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- 1. Multiple Choice
In an experiment, 100 mice were released into a field to which no other mice had access. Immediately after their release, a representative sample of mice was captured, their fur color was recorded, and they were returned to the field. After twenty years, a representative sample of mice was captured and the distribution of fur color was again recorded. Which of the following could best explain the change in fur color distribution, as shown in the table above?
The allele for black fur color is unstable, and over twenty years most of the black fur alleles mutated to become alleles for gray fur.
The field was primarily composed of light-colored soil and little vegetation, affording gray mice protection from predators.
Sexual selection led to increased mating frequency of black and brown versus gray and brown.
The gray mice were harder to catch, and so were underrepresented in the twenty-year sample.
- 2. Multiple Choice
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?
The founder effect suggests that dark-colored snails migrated from the southern regions to the north and established the populations found there.
Genetic drift at the shell-color locus caused the northern population to become homozygous for the dark-color allele.
The mutation rate is higher in the south, as the longer days expose the snails to more ultraviolet radiation than in the north.
Dark-colored snails absorb more solar energy and so survive more readily in the colder northern waters.
- 3. Multiple Choice
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?
Are the genes encoding the proteolytic enzymes expressed in the same cell types in all species?
Once the precursor proteins of different species are cleaved, do the active signaling proteins bind to the same receptors on different target cells?
If a proteolytic enzyme from one species is incubated with a precursor protein from another species, does correct cleavage occur?
Are the proteolytic enzymes synthesized in the rough endoplasmic reticulum of all species?
- 4. Multiple Choice
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?
The data support convergent evolution for nitrogen excretion in organisms occupying dramatically different environmental niches.
The nitrogenous waste excreted by each vertebrate is the result of evolutionary adaptations that have decreased vulnerability to predators.
Nitrogen homeostasis in terrestrial vertebrates reflects an adaptation for more frequent and higher-volume urination than that occurring in aquatic vertebrates.
Ammonia secretion requires a large volume of water and was therefore selected against in terrestrial vertebrates.
- 5. Multiple Choice
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
The extinction rate of amphibians in the 21st century compared with the extinction rate of amphibians during the 20th century
The number of species of amphibians currently alive compared with the number of amphibian species known to be extinct
The number of new amphibian species being discovered per year compared with the number of amphibian species becoming extinct during the same time period
- 6. Multiple Choice
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?
Courtship rituals specific to each island lizard species prevent the lizards from interbreeding.
Speciation results from bottleneck events that happened before the ancestral species reached the islands.
The different species that currently exist are the result of hybridization between lizards from different islands.
The isolation prevents gene flow; thus, the lizards on different islands experience prezygotic isolation.
- 7. Multiple Choice
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?
Penguins live on land and feed in the water; therefore they have no need to fly.
The Antarctic home of penguins is flat and barren; therefore there is no place to fly.
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.
Ancestral penguins did not use their wings for long periods of time; therefore today’s penguins have only tiny, nonfunctional wings.
The cold and wind of Antarctica make flight impossible; therefore penguins that live there have lost the ability to fly.
- 8. Multiple Choice
A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of moths in the natural population was white in 1962 ?
2%
4%
8%
20%
64%
- 9. Multiple Choice
A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of the gray moths that emerged in 1980 was heterozygous?
0%
25%
33%
67%
100%
- 10. Multiple Choice
A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what was the frequency of allele G in the gray moths that emerged in 1980?
0.33
0.50
0.67
0.75
1.00
- 11. Multiple Choice
For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet.
A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law.
What is the frequency of the recessive allele?
√0.75
0.75
√0.50
√0.25
0.25
- 12. Multiple Choice
For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet.
A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law.
Unlike most natural populations, this population is best characterized in which of the following ways?
There is genetic equilibrium.
There is gene flow.
There is genetic drift.
Mutations occur.
Mating is nonrandom.
- 13. Multiple Choice
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?
p2
q2
2pq
p2 + 2pq
p2 + q2
- 14. Multiple Choice
Item 18A current challenge for doctors involves the bacterial strain Clostridioides difficile, which no longer responds to traditional antibiotic treatments.
Which of the following best explains why this particular strain of bacteria is resistant to antibiotic treatment?
Mutations creating new alleles occur more frequently in this species of bacteria than in other species.
The bacteria have high genetic variability and high reproductive rates.
Crossing over during meiosis increased genetic variability in the bacteria.
The bacteria are able to recognize and destroy the antibiotics by breaking them down extracellularly.
- 15. Multiple Choice
Commercial bananas are grown as a monoculture, with all banana plants cloned from one original banana plant. The commercial strains of bananas are seedless, so each new banana plant has to be manually planted from a cutting of an existing banana root. In the 1950s, the Gros Michel banana strain, the dominant export banana at that time, was destroyed by the fungus Fusarium oxysporum. A new Fusarium resistant variety, the Cavendish banana, was developed and is currently the banana strain grown for export. Recently, a Fusarium strain that successfully attacks the Cavendish strain has been documented.
Which of the following best provides reasoning supporting a method that would help protect commercial banana crops from infection by pathogenic organisms such as Fusarium fungi?
The commercial banana strains should be exposed to X-rays to encourage random mutations that will then be passed to offspring, producing resistance to pathogenic organisms.
The Cavendish banana plants should be exposed to pathogenic organisms under controlled conditions, so the plants can be encouraged to mutate and develop resistance to the pathogens.
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.
Growing the Cavendish strain under different conditions will allow natural selection to produce the variation needed to resist infection by pathogenic organisms.
- 16. Multiple Choice
The condition in which there are barriers to successful interbreeding between individuals of different species in the same community is referred to as
latent variations
sterility
structural differences
geographic isolation
reproductive isolation
- 17. Multiple Choice
Use the phylogenetic tree in Figure 1 to estimate the age in hundreds of thousands of years of the most recent common ancestor of all brown bears. Identify the population of brown bears to which polar bears are most closely related based on the mitochondrial DNA sequence comparison. Identify two populations whose positions could be switched without affecting the relationships illustrated in the cladogram.
30-35
European
European/Polar
Asian / Western North American
All of the above
- 18. Multiple Choice
A student claims that mitochondrial DNA sequence comparisons provide a more accurate phylogeny of bear species than do LYST protein sequence comparisons. Provide ONE piece of reasoning to support the student’s claim.
Genes show more variability (in nucleotide sequence) than proteins do (in amino acid sequences).
mtDNA genome contains multiple genes vs. one lyst gene.
The phenotype associated with the lyst gene is under strong selection.
All of the above
- 19. Multiple Choice
A researcher genetically engineers a mouse strain by deleting the mouse lyst gene and replacing it with the polar bear lyst gene. Predict the most likely difference in phenotype of the transgenic mouse strain compared to the wild-type mouse strain. Justify your prediction.
Mouse fur and/or eyes will not have pigment/will have reduced pigment.
Mouse (fur) will be white/lighter.
Polar bear lyst gene/LYST protein is associated with a lack of pigment/white hair.
Mutated human lyst gene/ LYST protein is associated with a lack of pigment in hair and eyes.
All of the above
- 20. Multiple Choice
Construct a cladogram on the template to represent a model of the evolutionary relatedness among the bear species based on the differences in LYST protein sequences (Table 1). Circle the position on the cladogram that represents the out-group.
Pandas would be the outgroup
All of the above
- 21. Multiple Choice
Describe how the mutation in the lyst gene became common in the polar bear population. If the lyst gene were the only determinant of fur color, predict the percent of white offspring produced by a mating between a polar bear and a brown bear
Natural selection for the white fur phenotype
0%
All of the above
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