the only source of iron for many generations, then compare protein structure from bacteria in this culture with bacteria from the original culture.

Researchers were modeling the effects of repeated cycles of isolation with occasional interbreeding among five hypothetical fish species (species A, B, C, D, and E) found in two separate lakes (lakes II and IIII) that are occasionally joined by flooding, as shown in Figure 1. The research team indicated that species A would be considered to be the single common ancestor of species B, C, D, and E. Figure 1. Current locations of populations of fish species A, B, C, D, and E Which of the following data could best support the claim that species B arose from a speciation event in Lake II?

DNADNA analysis shows fewer differences between species A and species B in Lake II than between species B and the populations in Lake IIII.

A researcher released large numbers of moths into different environments in an attempt to better understand a mechanism of evolution. The moths were released in four trials as described in the table above. Each of the released moths had a small mark on the underside of a wing for identification. After an appropriate amount of time, the researcher recaptured as many of the released moths as possible. Data from the experiment are included in the table above. Which of the following claims is best supported by the data?

Dark-colored moths were more likely to be recaptured in the polluted environment than in the unpolluted environment, suggesting an increased chance of reproductive success.

A species of snail lives in the intertidal zone along the coast of New England. The dark-colored variety of the species is more common in northern New England, the light-colored variety is more common two hundred miles away in southern New England, and both varieties are commonly found together in central New England. Which of the following best explains the observed distribution pattern of the snails?

Dark-colored snails absorb more solar energy and so survive more readily in the colder northern waters.

A widely accepted hypothesis about the origin of life on Earth is that life arose approximately 3.5 billion years ago as the result of a complex sequence of chemical reactions that took place spontaneously in Earth's atmosphere. Another hypothesis about the origin of life suggests that life began somewhere else in the universe and arrived on Earth by chance. Which of the following questions might scientists ask to most reliably determine if there has ever been life on Mars?

Did Mars have the elements present in its atmosphere to support life?

A researcher hypothesizes that RNA molecules were present in the most recent common ancestor of all living organisms. Which of the following scientific questions would best test the hypothesis?

Do any known organisms function entirely without RNA?

Staphylococcus aureus is a pathogenic bacterium that can infect a wide range of host species, including humans. S. aureus has a particular protein that binds with hemoglobin from the host organism. Hemoglobin is the iron-containing protein used to transport oxygen in the blood. Since iron is important for growth, S. aureus have evolved the ability to absorb the iron from the host's hemoglobin. Different S. aureus strains preferentially infect different hosts and have different amino acid sequences at their hemoglobin-binding domains (Table 1; letters indicate different amino acids). In an experiment, different S. aureus strains were mixed with hemoglobin from macaque monkeys and their binding ability was measured (Figure 1). The differences in amino acid sequences contributed to the differential binding abilities observed. Which of the following processes is most consistent with the differences in the amino acid sequences listed in Table 1 ?

Each strain is best adapted to a specific host species.

The cladogram shows shared traits among four plant taxa. Based on the cladogram, which of the following are the traits shared between ferns and pines?

Embryo and xylem only

The fossils in a layer of rock are significantly different from those in the rock layer directly above it. One hypothesis to explain the difference is that a major extinction event occurred at the point in time represented by the transition between the two rock layers. Which of the following is the best plan for collecting data to use in a test of the hypothesis?

Examining the upper part of the lower rock layer for evidence of a catastrophic event, such as the presence of shocked quartz, iridium, or soot particles

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following statements might best explain the increase in average beak size in the finch population during the drought?

Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.

The table shows the changes in allele frequencies of a specific gene in two populations of randomly mating small mammals after 30 years. The populations inhabit adjacent equatorial islands that have similar topography and climate. Which of the following is the most reliable conclusion that can be drawn from analysis of the data above?

Genetic drift has occurred in population 1.

A researcher is studying two different species. Which of the following sets of observations would best support the claim that the two species have structural similarities as a result of convergent evolution?

Genetic similarity - low Function of structure - same Form of structure - Different

Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms from all three domains, Archaea, Bacteria, and Eukarya. Which of the following hypotheses could be best supported by this evidence?

Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life.

Low doses of antibiotics are often added to livestock feed to increase production. Studies have shown that bacterial populations constantly exposed to the sublethal doses can evolve resistance to the antibiotics. A research group claimed that when a population of bacteria are constantly exposed to sublethal doses of streptomycin, their fitness declines due to the increased energy requirements for survival in the presence of the antibiotic. For subsequent studies, the researchers wish to determine whether adding a low, sublethal dose of an additional antibiotic causes further decline in the fitness of the bacteria. Which of the following best represents the next step the researchers should take with respect to experimental design?

Group 1: low dose of streptomycin ++ no dose of additional antibiotic Group 2: low dose of streptomycin ++ low dose of additional antibiotic

Which of the following describes a scenario that would result in the phenotypic change shown in the graph?

House sparrows that lay smaller-than-average clutches of eggs produce fewer viable offspring, while larger-than-average clutches of eggs result in malnourished chicks that have a higher mortality rate.

Over many generations, two populations of the same species can diverge into separate species through reproductive isolation. The figures below represent a model of speciation and show the results of matings between individuals from two diverging populations at four different stages of speciation. The males represented in the model are heterogametic, which means they have two different sex-determining chromosomes, XY The females are homogametic, which means they have two similar sex-determining chromosomes The offspring from each mating are labeled interpopulation hybrids. Figure 1 shows the results of a mating between a male and a female from the two populations. In each subsequent figure, the males are from one of the diverging populations and the females are from the other population. The fertility and viability of the offspring from each mating are indicated in the figures Based on the model of speciation presented, which of the following describes the most likely consequence to the populations over time?

Hybrid individuals are less likely to pass their genetic information on to subsequent generations.

A scientist used the amino acid sequence of cytochrome c in different species to consider evolutionary relationships. The data below summarize the number of differences in the amino acid sequences of cytochrome c found in selected species. Which of the following phylogenetic trees can be supported by the data?

I and II only

Some cells release active signaling proteins when membrane-bound precursor proteins are cleaved by proteolytic enzymes. The signaling proteins can then bind to receptors on the surface of a target cell, thereby activating an intracellular signaling pathway and eliciting a response from the target cell. This mechanism of activating receptor-binding signaling proteins has been observed in a variety of organisms from bacteria to humans. Many of the enzymes responsible for proteolysis of membrane-bound precursor proteins have been isolated and characterized. Which of the following questions would be most appropriate to investigate whether the proteolytic enzymes are evolutionarily conserved among species?

If a proteolytic enzyme from one species is incubated with a precursor protein from another species, does correct cleavage occur?

Figure 1 compares two models of speciation, A and B. Figure 1. A comparison of two speciation models Which of the following best explains how the ecological conditions are likely to be different in the two models?

In model A the ecological conditions change gradually over a long period of time; in model B the ecological conditions remain unchanged for long periods of time and then change drastically.

While there is only one species of Galápagos Island tortoise, there are several subspecies. Larger islands with more wet highlands have lush vegetation near the ground. Tortoises there tend to have high-domed shells and shorter necks, which restrict upward head movement. They also have shorter limbs. They are the heaviest and largest of the subspecies. Smaller, drier islands are inhabited by tortoises with longer necks and limbs and with shells that are elevated above the neck, which allow them to browse taller vegetation. Based on the information given, which of the following is a plausible explanation for the ancestry of the tortoise subspecies?

Individuals with different adaptations in shell shape and leg length best exploited the food resources and left more surviving offspring on each island.

Chytridiomycosis is a potentially lethal fungal infection that adversely affects some frog populations. The incidence and severity of the fungal infection can vary over time. Which of the following statements best describes the changes in the frog population that are depicted in the model above?

Infected individuals gradually died out, and genetically resistant individuals became more common. The frog population recovered because of the increased frequency of resistant individuals.

Figure 1. For paired groups of organisms, a comparison of the number of amino acid substitutions in cytochrome cc with the time since the groups diverged from a common ancestor Researchers analyzed the amino sequence of the protein cytochrome cc in various groups of organisms and determined the number of amino substitutions that have occurred in the different groups of organisms. They plotted the data with respect to the time since divergence of the members of paired groups from a common ancestor (Figure 1). Based on the data, which of the following organisms are most distantly related?

Insects and vertebrates

Pesticides are chemicals that are often sprayed on crops to kill plant-eating insects, preventing damage to the crops. While pesticides are effective initially, many researchers claim that any single pesticide will see reduced effectiveness in as little as ten to fifteen years. Which of the following best supports the claim by scientists that the pesticides will eventually lose their effectiveness?

Insects that are naturally resistant to the pesticide will survive and reproduce more than the insects that are sensitive to the pesticide.

Over many generations, two populations of the same species can diverge into separate species through reproductive isolation. The figures below represent a model of speciation and show the results of matings between individuals from two diverging populations at four different stages of speciation. The males represented in the model are heterogametic, which means they have two different sex-determining chromosomes, XY The females are homogametic, which means they have two similar sex-determining chromosomes The offspring from each mating are labeled interpopulation hybrids. Figure 1 shows the results of a mating between a male and a female from the two populations. In each subsequent figure, the males are from one of the diverging populations and the females are from the other population. The fertility and viability of the offspring from each mating are indicated in the figures In a separate investigation, individual mice from two populations that in nature are geographically isolated from each other are mated in the laboratory. The hybrid offspring were then mated with individuals from either of the original populations. Only the female hybrid offspring were fertile. The experimental results are most consistent with which of the stages that are depicted in the model?

Intermediate stage (Figure 2)

Which of the following observations best supports the hypothesis that a large object collided with Earth in a period of time associated with a mass extinction?

Iridium, which is common in meteorites but rare on Earth, is found in sedimentary rock that contains the last appearance of many species in the fossil record.

Scientists are studying several populations of finches on neighboring islands in the South Pacific. Previous genetic analysis has shown that a single gene controls tail-feather length in the finch populations and that the allele for long tail feathers L is dominant to the allele for short tail feathers l On two separate islands, the scientists recorded the number of finches with long tail feathers and the number of finches with short tail feathers. The results are shown in the table below.

LL low lL high equal ll slightly higher than LL

On a large volcanic island, researchers are studying a population of annual herbaceous plants. Which of the following observations best supports the prediction that speciation will occur within the existing plant population?

Lava has separated the population into two areas: an upland forest and a lowland marsh.

Rock pocket mice live in the deserts of the American southwest. Ancestral pocket mice all had light-colored coats that blended in with the region's rocks and sandy soil, keeping the mice hidden from predatory owls. About 1.7 million years ago, a series of volcanic eruptions spewed out wide trails of black lava into the middle of rock pocket mouse territory. Currently there are two color morphs of rock pocket mice: light-colored mice that are typically found in habitats with sandy soil, and dark-colored mice that are typically found in habitats with dark-colored lava rocks. Which of the following best justifies the claim that alleles that may be adaptive in one type of environment can be deleterious in another because of different selective pressures?

Light-colored mice are significantly more susceptible to predation by owls in habitats with lava rocks than in habitats with sandy soil.

The bird, Parus major, is commonly found in man-made habitats. During the summer these birds primarily feed on insects, and in the winter, when insects are scarce, they forage in gardens and bird feeders for seeds, nuts, and berries. Recently, climate change has led to a decrease in food available from gardens, and scientists have observed that the average beak length of the birds has increased. Which of the following best explains the directional shift in beak length in these birds?

Longer beaks allow the birds to better access seeds in bird feeders.

A scientist used the amino acid sequence of cytochrome c in different species to consider evolutionary relationships. The data below summarize the number of differences in the amino acid sequences of cytochrome c found in selected species. Interpretation of the data supports which of the following statements?

Mammals are more closely related to reptiles than they are to fish.

Over several years, bacteria were isolated from members of a human population and tested for antibiotic resistance. The percent of bacterial isolates that were found to be antibiotic resistant is presented in the graph above for each year of the study. Which of the following conclusions is best supported by the information presented in the graph?

Natural selection over multiple generations is favoring antibiotic resistance in the population of bacteria.

Researchers observed selected internal structures of four different microscopic organisms as part of a larger study on the divergence between eukaryotes and prokaryotes. Their observations are recorded in Figure 1. Figure 1. Selected cellular structures in four organisms Which organism would the researchers most likely predict to be the most distantly related to eukaryotes?

Organism I

The table above shows the presence (+) or absence (-) of three different derived characters (vascular tissue, seeds, and flowers) for several selected plant species. The cladogram below was created based on the information in the table to represent groups of related species. The presence of the derived characters is indicated with arrows. Group IV of the cladogram most likely includes which of the following species?

P and S only

The hormone prolactin has varying effects in many different animal species. All vertebrates produce prolactin, which is involved in signal transduction pathways. In mammals, prolactin stimulates the production of milk in mammary glands. In fish, prolactin plays an important role in osmoregulation. In birds, prolactin is involved in lipid metabolism. Which of the following best explains the presence of prolactin in various vertebrate species?

Prolactin is a homologous hormone because it has a common origin but different functions in various species.

A scientist is attempting to provide support for the hypothesis that RNARNA was the first genetic material. Which of the following would be a workable alternate hypothesis?

RNARNA can be observed to self-replicate without the assistance of proteins, while DNADNA always requires protein-based enzymes to replicate.

Rhagoletis pomonella is a parasitic fly native to North America that infests fruit trees. The female fly lays her eggs in the fruit. The larvae hatch and burrow through the developing fruit. The next year, the adult flies emerge. Prior to the European colonization of North America, the major host of Rhagoletis was a native species of hawthorn, Crataegus marshallii. The domestic apple tree, Malus domestica, is not native to North America, but was imported by European settlers in the late 1700s and early 1800s. When apple trees were first imported into North America, there was no evidence that Rhagoletis could use them as hosts. Apples set fruit earlier in the season and develop faster, where hawthorns set later and develop more slowly. Recent analysis of Rhagoletis populations has shown that two distinct populations of flies have evolved from the original ancestral population of flies that were parasitic on hawthorns. One population infests only apple trees, and the other infests only hawthorns. The life cycles of both fly populations are coordinated with those of their host trees. The flies of each population apparently can distinguish and select mates with similar host preferences and reject mates from the population specific to the other host tree. There is very little hybridization (only about 5 percent) between the two groups. Matings between individuals from the two populations of Rhagoletis produce hybrid flies that appear to be healthy and have normal life spans. The eggs laid by these hybrid flies, however, hatch less often than those of flies from either of the two populations. What isolating mechanism seems to be important in this hybrid population?

Reduced hybrid fertility

In the "RNA world" model for the origin of life, the first protocells (probionts) relied on RNA, not DNA, for information storage and transmission. Which of the following could best be considered evidence in support of the RNA world model?

Some RNA molecules in contemporary cells have catalytic function.

Malaria is caused by several different species of Plasmodium, a protozoan parasite. Plasmodium resistance to the common drugs used to treat malaria has increased in recent years. In a scientific study, Plasmodium samples were analyzed in blood drawn from a large number of infected patients before drug treatment and subsequently from the subset of infected patients with drug-resistant Plasmodium. DNA sequences of four different Plasmodium genes thought to be involved in resistance were compared between samples from patients with drug-sensitive Plasmodium and patients with drug-resistant Plasmodium. Which of the following best supports the hypothesis that preexisting mutations confer drug resistance?

Some of the mutations that occur most frequently in samples from patients treated with antimalarial drugs are detectable in Plasmodium samples collected prior to use of antimalarial drugs.

Over many generations, two populations of the same species can diverge into separate species through reproductive isolation. The figures below represent a model of speciation and show the results of matings between individuals from two diverging populations at four different stages of speciation. The males represented in the model are heterogametic, which means they have two different sex-determining chromosomes, XY The females are homogametic, which means they have two similar sex-determining chromosomes The offspring from each mating are labeled interpopulation hybrids. Figure 1 shows the results of a mating between a male and a female from the two populations. In each subsequent figure, the males are from one of the diverging populations and the females are from the other population. The fertility and viability of the offspring from each mating are indicated in the figures Which of the following best describes the reason for excluding hybrid males when calculating the allele frequencies of two interbreeding populations at the intermediate stage of speciation (Figure 2) ?

Sterile individuals make no genetic contribution to the next generation.

Over many generations, two populations of the same species can diverge into separate species through reproductive isolation. The figures below represent a model of speciation and show the results of matings between individuals from two diverging populations at four different stages of speciation. The males represented in the model are heterogametic, which means they have two different sex-determining chromosomes, XY The females are homogametic, which means they have two similar sex-determining chromosomes The offspring from each mating are labeled interpopulation hybrids. Figure 1 shows the results of a mating between a male and a female from the two populations. In each subsequent figure, the males are from one of the diverging populations and the females are from the other population. The fertility and viability of the offspring from each mating are indicated in the figures Using the model of speciation and applying it to a different population, which of the following outcomes is most consistent for a different species in which the males are homogametic and the females are heterogametic?

Sterility would appear in females before appearing in males.

The California newt, Taricha torosa, lives in the coastal areas around Los Angeles. Which of the following is a valid null hypothesis relating fitness to survival of a bottleneck event in a coastal area where a small, isolated population of California newts resides?

Surviving the bottleneck event will be random, so any change in the allelic frequencies of the salamander population is not attributed to

Researchers were modeling the effects of repeated cycles of isolation with occasional interbreeding among five hypothetical fish species (species A, B, C, D, and E) found in two separate lakes (lakes II and IIII) that are occasionally joined by flooding, as shown in Figure 1. The research team indicated that species A would be considered to be the single common ancestor of species B, C, D, and E. Figure 1. Current locations of populations of fish species A, B, C, D, and E Which of the following mechanisms could most likely account for the origin of species BB in Lake II?

Sympatric speciation

Rhagoletis pomonella is a parasitic fly native to North America that infests fruit trees. The female fly lays her eggs in the fruit. The larvae hatch and burrow through the developing fruit. The next year, the adult flies emerge. Prior to the European colonization of North America, the major host of Rhagoletis was a native species of hawthorn, Crataegus marshallii. The domestic apple tree, Malus domestica, is not native to North America, but was imported by European settlers in the late 1700s and early 1800s. When apple trees were first imported into North America, there was no evidence that Rhagoletis could use them as hosts. Apples set fruit earlier in the season and develop faster, where hawthorns set later and develop more slowly. Recent analysis of Rhagoletis populations has shown that two distinct populations of flies have evolved from the original ancestral population of flies that were parasitic on hawthorns. One population infests only apple trees, and the other infests only hawthorns. The life cycles of both fly populations are coordinated with those of their host trees. The flies of each population apparently can distinguish and select mates with similar host preferences and reject mates from the population specific to the other host tree. There is very little hybridization (only about 5 percent) between the two groups. Initially, which of the following isolating mechanisms is likely to have been the most important in preventing gene flow between the two populations of Rhagoletis?

Temporal isolation

Diapause is the interruption of an organism's life cycle in response to environmental cues.

The ability to enter ARD provides a strong selective advantage because reproduction can occur despite periods of food scarcity.

A current challenge for doctors involves the bacterial strain Clostridioides difficile, which no longer responds to traditional antibiotic treatments. Which of the following best explains why this particular strain of bacteria is resistant to antibiotic treatment?

The bacteria have high genetic variability and high reproductive rates.

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following procedures was most likely followed to determine the change in beak size?

The beak size in a large number of finches was measured every year from 1981 to 1987.

Blackcap birds (Sylvia atricapilla) migrate out of Germany before wintertime. Prior to the 1960s, all members of a particular blackcap population flew to Spain, which had an abundant natural food source. Now, some members of the same blackcap population fly to the United Kingdom, where food placed in feeders by humans is abundant. The blackcaps return to the same forests in Germany to nest during the breeding season. Some blackcaps that migrate to the United Kingdom have become distinguishable by certain physical and behavioral traits from blackcaps that migrate to Spain. Which of the following best predicts the effect on the blackcap population if humans in the United Kingdom continue to place food in feeders during the winter?

The blackcaps that migrate to the United Kingdom will become reproductively isolated from the blackcaps that migrate to Spain, resulting in speciation in the blackcap population.

In a hypothetical population of beetles, there is a wide variety of color, matching the range of coloration of the tree trunks on which the beetles hide from predators. The graphs below illustrate four possible changes to the beetle population as a result of a change in the environment due to pollution that darkened the tree trunks. Which of the following includes the most likely change in the coloration of the beetle population after pollution and a correct rationale for the change?

The coloration in the population shifted toward more darker-colored beetles, as in diagram IV. The lighter colored beetles were found more easily by the predators than were the darker-colored beetles.

In a hypothetical population of beetles, there is a wide variety of color, matching the range of coloration of the tree trunks on which the beetles hide from predators. The graphs below illustrate four possible changes to the beetle population as a result of a change in the environment due to pollution that darkened the tree trunks. Which of the following includes the most likely change in the coloration of the beetle population after pollution and a correct rationale for the change?

The coloration in the population shifted toward more darker-colored beetles, as in diagram IV. The lighter-colored beetles were found more easily by the predators than were the darker-colored beetles.

Commercial bananas are grown as a monoculture, with all banana plants cloned from one original banana plant. The commercial strains of bananas are seedless, so each new banana plant has to be manually planted from a cutting of an existing banana root. In the 1950s, the Gros Michel banana strain, the dominant export banana at that time, was destroyed by the fungus Fusarium oxysporum. A new Fusarium resistant variety, the Cavendish banana, was developed and is currently the banana strain grown for export. Recently, a Fusarium strain that successfully attacks the Cavendish strain has been documented. Which of the following best provides reasoning supporting a method that would help protect commercial banana crops from infection by pathogenic organisms such as Fusarium fungi?

The commercial banana strains should not be grown in monocultures, since many pathogenic organisms are able to evolve rapidly in response to a single selective pressure.

To determine the evolutionary history and relationships among organisms, scientists gather evidence from a wide variety of sources including paleontology, embryology, morphology, behavior, and molecular biology. A phylogenetic tree of vertebrates is shown. Which of the following statements is most consistent with the phylogenetic tree shown?

The common ancestor of reptiles, birds, and mammals produced amniotic eggs.

The figure shows a phylogenetic tree of various members of the order Proboscidea, which includes modern elephants. Which of the following claims is best supported by the information in the figure ?

The common ancestor of the African elephant and the mastodon is the Palaeomastodon.

Many species of corals are threatened by the increasing temperatures and decreasing pHpH of ocean waters. One species, Stylophora pistillata, has been found to thrive in water that is warmer and has a lower pHpH than the water that corals typically thrive in. Additionally, researchers have found that the tolerance for the new water conditions is heritable. Which of the following statements best explains the changes seen in S. pistillata in response to the changing water conditions?

The corals' adaptation is an example of natural selection because the tolerance is in response to a changing environment and has a genetic basis.

Some scientists claim that amphibians are currently experiencing a period of mass extinction. Which of the following should be included in an alternative hypothesis that would best support this claim?

The current extinction rate of amphibians compared with the background rate of extinction as determined by the fossil record

Female European corn borer moths (Ostrinia nubilalis) produce the sex pheromone 11−11−tetradecenyl acetate (11−TDA11−TDA), which attracts males of their species. 11−TDA11−TDA can be produced in two forms, EE and ZZ, each with a different three-dimensional shape. Researchers have discovered two different strains of the European corn borer moth living in the same area. Females of the EE strain produce primarily the EE form of 11−TDA11−TDA and females of the ZZ strain produce primarily the ZZ form of 11−TDA11−TDA. Males of both strains are more attracted to the form of 11−TDA11−TDA produced by the females of the same strain. Which of the following best predicts a long-term effect of the differences between the EE and ZZ strains?

The difference between the forms of the sex pheromone 11−TDA11−TDA produced by EE and ZZ strains will act as a prezygotic reproductive barrier leading to sympatric speciation.

Freshwater bony fish secrete large volumes of very dilute urine. Many marine bony fish secrete small volumes of concentrated urine. Which of the following best explains the differences in nitrogenous-waste excretion between freshwater and marine bony fish?

The differences arose during divergence, as fish from a common ancestor faced different selective pressures in environments of different osmolarity.

A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. The biologist discovered that from 1988 to 1993, the average beak size declined to pre-1981 levels. The reversal in beak size from 1988 to 1993 was most likely related to which of the following events?

The end of the drought

In an experiment, 100 mice were released into a field to which no other mice had access. Immediately after their release, a representative sample of mice was captured, their fur color was recorded, and they were returned to the field. After twenty years, a representative sample of mice was captured and the distribution of fur color was again recorded. Which of the following could best explain the change in fur color distribution, as shown in the table above?

The field was primarily composed of light-colored soil and little vegetation, affording gray mice protection from predators.

Two species of fish that live in extremely cold environments produce near-identical antifreeze glycoproteins, called AFGPsAFGPs. Scientists have determined the origins of the AFGPAFGP gene in both species. Selected characteristics of the two fish species are provided in Table 1. Based on the information in Table 1, which of the following statements best describes the production of nearly identical AFGPsAFGPs in these two species of fish?

The fish live in environments with similar selective pressures, and those that produce AFGPsAFGPs are better able to survive.

Ellis-van Creveld syndrome is a recessive genetic disorder that includes the characteristics of short stature and extra fingers or toes. In the general population, this syndrome occurs in approximately 1 in 150,000 live births. In a particular isolated population, however, the incidence of this syndrome among live births is 1 in 500. Assume that both the isolated population and the general population are in Hardy-Weinberg equilibrium with respect to this syndrome. Which of the following best describes the difference between the frequency of the allele that causes the syndrome in the general population and the frequency of the allele in the isolated population?

The frequency of the Ellis-van Creveld allele is 0.0447 in the isolated population and 0.0026 in the general population, which suggests that genetic drift has occurred in the isolated population.

The amino acid sequence of cytochrome c is exactly the same in humans and chimpanzees. There is a difference of 13 amino acids between the cytochrome c of humans and dogs, and a difference of 20 amino acids between the cytochrome c of humans and rattlesnakes. Which of the following statements is best supported by these data?

The human is apparently more closely related to the chimpanzee than to the dog or rattlesnake.

A small number of lizards from a mainland population have been deposited on four isolated islands because of the effects of a rare strong storm. Which of the following best predicts the outcome of these lizards reproducing for many generations on the islands?

The isolation prevents gene flow; thus, the lizards on different islands experience prezygotic isolation.

Modern bananas originated from a cross between a tetraploid banana species and a diploid banana species. The product of this cross was the triploid Cavendish banana strain, a sterile hybrid that is only grown asexually. Recently, the Panama fungus has been observed more frequently parasitizing the Cavendish banana, and scientists claim that this type of banana is on the brink of extinction. Which of the following provides the best explanation of the scientists' claim regarding the threat to the Cavendish banana?

The lack of genetic diversity of the Cavendish banana decreases the chance that a variation exists in the population that is immune to the fungus.

By discharging electric sparks into a laboratory chamber atmosphere that consisted of water vapor, hydrogen gas, methane, and ammonia, Stanley Miller obtained data that showed that a number of organic molecules, including many amino acids, could be synthesized. Miller was attempting to model early Earth conditions as understood in the 1950s. The results of Miller's experiments best support which of the following hypotheses?

The molecules essential to life today could have formed under early Earth conditions.

Two groups of students attempted to re-create the primitive atmospheric conditions of early Earth using the apparatus represented below. Each group ran the experiment with different gas mixtures in the apparatus. Which of the following statements best justifies the claim that the conditions in at least one of the experiments could generate the molecular building blocks essential for life?

The nitrogen N2 gas and ammonia NH3 gas in experiment 1 could provide the elemental nitrogen required for the formation of amino acids.

In a large, isolated population of an insect species, a specific gene locus has one dominant allele (A)(A) and one recessive allele (a)(a). The genotype frequencies of the gene were collected for ten generations, as shown in Table 1. Which of the following could best account for the change in genotypic frequencies over the ten generations?

The population is not exhibiting random mating between individuals.

All of the following are examples of prezygotic genetic isolating mechanisms EXCEPT:

The progeny of a cross between two different lizard species fail to develop properly.

Undersea landslides can disrupt marine habitats by burying organisms that live on the ocean floor. The graph above shows the size of a population of a certain organism that lives on the ocean floor. The population was affected by a recent landslide at the time indicated on the graph. Which of the following best predicts how the population will be affected by the landslide?

The reduced population will likely have allelic frequencies that are different from the initial population.

Sugar gliders and Northern flying squirrels are mammals that have many morphological similarities despite being genetically different. Both are nocturnal and have large eyes to help them see in the dark. Both live in trees and have flaps of skin connecting their front and back legs, and when their front and back legs are extended, the flaps allow the animals to glide from one tree branch to another. Sugar gliders are native to Australia, and Northern flying squirrels are native to North America. Which of the following best explains the morphological similarities between these two species?

The similarities between the species evolved independently as a result of similar selective pressures in each species' environment.

Which of the following pieces of evidence best supports the hypothesis that birds and crocodilians (crocodiles and alligators) are more closely related to each other than they are to other organisms?

The skulls of birds and crocodilians have an opening that is absent in the skulls of other reptiles.

Two populations of a species of squirrel are geographically isolated from each other. Although they have the same population density, one population is significantly larger in number than the other. A new bacterial disease, which is easily spread and extremely virulent, affects both populations at the same time. Which of the following is the best prediction of how the new disease will affect the two populations?

The smaller population will be more affected than will the larger population, because the smaller population has less genetic variation than the larger population has.

Many scientists claim that the synthesis of the first organic molecules from inorganic precursors was possible because of the highly reducing atmosphere found on primitive Earth. Which of the following is an appropriate null hypothesis that could be used when investigating the claim?

The synthesis of organic molecules from inorganic molecules is possible under current atmospheric oxygen levels as well as those found on primitive Earth.

Dr. Robert Hazen has worked to develop a hypothesis that explains the origin of life on Earth. His work has focused on hydrothermal vents, which are cracks in the ocean floor. Water heated by molten rock beneath the crust escapes from these vents at very high temperatures, producing hot, high‑pressure environments at the vents on the ocean floor. In order to provide evidence that these vents may be areas where life originated, which of the following states a null hypothesis Hazen might have used to begin his research?

The temperatures and pressures found in hydrothermal vents resemble conditions described in currently accepted origins of life hypotheses.

Goats and sheep belong to the same family but different genera. While they often live together in the same pastures, the hybrid offspring that are occasionally produced between the two species rarely survive. When such a hybrid does survive, it is usually sterile. Which of the following best explains the mechanism that maintains reproductive isolation between goats and sheep?

The two species have a different number of chromosomes, resulting in a postzygotic barrier.

Researchers investigated the habitat preferences of two species of garter snakes, Thamnophis sirtalis and Thamnophis atratus. To create a choice chamber, the researchers built a meshed enclosure and positioned one end of the enclosure at the edge of a small pond. Zone I of the enclosure was located in the water, whereas zone IV of the enclosure was located 2-3 meters away from the water, as represented in the figure below. Snakes inside the enclosure were able to move freely between zones. In a series of experiments, the researchers introduced a single snake into zone IV of the enclosure at 7:00 A.M. The researchers recorded the location of the snake at six time points throughout the day. In a related experiment, the researchers introduced two snakes, one of each species, into the enclosure at the same time and observed the location of each of the two snakes at the same six time points as before. The researchers repeated both the one-snake and two-snake experiments using different individual snakes of each species. The results are presented in the table. Both species of garter snakes prey on the California newt, Taricha torosa, a small amphibian that produces a potent neurotoxin (TTX) in its skin. However, neither species of garter snake is affected by TTX. The resistance to TTX is associated with mutations in the SCN4A gene. Which of the following best supports a claim that TTX resistance arose independently in T. atratus and T. sirtalis ?

The two species of snakes have different genetic mutations in the SCN4A gene.

In humans, one allele of the APOEAPOE gene, called APOE-ε2APOE-ε2, can result in a high tolerance of cholesterol. Cholesterol is a vital substance for humans but may lead to heart disease in an older adult with a history of high cholesterol diets. High cholesterol diets are becoming more prevalent in the United States. Currently only about 2% of humans carry the APOE-ε2APOE-ε2 allele. Which of the following states a valid null hypothesis about the future distribution of APOEAPOE alleles in future generations in the United States?

The variant protects an individual from a condition that is only common among humans beyond reproductive age, so the frequency of the allele will likely not change much in the future because it is not influenced by natural selection.

For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law. Unlike most natural populations, this population is best characterized in which of the following ways?

There is genetic equilibrium.

Scientists want to determine whether the rapid economic growth in China between 1950 and 2000 caused a mass extinction of animal species during that time period. A mass extinction event is considered to occur when the rate of species extinction far exceeds the background extinction rate. The scientists collected data on the number of extinctions of selected vertebrate species in China between 1950 and 2000, as shown in Table 1. Extinction rates were ascertained by measuring the average percent of species lost (PSL)(PSL). Which of the following is the null hypothesis most relevant for evaluating the data in Table 1 ?

There is no significant difference between the extinction rate of animals between 1950 and 2000 in China and the background extinction rate.

Which of the following observations would provide the strongest evidence that two plants belong to different biological species?

They produce viable but sterile offspring.

Hemoglobin is a highly conserved protein used by all mammals to transport oxygen. Table 1 was constructed by comparing the amino acid sequence in the hemoglobin molecules from five different mammal species. Which of the following best describes the importance of the number of amino acid differences indicated in Table 1 ?

They reflect the number of base pair changes in the DNADNA.

MRSA is the acronym for methicillin-resistant Staphylococcus aureus. Many of the strains of the common bacterium are also resistant to other antibiotics in use today. The resistance is linked to a collection of genes carried on plasmids that are passed from one bacterium to another by conjugation. Suppose a newly discovered, chemically different antibiotic is used in place of methicillin. Which of the following would be the most likely effect on Staphylococcus aureus antibiotic resistance?

Transmission of the methicillin-resistance plasmid would gradually decrease but the plasmid would not entirely disappear from the Staphylococcus aureus population.

The FtsZ protein is present in prokaryotes and in chloroplasts. The protein is structurally and functionally similar to tubulin proteins of eukaryotic cells. Which of the following is a likely conclusion to draw from this information?

Tubulin genes are evolutionarily derived from the gene that codes for the FtsZ protein.

Which of the following statements best explains how a condition of Hardy-Weinberg equilibrium results in a population that exhibits stable allele frequencies (i.e., a nonevolving population) ?

Without migration or mutation, new alleles cannot be introduced to the population.

Data regarding the presence (+) or absence (-) of five derived traits in several different species are shown in the table below. Which of the following cladograms provides the simplest and most accurate representation of the data in the table?

Y W V Z X

All of the following were likely present on the primitive Earth during the evolution of self-replicating molecules EXCEPT

an O2-rich atmosphere

In plants, members of the euphorbia family and the cactus family have separate origins, with the euphorbia evolving in the desert regions of Asia and Africa and the cacti in the desert regions of the Americas. Both have fleshy stems adapted for water storage, protective spines, and leaves that are greatly reduced or absent. The similarities between these two families of plants represent an example of

convergent evolution

Ascorbic acid (vitamin C) is an organic molecule necessary for the health of plants and animals. The majority of animals, including most mammals, synthesize ascorbic acid from organic precursors, but some primates are unable to synthesize ascorbic acid and must instead acquire it from dietary sources, such as certain fruits and vegetables. The L-gulonolactone oxidase (GULO) gene encodes an enzyme that catalyzes a required step in the biosynthesis of ascorbic acid. Most mammals carry a functional copy of the GULO gene, but some primates carry only a GULO pseudogene, which is a nonfunctional variant. A comparison of GULO genes and GULO pseudogenes from different animals can provide insight into the evolutionary relatedness of the animals. In Table I, selected members of some mammalian groups are listed, along with an indication of their ability to synthesize ascorbic acid. Table II shows an alignment of amino acid coding sequences from homologous regions of the GULO genes and GULO pseudogenes of the organisms listed in Table I. Figure 1 represents the universal genetic code. Which of the following phylogenetic trees best illustrates (with the X) the point at which the mutation in the GULO gene most likely occurred during the evolutionary history of these organisms?

cutoff infront of human chimpanzee and oragutan

In a small group of people living in a remote area, there is a high incidence of "blue skin", a condition that results from a variation in the structure of hemoglobin. All of the "blue-skinned" residents can trace their ancestry to one couple, who were among the original settlers of this region. The unusually high frequency of "blue skin" in the area is an example of

genetic drift

In Darwinian terms, the fittest individuals of a species are those that

leave the greatest number of reproducing descendants

More than 90 percent of the nitrogenous waste that is processed and excreted by humans is derived from the breakdown of proteins. Most of the remaining nitrogenous waste material is derived from the breakdown of

nucleic acids

For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law. If p equals the frequency of the dominant allele and q equals the frequency of the recessive allele, which of the following terms represents the frequency of the individuals who show the dominant phenotype?

p^2 + 2pq

The fossil record indicates that in some cases reasonably well-defined species appear suddenly and remain unchanged for a long time before they become extinct. This phenomenon is referred to as

punctuated equilibrium

The condition in which there are barriers to successful interbreeding between individuals of different species in the same community is referred to as

reproductive isolation

The placement and development of two bones of the reptilian jaw are very similar to that of two bones of the mammalian middle ear, which probably evolved from the reptile bones. The similarity of these bones is an example of

structural homology

The appearance of a fertile, polyploid individual within a population of diploid organisms is a possible source of a new species. If this individual is capable of reproducing to form a new population, scientists would consider this to be an example of

sympatric speciation

Rhagoletis pomonella is a parasitic fly native to North America that infests fruit trees. The female fly lays her eggs in the fruit. The larvae hatch and burrow through the developing fruit. The next year, the adult flies emerge. Prior to the European colonization of North America, the major host of Rhagoletis was a native species of hawthorn, Crataegus marshallii. The domestic apple tree, Malus domestica, is not native to North America, but was imported by European settlers in the late 1700s and early 1800s. When apple trees were first imported into North America, there was no evidence that Rhagoletis could use them as hosts. Apples set fruit earlier in the season and develop faster, where hawthorns set later and develop more slowly. Recent analysis of Rhagoletis populations has shown that two distinct populations of flies have evolved from the original ancestral population of flies that were parasitic on hawthorns. One population infests only apple trees, and the other infests only hawthorns. The life cycles of both fly populations are coordinated with those of their host trees. The flies of each population apparently can distinguish and select mates with similar host preferences and reject mates from the population specific to the other host tree. There is very little hybridization (only about 5 percent) between the two groups. The divergence between the two populations of Rhagoletis must have occurred very rapidly because

the apple tree was imported into North America with European settlement approximately 200 years ago

For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law. What is the frequency of the recessive allele?

√0.25