No student devices needed. Know more
18 questions
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.
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.
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.
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.
A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following procedures was most likely followed to determine the change in beak size?
A few finches were trapped in 1981 and again in 1987, and their beak sizes were compared.
The beak size in fifteen finches was measured in 1987, and the beak size in the original finches was determined by estimation.
The beak size in a large number of finches was measured every year from 1981 to 1987.
Finches were captured and bred in 1981, and the beak size of the offspring was measured.
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?
The formation of two new finch species from a single parent species
A change in gene frequencies in the finch population due to selective pressure from the environmental change
A new allele appearing in the finch population as a result of mutation
The achievement of dynamic equilibrium in the finch population as a result of homeostasis
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?
The greatest increase in antibiotic resistance occurred from the first year to the third year of the study.
Gene flow in the population occurred at the same rate for the entire duration of the eight-year study.
Because evolution in bacterial populations occurs over millions of years, the results are due to random variation.
Natural selection over multiple generations is favoring antibiotic resistance in the population of bacteria.
A current challenge for doctors involves the bacterial strain Clostridioides difficile, which no longer responds to traditional antibiotic treatments.
Which of the following best explains why this particular strain of bacteria is resistant to antibiotic treatment?
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.
The bird, Parus major, is commonly found in man-made habitats. During the summer these birds primarily feed on insects, and in the winter, when insects are scarce, they forage in gardens and bird feeders for seeds, nuts, and berries. Recently, climate change has led to a decrease in food available from gardens, and scientists have observed that the average beak length of the birds has increased.
Which of the following best explains the directional shift in beak length in these birds?
Longer beaks allow the birds to better fend off predators.
Longer beaks increase the fitness of the birds in wild habitats.
Longer beaks allow the birds to better access seeds in bird feeders.
Longer beaks decrease the fitness of the birds in wild habitats.
Modern bananas originated from a cross between a tetraploid banana species and a diploid banana species. The product of this cross was the triploid Cavendish banana strain, a sterile hybrid that is only grown asexually. Recently, the Panama fungus has been observed more frequently parasitizing the Cavendish banana, and scientists claim that this type of banana is on the brink of extinction.
Which of the following provides the best explanation of the scientists’ claim regarding the threat to the Cavendish banana?
The triploid genome of the Cavendish banana makes it susceptible to the negative impact of recessive alleles.
Having three of each chromosome interferes with normal function of the cells and increases the likelihood of contracting a disease.
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.
Asexual reproduction increases the mutation rate during replication, resulting in a greater chance that the offspring have a dysfunctional immune system.
The Tasmanian devil (Sarcophilus harrisii) is a species of mammal whose only wild population is native to the isolated island of Tasmania, off the coast of Australia. Tasmanian devils have a very low level of genetic diversity across the entire species. Researchers hypothesize this lack of diversity is the result of several genetic bottlenecks in the species’ history.
In 1996 a new disease called devil facial tumor disease (DFTD
) appeared in the wild Tasmanian devil population. DFTD
can spread from one animal to another and causes the death of most affected animals. The impact of DFTD
on the Tasmanian devil population has resulted in a decrease in the total population of more than 85% over the last two decades. (a) Describe the process that maintained a stable Tasmanian devil population size before the appearance of DFTD
in 1996.
The Tasmanian devil (Sarcophilus harrisii) is a species of mammal whose only wild population is native to the isolated island of Tasmania, off the coast of Australia. Tasmanian devils have a very low level of genetic diversity across the entire species. Researchers hypothesize this lack of diversity is the result of several genetic bottlenecks in the species’ history.
In 1996 a new disease called devil facial tumor disease (DFTD
) appeared in the wild Tasmanian devil population. DFTD
can spread from one animal to another and causes the death of most affected animals. The impact of DFTD
on the Tasmanian devil population has resulted in a decrease in the total population of more than 85% over the last two decades. (b) Explain how the huge reduction of the Tasmanian devil population since 1996 affects the susceptibility of the current population to new diseases in comparison with the susceptibility of the population before 1996.
The Tasmanian devil (Sarcophilus harrisii) is a species of mammal whose only wild population is native to the isolated island of Tasmania, off the coast of Australia. Tasmanian devils have a very low level of genetic diversity across the entire species. Researchers hypothesize this lack of diversity is the result of several genetic bottlenecks in the species’ history.
In 1996 a new disease called devil facial tumor disease (DFTD
) appeared in the wild Tasmanian devil population. DFTD
can spread from one animal to another and causes the death of most affected animals. The impact of DFTD
on the Tasmanian devil population has resulted in a decrease in the total population of more than 85% over the last two decades. (c) Tasmanian devils are top predators and are considered a keystone species in their community. Predict the effect of the rapid reduction of the Tasmanian devil population on the rest of the community. Justify your answer.
Researchers analyzed the amino sequence of the protein cytochrome c
in various groups of organisms and determined the number of amino substitutions that have occurred in the different groups of organisms. They plotted the data with respect to the time since divergence of the members of paired groups from a common ancestor (Figure 1). Based on the data, which of the following organisms are most distantly related?
Birds and mammals
Mammals and reptiles
Fish and land vertebrates
Insects and vertebrates
Goats and sheep belong to the same family but different genera. While they often live together in the same pastures, the hybrid offspring that are occasionally produced between the two species rarely survive. When such a hybrid does survive, it is usually sterile.
Which of the following best explains the mechanism that maintains reproductive isolation between goats and sheep?
Gene flow is prevented because the two species belong to different trophic levels and therefore do not share a food source.
Habitat isolation creates a prezygotic barrier between the two species.
The males of one species and the females of the other species are fertile at different times.
The two species have a different number of chromosomes, resulting in a postzygotic barrier.
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?
The gene for methicillin resistance, no longer needed, would disappear entirely from Staphylococcus aureus populations within a few generations.
Transmission of the methicillin-resistance plasmid by conjugation would increase among the Staphylococcus aureus population as the genes would confer resistance to the new antibiotic.
Transmission of the methicillin-resistance plasmid would gradually decrease but the plasmid would not entirely disappear from the Staphylococcus aureus population.
Transmission of the methicillin-resistance plasmid by conjugation would increase among the Staphylococcus aureus population due to destruction of bacteria without the plasmid through use of the new antibiotic.
Many species of corals are threatened by the increasing temperatures and decreasing pH
of ocean waters. One species, Stylophora pistillata, has been found to thrive in water that is warmer and has a lower pH
than the water that corals typically thrive in. Additionally, researchers have found that the tolerance for the new water conditions is heritable.
Which of the following statements best explains the changes seen in S. pistillata in response to the changing water conditions?
The corals’ adaptation is an example of natural selection because the tolerance is in response to a changing environment and has a genetic basis.
The corals’ adaptation is an example of the founder effect because the majority of corals do not have a tolerance for warmer water.
The corals’ adaptation is an example of genetic drift because the change was a chance event and not the result of selection in response to environmental change.
The corals’ adaptation is an example of adaptive radiation because it has resulted in a wide range of species adapting to the new ocean conditions.
The figure shows a phylogenetic tree of various members of the order Proboscidea, which includes modern elephants. Which of the following claims is best supported by the information in the figure ?
The Asian and African elephants are the most closely related species shown on the tree.
The mammoth diverged from its most recent common ancestor with African elephants before the mastodon diverged from its most recent common ancestor with Stegodons.
The mastodon and the Stegodon diverged from their common ancestor 2 million years ago.
The common ancestor of the African elephant and the mastodon is the Palaeomastodon.
Explore all questions with a free account