AP Bio Unit 7

Nine percent of a population is homozygous recessive (aa) at a certain locus. Assuming that the population is in Hardy-Weinberg equilibrium, which of the following is closest to the frequency of the recessive allele (a) ?

0.30

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 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

In a sample of 2,400 people, 1,482 were found to have the dominant (taster) phenotype. Assuming that the population is in Hardy-Weinberg equilibrium, approximately how many individuals in the sample are expected to be heterozygous for TAS2R38?

1,133

If all insectivorous birds and remaining beetles were removed from habitat 2 and 500 additional dark-brown beetles and 500 additional light-tan beetles were then released into habitat 2, which of the following is the best estimate of the number of additional dark-brown beetles that would be expected to be recaptured in habitat 2 after one more week?

120

The gene encoding the catalytic subunit of cytochrome c oxidase (MT-CO1) is found in the mitochondria of all animals. The gene evolves rapidly and is often used to determine evolutionary relationships among species. Table 1 shows DNA sequence differences among four animal species (II, IIII, IIIIII, and IVIV). Which of the following cladograms best represents the evolutionary relationships among the four species?

2 1 3 4

Which of the following phylogenetic trees is most consistent with the data?

3 4 2 1 5

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%

In a certain flock of sheep, 4 percent of the population has black wool and 96 percent has white wool. Assume that the population is in Hardy-Weinberg equilibrium. What percentage of the population is homozygous for white wool?

64%

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

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.

The table above shows the types and properties of nitrogencontaining wastes produced by several vertebrates. Which of the following is the best evolutionary explanation of the data?

Ammonia secretion requires a large volume of water and was therefore selected against in terrestrial vertebrates.

Retinitis pigmentosa is a rare genetic disorder that causes the breakdown of cells in the eye, resulting in vision loss. Worldwide, the occurrence of retinitis pigmentosa in the population is approximately 11 in 4,0004,000. However, on a small group of islands in the Atlantic Ocean, the occurrence is approximately 11 in 5858. Which of the following best explains how the occurrence of a rare, genetic disorder can be so much more prevalent on a small group of islands as compared with the rest of the world?

An unusually high number of individuals with the disease initially colonized the islands, and there has been little immigration to the islands since that time.

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.

Cods and icefish are the only orders of fish that include species that produce antifreeze proteins in their blood. Based on the cladogram in Figure 1, which of the following scenarios describes the most likely evolutionary history of antifreeze protein synthesis in fish?

Antifreeze proteins arose twice, once in the cod lineage and once in the icefish lineage.

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 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

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?

Which of the following best predicts how phylogenetic relationships might be revised if transposon 1 was not found in chimpanzees?

Chimpanzees would be more closely related to humans than to bonobos.

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.

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

Lobe-finned fishes were present in the oceans of the world approximately 400 million years ago. The first tetrapods (vertebrates that had limbs and could move on land) date to about 365 million years ago. One hypothesis states that early tetrapods evolved from lobe-finned fishes. Which of the following is the best plan for testing the hypothesis?

Comparing the arrangements of bones in the fins of lobe-finned fishes and limbs of the earliest tetrapods

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.

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.

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?

Researchers investigating two populations of the same species recorded the elevation at which individuals from each population were found (Figure 1). Which of the following claims is best supported by the data in Figure 1 ?

Gene flow is unlikely to occur between the two populations because they are geographically isolated.

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.

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?

Which of the following scientific questions will best help researchers determine when the nontaster allele arose in the evolutionary history of the selected primates?

Does the nontaster allele exist in any nonhuman primate populations?

Which of the following statements best expresses the concept of punctuated equilibrium?

Evolutionary changes consist of rapid bursts of speciation alternating with long periods in which species remain essentially unmodified.

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

Finch beak depth was measured before and after a severe drought in 1977. The averaged results are shown in Figure 1. After the drought, there were fewer seeds available for the finches to eat and the seeds that did remain were larger and harder to crack open. Researchers claim that when large, hard seeds are the predominate food source, the average beak depth of these finches tends to increase in subsequent generations. Using the evidence provided, which of the following best justifies the researchers' claim?

Finch beak depth increased as a consequence of selective pressure after the drought because the remaining seeds were larger and harder.

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.

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.

Toxic substances often have a bitter taste that causes animals who try to eat such substances to spit them out rather than swallow them. Additional data suggest that gorilla populations have a very low frequency of nontasters. Which of the following best describes the likely evolution of the TAS2R38 locus in the gorilla population?

Gorillas who could taste bitter toxins were more likely to survive and reproduce than nontasters.

If the two finch populations are each in Hardy-Weinberg equilibrium and are isolated from each other, then which of the following graphs correctly displays the relative genotype frequencies?

Graph where island 1 and 2 are equal

Based on the data in Table 1, which of the following best explains the observed differences in cold tolerance between brown anoles (A. sagrei) and green anoles (A. carolinensis) in the United States?

Green anoles with greater tolerance for cold had greater reproductive success in areas with colder temperatures.

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.

Which of the following best describes the process responsible for the change in the percent of tuskless female elephants in the Gorongosa National Park population shown in Figure 1 ?

Human hunting of elephants with tusks between 1977 and 1992.

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.

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?

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.

Individuals of a particular species of ground beetle are either light tan or dark brown. Light-tan beetles are predominant in habitats with light-colored sandy soils, and dark-brown beetles are predominant in habitats with dark-colored loam soils. In an experiment designed to determine the survival rates of light-tan beetles and dark-brown beetles in different habitats, 500 light-tan beetles and 500 dark-brown beetles were released in each of four habitats. Each beetle had been marked with a small spot of red paint on the underside of its abdomen before it was released. One week after the beetles had been released, any marked beetles that could be found were recaptured. The results are presented in the table below. It is assumed that differences in the numbers of beetles recaptured are directly related to differences in survival rates. Which of the following can be inferred from the data in the table?

Insectivorous birds are predators of this species of ground beetle.

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.

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.

The phylogenetic trees in Figures 2 and 3 depict two different phylogenies of the same populations of sticklebacks. Which of the following questions will best help determine which tree represents the most accurate phylogeny?

Is the EDA gene as representative of the differences between the populations as the 25 random genes that were examined for Figure 3?

Which of the following statements best summarizes organic evolution as it is viewed by modern evolutionists?

It is the differential survival and reproduction of certain phenotypes.

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.

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.

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.

The bacteria have high genetic variability and high reproductive rates.

Males grown on starch paired with females grown on starch

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 (N2N2) gas and ammonia (NH3NH3) gas in experiment 1 could provide the elemental nitrogen required for the formation of amino acids.

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

Which of the following principles is NOT part of Darwin's theory of evolution by natural selection?

Mutations are the ultimate source of genetic variation.

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.

Which of the following best explains how Old World vultures and New World vultures both evolved to feed mainly on carrion?

Old World vultures and New World vultures were exposed to similar selective pressures, which contributed to the independent evolution of carrion feeding in two separate lineages.

Group IV of the cladogram most likely includes which of the following species?

P and S only

In a species of cactus, the number of spines on a plant is genetically determined. The graph above shows frequency distributions for populations of the cactus species growing in the presence or absence of two herbivores: peccaries (a New World pig) and wasp larvae. Which of the following best accounts for the different frequency distributions in the graph?

Peccaries eat cacti with a smaller number of spines, and wasp larvae eat cacti with a greater number of spines.

Which of the following experiments would specifically determine which gene is responsible for ceftazidime-avibactam sensitivity in P. aeruginosa ?

Perform gene knockout (targeted mutation) of either the hmgA, galU, or mexXY gene on separate cultures of the wild-type P. aeruginosa. For each individual mutant, determine whether or not ceftazidime-avibactam resistance has occurred.

To evaluate the reliability of the results, it would be best to know which of the following?

The number of males in each sample

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.

Which of the following best describes what happened to the otter population between 1750 and 1850 ?

The population lost genetic diversity as a result of a bottleneck effect.

Which of the following processes best explains why fewer light-tan beetles than dark-brown beetles were recaptured in habitat 4?

Predation

Which of the following best explains the changes in the phenotype frequencies of the stickleback population in Loberg Lake?

Predation in the marine environment is different from predation in Loberg Lake.

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?

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

Which of the following describes a possible selective mechanism to explain why freshwater sticklebacks typically have reduced pelvic spines?

Reduced pelvic spines increase the likelihood of escaping predators in freshwater environments.

Which of the following is the most likely reason for the observed differences in the frequency of the G allele between 1965 and 1972?

Selection against gray phenotypes

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.

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.

Based on the information provided, which of the following best describes the source of the rapid increase in milk production from 1976 to 2015 ?

Starting in the 1970s, farmers increased the selective breeding of cows and bulls for offspring that produced more milk.

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.

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 fitness.

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

Based on the experimental results, which of the following is the best evolutionary explanation for the occurrence of ARD in C. elegans ?

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

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.

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.

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.

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.

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.

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.

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.

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

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 group of mice was released into a large field to which no other mice had access. Immediately after the release, a representative sample of the mice was captured, and the fur color of each individual in the sample was observed and recorded. The mice were then returned to the field. After twenty years, another representative sample of the mice was captured, and the fur color of each individual in the sample was again recorded. Which of the following best explains the change in the frequency distribution of fur color phenotypes in the mouse population, as shown in the figures above?

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

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.

Based on the information in Table 1, which of the following statements best describes the production of nearly identical AFGPs in these two species of fish?

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

In a region of Africa where malaria is common, 9%9% of the population is born with a severe form of sickle-cell anemia (ssss). Carriers of the sickle-cell allele (heterozygotes) are resistant to malaria and display only mild symptoms of malaria if exposed to the malaria parasite. If an effective antimalarial program is instituted in the region, which of the following is most likely to occur over many generations?

The frequency of the sickle-cell allele ss will decrease as the incidence of malaria decreases.

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.

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.

Which of the following best represents the null hypothesis for the experiment detailed in Figure 1 ?

The mating preferences of flies are not dependent on the nutrient source on which they are grown.

Which of the following is an appropriate null hypothesis regarding the phenotypic frequencies of this population of salamanders before and after the flood?

The proportions of black, dark-brown, and light-brown salamanders before and after the flood are not significantly different, and any observed differences are due to random chance.

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 DNA.

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.

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.

The apple maggot fly, Rhagoletis pomonella, is native to North America and originally fed on fruit of the wild hawthorn. Since the mid-1800s, a population of flies has emerged that instead feed on domesticated apples. Apple maggot flies typically mate on or near the fruit of their host plants. Many varieties of apples ripen three to four weeks before the hawthorn fruits do. The different fruit preferences of the two fly populations will most likely have which of the following effects?

The single fly species will evolve into two distinct species because of the lack of gene flow between the two populations.

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.

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.

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 APOE gene, called APOE-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-ε2 allele. Which of the following states a valid null hypothesis about the future distribution of APOE 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.

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.F

Portions of the amino acid sequences of some dehydrogenase enzymes found in bacteria, yeast, corn, horses, and sheep are shown in Figure 1. Each letter represents a different amino acid in the sequence. Based on Figure 1, which of the following conclusions about the enzymes is most likely correct?

These enzymes all evolved from a common prokaryotic dehydrogenase enzyme, so they exhibit regions of sequence similarity.

Evolutionary fitness is measured by

reproductive success

Figure 1 illustrates a process that occurs in a certain group of organisms. Which of the following best predicts the importance of this process?

This process is common to all members of Eukarya and allows noncoding regions of RNA to be removed so that proteins with the correct amino acid sequence are produced.

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.

Researchers are investigating the evolutionary relationships among organisms found near deep-sea hydrothermal vents and similar organisms found closer to the ocean surface. Which of the following scientific questions is most relevant to the investigation?

What are the nucleotide sequences of ribosomal RNA genes that are found in the genomes of the different species?

Climate change is disrupting the length of winter in various ecosystems, resulting in less snowfall and milder winters. Scientists in Finland have been observing the tawny owl, a fairly large owl species that is commonly found in woodlands across much of Europe and Asia. Typically, the feathers of the upper body are either brown (BB) or gray (bb). Scientists studying tawny owls in Finland have found that the percentage of tawny owls that have brown feathers has increased over the past 28 years.

With milder winters, the advantage of gray feathers that blend into a snowy environment has decreased.

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?

X on the top on the second bracket

Which of the following cladograms provides the simplest and most accurate representation of the data in the table?

Y W V Z X

Which of the following is an independent variable in the investigation?

Year in which the sample was collected

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

an O2-rich atmosphere

The phenotypic variation in behavior between the two populations can best be described as resulting from

artificial selection

Competition for food would probably be most severe between two

closely related species in similar niches

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

A number of different phylogenies (evolutionary trees) have been proposed by scientists. These phylogenies are useful because they can be used to

evaluate which groups of organisms may be most closely related

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 above shows derived characters for selected organisms. Based on the information in the table, which of the following cladograms best represents the evolutionary relationships among the organisms?

fish amphibians crocodilians birds mammals

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

The different species of finches on the Galapagos Islands are believed to have arisen as a result of natural selection acting on populations of finches that had experienced

geographic isolation

The graph above shows the distribution of beak depth in a finch population that had been living on an island under conditions of normal rainfall. During a subsequent drought, the small seeds normally eaten by the finches were less available. Most of the available seeds were large seeds that could be eaten most easily by finches with deep beaks. Which of the following graphs best predicts the distribution of beak depth in the finch population after several years of drought?

graph that is increasing exponentially

The wing of a bat, the flipper of a whale, and the forelimb of a horse appear very different, yet detailed studies reveal the presence of the same basic bone pattern. These structures are examples of

homologous structures

Which of the following data sets is most likely to provide reliable information about the evolutionary relationships among these three snail species?

location of fossils and shell orientation

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?

low, same, different

Which of the following graphs best represents the type of selection most likely operating in the stickleback population of Loberg Lake?

one arrow pointing down on the far right

Which organism would the researchers most likely predict to be the most distantly related to eukaryotes?

organism 1

The best explanation for the fact that not all points lie on any given line is that

organisms within populations show variability

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

A group of people whose ancestors immigrated to North America 200 years ago have certain allele frequencies that differ significantly from those in surrounding populations in the United States. Which of the following is the most likely explanation for the difference in allele frequencies?

reproductive isolation

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

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 recessive for 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?

square root of 0.25

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

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