AP Biology Unit 7 Test

The researchers built an enclosure to prevent migration into and out of the O'Neill rock pocket mouse population for a period of two years. Which of the following best predicts the effect of the enclosure on the O'Neill population? Select one: a. The frequency of the MC1RD allele will decline due to natural selection. b. The O'Neill population will rapidly evolve into a separate species. c. One of the alleles for the MC1R gene will become fixed due to genetic drift. d. The O'Neill population will become less diverse due to the bottleneck effect.

a. The frequency of the MC1RD allele will decline due to natural selection.

In addition to the ABO blood groups, humans have an MN blood type system in which the M and N alleles are codominant to one another. A group of scientists found that in one population the frequency of the M allele was 0.82, and the frequency of the N allele was 0.18. Assuming that the population is in Hardy‑Weinberg equilibrium, which of the following is the expected frequency of individuals with the genotype MN? Select one: a. 0.672 b. 0.148 c. 0.295 d. 0.640

c. 0.295

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) ? Select one: a. In the absence of selection, allele frequencies in a population will not change. b. Large populations are not subject to natural selection. c. Without migration or mutation, new alleles cannot be introduced to the population. d. Random mating prevents gene flow from changing allele frequencies.

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

Based on the data in Table 1, which of the following best describes the relationship between the MC1R gene and coat color in the Carrizozo, New Mexico, rock pocket mouse population? Select one: a. The MC1RD allele is absent from the Carrizozo population, so all the mice in this population must have coats that are light in color. b. The MC1RD allele is absent from the Carrizozo population because of different environmental pressures in the Carrizozo population. c. The MC1RD allele is responsible for dark coat color in the Carrizozo population and likely spread from the Arizona population through migration. d. The MC1RD allele is not responsible for dark coat color in the Carrizozo population, so the dark coat color is likely a result of convergent evolution.

d. The MC1RD allele is not responsible for dark coat color in the Carrizozo population, so the dark coat color is likely a result of convergent evolution.

Some plant species flower in response to increasing daily temperatures in the spring. Many of these species rely on pollinators that migrate based on changes in day length and the position of the Sun. The current global warming trend is placing new selective pressures on the species involved in these relationships. Which of the following best explains the impact of these new selective pressures on the organisms involved? Select one: a. If the environment for the plant species becomes too warm, the pollinators will no longer migrate to that area in the spring, continuing on to a more northern environment instead. b. Migrating pollinators will start migrating later in the year, switching from spring-flowering plants to summer-flowering plants. c. The warmer temperatures will lead to a drier environment, so the plants will no longer produce enough nectar to attract the pollinators. d. The plant species will flower earlier in the spring in response to rising temperatures before the arrival of the pollinators, so seeds will not be produced.

d. The plant species will flower earlier in the spring in response to rising temperatures before the arrival of the pollinators, so seeds will not be produced.

In a large, isolated population of an insect species, a specific gene locus has one dominant allele (A) and one recessive allele (a). The genotype frequencies of the gene were collected for ten generations, as shown in Table 1. Table 1. Genotypic frequencies over ten generations in an insect species AA Aa aa Generation 1: 0.47 0.43 0.10 Generation 5: 0.32 0.60 0.08 Generation 10: 0.20 0.75 0.05 Which of the following could best account for the change in genotypic frequencies over the ten generations? Select one: a. The population is in Hardy-Weinberg equilibrium, which allows for changes in genotypic frequencies every generation. b. Because the A allele is unstable, over the course of the study most of the A alleles mutated to become a alleles. c. The population is becoming extinct because the a allele is disappearing. d. The population is not exhibiting random mating between individuals.

d. The population is not exhibiting random mating between individuals.

Which of the following is closest to the frequency of the MC1RD allele in the Tule Mountain population? Select one: a. 0.03 b. 0.06 c. 0.97 d. 0.94

a. 0.03

Because cheetahs, Acinonyx jubatus, experienced a bottleneck event about ten thousand years ago, living cheetahs exhibit very little genetic variation compared to other living species of large cats. Which of the following principles best justifies a claim that cheetahs, compared to other large cats, have a relatively low resilience to environmental perturbations? Select one: a. Populations with little genetic diversity are less likely to contain individuals that can withstand different selective pressures. b. Populations with low genetic diversity are more likely to contain individuals that can withstand different selective pressures. c. A captive population of cheetahs kept in a confined area will have a greater risk of contracting and passing on a virus. d. When a population is reduced, new niches become available in the environment, which can trigger adaptive radiation.

a. Populations with little genetic diversity are less likely to contain individuals that can withstand different selective pressures.

In a particular region, a species of lizard lives in the lowlands. Even though there are numerous mountains in the region, the climate on the mountains is too cold for the lizards to survive. Scientists are concerned that the lowlands will become much warmer by the end of the twenty-first century and will become unsuitable for this lowland lizard species. Which of the following best predicts the impact on the lizard species if there is a gradual increase in the average temperatures found in both the lowlands and mountains in this region? Select one: a. Some lizards will migrate to new habitats in the mountains and become isolated, leading to allopatric speciation. b. The lizards will hybridize with a different lizard species that is adapted to a warmer environment, leading to increased genetic variation in the species. c. The species will undergo artificial selection, as the genes will adapt to warmer temperatures. d. The species will experience a genetic bottleneck, and sympatric speciation will result in the development of several new species.

a. Some lizards will migrate to new habitats in the mountains and become isolated, leading to allopatric speciation.

Figure 2. Map of the island following the 1852 earthquake The island was surveyed again in 2015, and scientists determined that the giant kangaroo rats originally in population A are now to be considered as a new species. Which of the following best explains the mechanism that caused this speciation event in the giant kangaroo rats of population A? Select one: a. The animals in population A were reproductively isolated from those in populations B, C, and D. b. The animals in population A mate at different times of year, causing their gametes to be incompatible with those from animals in populations B, C, and D. c. The animals in population A were exposed to different predators and had to modify their fur color to be better camouflaged. d. The animals in population A accumulated fewer genetic mutations, adapting to their microclimate.

a. The animals in population A were reproductively isolated from those in populations B, C, and D.

In eastern gray squirrels, Sciurus carolinensis, the allele for black fur (B) is dominant to the allele for gray fur (b). In a particular population of gray squirrels, 64% have black fur and 36% have gray fur. A researcher calculated the allelic frequencies to be B=0.4 and b=0.6. Five years later, the researcher returned to the location and determined the allelic frequencies within the squirrel population to be B=0.6B and b=0.4b. Which of the following could best explain the increase in the frequency of the B allele in the population after five years? Select one: a. The frequency of the B allele increased due to the selective pressures of the environment. b. The frequency of the B allele increased because it is the dominant allele. c. The frequency of the B allele increased because black squirrels randomly mate with other eastern gray squirrels. d. The frequency of the B allele increased because squirrels with gray fur exhibited greater fitness.

a. The frequency of the B allele increased due to the selective pressures of the environment.

A scientist is studying the impact of mutagens on genetic variation in mice. In an experiment, the scientist creates two groups of twenty highly inbred mice. Because the mice are highly inbred, they are essentially identical to one another. One group is given food with an added substance that is known to be a mutagen. The second group is fed the same food without the mutagen. After several generations, both groups of mice are given a new type of food that is harder to digest than the previous food. After rearing five additional generations of the mice on this new food, the two groups are assessed for how efficiently this new food is digested. Which of the following is the most reasonable prediction about the results of the experiment? Select one: a. The group of mice fed the mutagen will show a greater ability to digest the food, because the higher genetic variation within the group makes it more likely that some individuals will have a combination of genes better adapted to the new food. b. Neither group of mice will show any change in the ability to digest the food because thousands of years are required to develop such a change. c. The group fed the mutagen will show a decrease in the ability to digest the new food, because the mutagen prevented natural selection from acting on them. d. Both groups of mice will show an increase in the ability to digest the new food, because they experienced the same selective pressures.

a. The group of mice fed the mutagen will show a greater ability to digest the food, because the higher genetic variation within the group makes it more likely that some individuals will have a combination of genes better adapted to the new food.

A scientist maintains a large population of the fruit fly Drosophila affinis in the laboratory. After 20 generations of allowing this population of about 1000 flies to mate randomly, 10 females and 10 males were isolated from the rest of the population. Both the larger population and the isolated population were maintained under identical conditions and allowed to mate randomly for another 20 generations. After the 20 generations, DNA sequencing was used to determine the genetic composition of each population. Which of the following predicts the expected outcome of the experiment? Select one: a. The two populations will show significant genetic differences because the founder effect will result in significant losses in diversity in the smaller population. b. The two populations will show significant genetic differences because there will be much higher rates of mutation in the smaller population. c. The two populations will not show any differences because they were reared under identical conditions. d. The two populations will not show any differences because they originated from the same gene pool.

a. The two populations will show significant genetic differences because the founder effect will result in significant losses in diversity in the smaller population.

Humans vary in their ability to taste the bitter chemical compound phenylthiocarbamide (PTC). The taster phenotype is dominant to the nontaster phenotype. Researchers tested the PTC taster phenotype of individuals from an isolated population. In the sample, 780 individuals were able to taste PTC and 70 individuals were not able to taste PTC. Assuming the population is in Hardy-Weinberg equilibrium, what is the frequency of the non-taster allele? Select one: a. 0.71 b. 0.29 c. 0.08 d. 0.41

b. 0.29

Owls (primary predators of rock pocket mice) are nocturnal visual predators that are able to distinguish effectively between dark and light colors in low-light conditions. Which of the following best explains the relationship between coat color and predation rate in the rock pocket mouse population on the lava flow rocks with respect to the different coat color phenotypes? Select one: a. A light coat color reflects more light and therefore mice with light coats have a lower predation rate. b. A dark coat color provides camouflage to mice on the lava flow rocks; therefore, mice with dark coats have a lower predation rate in that habitat. c. At night, predators have reduced vision, so there is no relationship between coat color and predation rate on rock pocket mice. d. A dark coat color reflects less light and therefore mice with dark coats have a lower predation rate.

b. A dark coat color provides camouflage to mice on the lava flow rocks; therefore, mice with dark coats have a lower predation rate in that habitat.

Which of the following best describes the processes occurring between the mouse populations and their environments? Select one: a. Natural selection favors the mice with the dark coat color, causing the mice in all of the populations to be better adapted. b. Dark color is selected for in mice from the West, Mid, and East populations. c. Light color is selected for in mice from the West, Mid, and East populations. d. Natural selection favors the mice with the light coat color, causing the mice in all of the populations to be better adapted.

b. Dark color is selected for in mice from the West, Mid, and East populations.

Which of the following best illustrates the change in the frequencies of the A and a alleles from generation 1 to generation 2 and to future generations, assuming Hardy-Weinberg equilibrium is present after generation 1? Select one: a. Future generations will eventually completely lose the a allele from the gene pool. There will not be any new individuals with the aa genotype. Generation 1 Generation 2 Generation n AA .67 .87 1.0 aa .33 .13 0 b. Future generations will have the same frequencies of the A and a alleles as generation 2. Individuals with the aa genotype could be produced. Generation 1 Generation 2 Generation n AA .67 .87 .87 aa .33 .13 .13 c. Future generations will completely lose the a allele from the gene pool. There will no longer be individuals with the aa genotype. Generation 1 Generation 2 Generation n AA .73 1.0 1.0 aa .27 0 0 d. Future generations will have fewer a alleles in the gene pool but will not completely lose the allele. There will be a few individuals with the aa genotype. Generation 1 Generation 2 Generation n AA .73 .87 .95 aa .27 .13 .05

b. Future generations will have the same frequencies of the A and a alleles as generation 2. Individuals with the aa genotype could be produced. Generation 1 Generation 2 Generation n AA .67 .87 .87 aa .33 .13 .13

To prevent the loss of genes as chromosome ends wear down during DNA replication, the tips of eukaryotic chromosomes have specialized DNA "caps" called telomeres. Telomeres consist of hundreds or thousands of repeats of the same short DNA sequence, which varies between organisms. The telomeric repeat sequences for selected organisms are given in Table 1. Table 1. Telomeric Repeat Sequences for Selected Organisms Organism Telomeric Repeat Sequence (5′ to 3′) Human TTAGGG Mouse TTAGGG Paramecium TTGGGT Green alga TTTTAGGG Onion CTCGGTTATGGG Which of the following best predicts why humans and mice have identical telomeric repeat sequences? Select one: a. Mice utilized the 5′-TTAGGG-3′ telomeric repeat sequence first, but the sequence independently evolved in humans as well. b. Humans and mice share a recent common ancestor that had the 5′-TTAGGG-3′ repeat sequence in its telomeres. c. Humans and mice have the same number of chromosomes. d. Humans and mice have the same number of genes.

b. Humans and mice share a recent common ancestor that had the 5′-TTAGGG-3′ repeat sequence in its telomeres.

The researchers determined that the East lava flow population is not in Hardy-Weinberg equilibrium. Which of the following best explains why the population is not in Hardy-Weinberg equilibrium? Select one: a. The presence of heterozygotes for the MC1R gene in the East lava flow population indicates that mating is occurring randomly between mice with different coat colors. b. The presence of MC1Rd alleles in the East lava flow population is an indication of gene flow from mice populations living on light granite rocks. c. The selective pressures on the East lava flow population are not strong enough to maintain Hardy-Weinberg equilibrium. d. The East lava flow population does not experience migration, which is a required condition for Hardy-Weinberg equilibrium.

b. The presence of MC1Rd alleles in the East lava flow population is an indication of gene flow from mice populations living on light granite rocks.

Which of the following rows of data listed in table 1 best supports the possibility of a common ancestor for the organisms listed there? Select one: a. Flagellated sperm cells b. Seeds enclosed in fruit c. Cell wall composed of cellulose d. Vascular tissue

c. Cell wall composed of cellulose

Figure 1. Effectiveness of Insecticides #1 and #2 Of the following, which is the best next step for the researchers to best determine the long-term effectiveness of these insecticides with regards to the development of resistance? Select one: a. Spray these insecticides on a different species of insect (whose genotypes are also known) to determine its effectiveness on insects that are not pests. b. Set up a new experiment in which these insects are sprayed with two different insecticides to see if they are more effective than Insecticides #1 and #2. c. Continue treating the three insect populations with the same insecticides and determine whether their efficiencies decline significantly after several generations. d. Add an additional treatment group to the experiment to measure the effectiveness of another insecticide (Insecticide #3) over several generations.

c. Continue treating the three insect populations with the same insecticides and determine whether their efficiencies decline significantly after several generations.

Human activities can drive changes in ecosystems that affect the risk of extinction. An experiment is designed to help prevent the further decline and extinction of the Henslow's sparrow in which controlled burns will be set in the each of the ten Midwest counties in order to prevent the regrowth of the forest. Which of the following represents an alternate hypothesis tested by this experiment with regard to the population sizes of Henslow's sparrows? Select one: a. There will be no difference in the populations observed in the controlled fire sites and the rest of counties 5 and 6. b. Controlled fires in counties 6 and 8 will have no effect on the sparrow populations. c. Controlled fires in counties 4 and 5 will lead to an increase in the sparrow population. d. Population numbers will continue to decline even in the controlled fire sites because human activities always lead to extinction.

c. Controlled fires in counties 4 and 5 will lead to an increase in the sparrow population.

Some researchers claim that the decrease in plant species richness of this woodlot is unrelated to human activities over the last forty years. Which of the following would be an appropriate alternative hypothesis? Select one: a. The woodlot is shaded, with little direct sunlight, and species 3, 4, and 5 are shade-intolerant canopy trees. b. The woodlot environment is arid and species 1 and 2 are well-adapted to conserve water. c. During the last few decades, tall buildings have been built around the woodlot, and species 3, 4, and 5 are shade‑intolerant plants d. Interspecific competition caused the extinction of species 4 and 5.

c. During the last few decades, tall buildings have been built around the woodlot, and species 3, 4, and 5 are shade‑intolerant plants

Geologic events such as mountain building can directly affect biodiversity. The Sino‑Himalayan fern, Lepisorus clathratus is widely distributed on the Qinghai‑Tibetan plateau. If geologic events lead to a series of new mountain ranges that divide the plateau into several discrete valleys, which of the following best describes how the L. clathratus population would be affected? Select one: a. Gene flow will be reduced by sexual selection and polyploidy. b. Chance events will cause allele frequencies to fluctuate unpredictably from one generation to the next. c. Geographic isolation will create separate gene pools, leading to speciation over time. d. Ferns reproduce asexually, so there will be no impact on the gene pool of the species.

c. Geographic isolation will create separate gene pools, leading to speciation over time.

A group of researchers noticed that using a particular drug to treat cancer in mice would reduce the size of the tumor, but some of the tumor cells appeared to be resistant to the drug since some of these cells would increase in number over time. The researchers wish to increase the reliability of their experimental observations before investigating new claims that chemotherapy-resistant tumors are an example of continuing evolution. Of the following, which is the best next step the researchers might take to increase the reliability of their evidence? Select one: a. Isolating resistant tumor cells and looking for novel mutations in proto-oncogenes b. Increasing the dose of chemotherapy being administered to the mice c. Increasing the number of trials and the number of mice in each treatment group d. Plotting the tumor volume data as a graph rather than as a table

c. Increasing the number of trials and the number of mice in each treatment group

There are two species of elephant seals: northern elephant seals, Mirounga angustirostris, found off the western coast of North America from Baja California to the Gulf of Alaska, and southern elephant seals, M. leonina, found in the southern oceans. Hunting in the nineteenth century has been blamed for a drastic reduction in the northern elephant seal population. Even though the population has rebounded following restrictions on seal hunting, genetic variation is greatly reduced in the northern species compared to that in the southern species. Which of the following conditions of Hardy-Weinberg equilibrium was most likely not met in the northern elephant seal population following overhunting? Select one: a. Random mating b. No new mutations c. Large population size d. Absence of selection

c. Large population size

In a certain small mammal, fur color is controlled by a pair of alleles, with B being dominant over b. The genotypes BB and Bb result in dark-colored fur, the genotype bb results in light-colored fur. A population of the species has the following allele frequencies: B=0.85 and b=0.15. If a fire caused the surface of the ground in the habitat of the species to become darker in color, which of the following claims about the impact on the allele frequencies in this population is most reasonable? Select one: a. The frequency of homozygous recessive individuals will increase because light-colored fur absorbs less heat. b. The frequency of the b allele will increase because there will be more heterozygous individuals. c. The frequency of the B allele will increase because light-colored individuals will be more visible to predators. d. The frequency of both alleles will increase because the population will enter a period of rapid growth.

c. The frequency of the B allele will increase because light-colored individuals will be more visible to predators.

A famous study from the nineteenth century involves the peppered moth, Biston betularia, commonly found in Great Britain and Ireland. At that time, the moths, normally white with black speckles, known as the peppered variety, became less common than the solid black variety. The population was predominantly black throughout the nineteenth century. By the end of the twentieth century, the peppered version of the moth was again more common than the black version. Which of the following best explains the phenotypic pattern in the moths over time? Select one: a. The frequencies of the different phenotypes in the moth population changed randomly due to genetic drift. b. During the nineteenth century, increased ship commerce between Great Britain and Ireland facilitated the gene flow of the black variety, spreading it throughout the moth's normal range. The switch to increased transport by planes during the twentieth century reduced this gene flow. c. The increased air pollution of the nineteenth century due to the use of coal led to a darkening of surfaces from soot. The darker backgrounds conferred a selective advantage to the black variety, as described by natural selection. A shift to less polluting fuel in the twentieth led to cleaner air and a lightening of the moth's normal habitat. d. The black variety was a nineteenth century mutation, dominant to the peppered variety. The allele for the peppered trait, being recessive, decreased in frequency. However, an additional mutation in the black allele changed it from a dominant to a recessive allele at the turn of the twentieth century, leading to a return to the dominance of the original peppered variety.

c. The increased air pollution of the nineteenth century due to the use of coal led to a darkening of surfaces from soot. The darker backgrounds conferred a selective advantage to the black variety, as described by natural selection. A shift to less polluting fuel in the twentieth led to cleaner air and a lightening of the moth's normal habitat.

Figure 1. Best-fit curve for winning times in the Kentucky Derby since 1880 Which of the following best explains the trend shown in Figure 1? Select one: a. The distance the horses ran became shorter between 1880 and 1940. b. After 1940, natural selection prevented any additional speed increases. c. All of the selective breeding programs ended in 1940. d. By 1940, most genetic variation for speed had been lost from the gene pool.

d. By 1940, most genetic variation for speed had been lost from the gene pool.

Figure 1. The frequency of M and N alleles in selected populations Based on the data in Figure 1, which of the following would most affect the allelic frequencies of the populations on Isabela and Butuan? Select one: a. Migration of individuals between the Isabela and Butuan populations b. Increased population sizes over time in the Isabela population, but no change in the Butuan population c. Random mating within each population d. Immigration of individuals from Metro Manila into the two populations

d. Immigration of individuals from Metro Manila into the two populations

Mollusk fossils were excavated and collected from a coastal cliff. Scientists studying the fossils observed patterns of changing shell shape in the mollusks. The scientists identified a period of stability or stasis, followed by rapid change, and then stasis again with regard to shell shape. Which of the following statements best predicts the result of a comparison between the fossils found before and after the period of rapid change? Select one: a. Most of the species found in the second static period will resemble each other more than the species found in the first static period. b. The same species will be found in both static periods, but the species in the second static period will have smaller shells due to the stress of undergoing rapid change. c. The same species will be found in both static periods, but they will have different shell shapes. d. Most of the species found in the first static period will be absent in the second static period.

d. Most of the species found in the first static period will be absent in the second static period.

Students created a model showing one possible mechanism for speciation in which a geographic barrier separated one large population into two smaller populations, A and B. Over time, populations A and B developed into two distinct species. The model is shown in Figure 1. Figure 1. Model of speciation Which of the following best describes what occurred during the periods indicated by the arrows? Select one: a. In response to different environments, populations A and B experienced different mutation rates, leading to the emergence of two different gene pools and, over time, new species A and B. b. Gene flow between populations A and B maintained sufficient variation in both gene pools to facilitate the development of two distinct species. c. Population B was separated for a longer time from the original population than population A was, and population B evolved into a more distinct new species than population A did. d. Natural selection acted on variation that was present in both populations A and B, and the lack of gene flow eventually led to the formation of two new species.

d. Natural selection acted on variation that was present in both populations A and B, and the lack of gene flow eventually led to the formation of two new species.