AP BIO Test 7

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?

0.29

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). 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

Gaucher disease type 1 (GD1) is a recessive genetic disease that affects 1 in 900 individuals in a particular population. GD1 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

One of the oldest known mammalian fossils belongs to a small furry species, Hadrocodium wui, that lived 195 million years ago.

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

Students analyzed several photosynthetic eukaryotic organisms in the laboratory to determine their phylogenetic relationships.

Cell wall composed of cellulose

Transposable elements are significant features in the genomes of almost all eukaryotic organisms. The accumulation of these elements in various species can help determine their relatedness. Table 1 indicates the presence (+) or absence (−) of 5 segments of DNA that have been moved by transposition (transposons) in 6 primate species. 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.

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.

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.

Staphylococcus aureus is a pathogenic bacterium that can infect a wide range of host species, including humans.

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 I and II) 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. Which of the following data could best support the claim that species B arose from a speciation event in Lake I?

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

Staphylococcus aureus is a pathogenic bacterium that can infect a wide range of host species, including humans.

Each strain is best adapted to a specific host species.

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.

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

African elephants, Loxodonta africana, are often hunted illegally for their tusks.

Human hunting of elephants with tusks between 1977 and 1992.

Figure 1 compares two models of speciation, A and B. 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.

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.

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

Location of fossils and shell orientation

The bird, Parus major, is commonly found in man-made habitats.

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

Researchers observed selected internal structures of four different microscopic organisms as part of a larger study on the divergence between eukaryotes and prokaryotes.

Organism I

Scientists investigated the role that beak depth plays in the ability of one species of seed-eating finch to reproduce.

Parental pairs with a specific beak depth had the highest reproductive fitness.

Researchers examined the ability of cultures of the bacterium Pseudomonas aeruginosa to adapt to the antibiotics ceftazidime and avibactam when they are administered together.

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

A scientist is attempting to provide support for the hypothesis that RNA was the first genetic material

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

Table 1 shows a trend of increasing milk yield for cows. Part of the increase in milk production can be attributed to improved nutrition and health protocols for dairy cows. 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.

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.

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 I and II) 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. Which of the following mechanisms could most likely account for the origin of species B in Lake I?

Sympatric speciation

A current challenge for doctors involves the bacterial strain Clostridioides difficile, which no longer responds to traditional antibiotic treatments.

The bacteria have high genetic variability and high reproductive rates.

Commercial bananas are grown as a monoculture, with all banana plants cloned from one original banana plant.

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.

Some scientists claim that amphibians are currently experiencing a period of mass extinction.

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−tetradecenyl acetate (11−TDA), which attracts males of their species.

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.

Two species of fish that live in extremely cold environments produce near-identical antifreeze glycoproteins, called AFGPs.

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

In eastern gray squirrels, Sciurus carolinensis, the allele for black fur (B) is dominant to the allele for gray fur (b).

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

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.

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

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. 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.

Students observed the distribution of different color phenotypes in northern ravine salamanders (Plethodon electromorphus) before and after a spring flood. The data are shown in Table 1. 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.

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.

In humans, one allele of the APOE gene, called APOE-ε2, can result in a high tolerance of cholesterol.

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.

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). 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.

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 DNA.

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 RNARNA to be removed so that proteins with the correct amino acid sequence are produced.

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. Which of the following best explains why the brown-feathered phenotype in tawny owls 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 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.

Over many years of a breeding program, a zoo has an established population of foxes that is well adapted for living in captivity. A representative sample of wild foxes from the neighboring forest was used to start the zoo population. A study was conducted to compare the behavior of the zoo fox population with the wild fox population in the neighboring forest. The behaviors of equal numbers of foxes from each population were assessed. Each fox's behavior was scored on a continuum from docile to aggressive based on its interaction with a trained behaviorist. The data is shown in Figure 1. The phenotypic variation in behavior between the two populations can best be described as resulting from

artificial selection