Question 1

Which statement about the relationship between genotype and phenotype is true?

Accepted Answer

A)  A given genotype always produces a specific phenotype. 
B)  Genotype alone determines phenotype. 
C)  A particular phenotype can be produced by more than one genotype. 
D)  The phenotypic expression of dominance makes the study of the genetic basis of natural selection easy. 
E)  The genotype is the physical expression of an organism's genes. 
A)  A given genotype always produces a specific phenotype. 
B)  Genotype alone determines phenotype. 
C)  A particular phenotype can be produced by more than one genotype. 
D)  The phenotypic expression of dominance makes the study of the genetic basis of natural selection easy. 
E)  The genotype is the physical expression of an organism's genes.

Question 2

Had Wallace died before sending a letter to Darwin, which circumstance would be most likely?

Accepted Answer

A)  Darwin's evolutionary theory would not have incorporated natural selection. 
B)  Darwin's evolutionary theory would not have considered descent with modification. 
C)  Darwin would have published his evolutionary theory later than he did. 
D)  Darwin would not have stressed gradual change in his theory. 
E)  Darwin would not have known about animal and plant breeding. 
A)  Darwin's evolutionary theory would not have incorporated natural selection. 
B)  Darwin's evolutionary theory would not have considered descent with modification. 
C)  Darwin would have published his evolutionary theory later than he did. 
D)  Darwin would not have stressed gradual change in his theory. 
E)  Darwin would not have known about animal and plant breeding.

Question 3

Selection currently maintains an intermediate body size in a population of salmon.Bears selectively prey on the largest individuals, while smaller individuals produce fewer offspring.Most likely, the population is experiencing _______ selection.

Accepted Answer

The answer of Selection currently maintains an intermediate body size...

Question 4

You discover a population of guppies and find it to be at Hardy-Weinberg equilibrium with respect to the S locus.Suppose there are two alleles at this locus and that the frequency of the s allele is 0.4.Of the individuals that carry at least one s allele, what fraction are homozygotes?

Accepted Answer

A)  1/8 
B)  1/6 
C)  1/4 
D)  1/3 
E)  1/2 
A)  1/8 
B)  1/6 
C)  1/4 
D)  1/3 
E)  1/2

Question 5

Asexual sawflies that migrate to North America become smaller over time.This change is shown to be genetic.The evolutionary mechanism that most likely explains this pattern is _______ selection.

Accepted Answer

The answer of Asexual sawflies that migrate to North America...

Question 6

Two populations of mice exist on either side of a river.After a bridge is constructed across the river, the two populations come to resemble each other more.What is the most likely explanation for this?

Accepted Answer

A)  Stabilizing selection 
B)  Directional selection 
C)  Gene flow 
D)  Genetic drift 
E)  Nonrandom mating 
A)  Stabilizing selection 
B)  Directional selection 
C)  Gene flow 
D)  Genetic drift 
E)  Nonrandom mating

Question 7

There are three isolated populations of garter snakes: population A has had a constant population size of about 50,000, population B has had a constant population size of about 12,000, and population C has had a constant population size of about 2,000.We would expect to see the greatest fluctuations of allele frequencies in population _______ because this population would experience the _______ genetic drift.

Accepted Answer

A)  A; most 
B)  A; least 
C)  B; most 
D)  C; most 
E)  C; least 
A)  A; most 
B)  A; least 
C)  B; most 
D)  C; most 
E)  C; least

Question 8

A sparrow population currently eats seeds that are mostly of medium size.Which condition will most likely lead to more directional selection?

Accepted Answer

A)  A decrease in population size of the sparrow 
B)  More seeds that are either considerably smaller or considerably larger than average, with fewer of intermediate size 
C)  More seeds that are intermediate in size 
D)  More seeds that are somewhat larger than average and fewer that are smaller than average 
E)  A reduction in the overall number of seeds, with no change in the distribution 
A)  A decrease in population size of the sparrow 
B)  More seeds that are either considerably smaller or considerably larger than average, with fewer of intermediate size 
C)  More seeds that are intermediate in size 
D)  More seeds that are somewhat larger than average and fewer that are smaller than average 
E)  A reduction in the overall number of seeds, with no change in the distribution

Question 9

An allele in a population of trout has a frequency of 0.37.In 300 trout, how many copies of the allele are present?

Accepted Answer

A)  148 
B)  222 
C)  268 
D)  302 
E)  324 
A)  148 
B)  222 
C)  268 
D)  302 
E)  324

Question 10

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results.   In strain, mutations are accumulating at a(n)

Accepted Answer

A)  linear rate of about 3 per generation. 
B)  linear rate of about 6 per generation. 
C)  linear rate of about 30 per generation. 
D)  accelerating (faster than linear) rate. 
E)  decelerating (slower than linear) rate. 
A)  linear rate of about 3 per generation. 
B)  linear rate of about 6 per generation. 
C)  linear rate of about 30 per generation. 
D)  accelerating (faster than linear) rate. 
E)  decelerating (slower than linear) rate.

Question 11

A population of salmon is becoming increasingly small over succeeding generations.This trend does not appear to be due to environmental changes, but rather to selection due to the fishing industry.What type of selection is occurring?

Accepted Answer

Directiona

Question 12

Refer to the graph showing beak size for a population of a species of Darwin's finches.   Draw a graph showing what the resulting population would most likely look like after a generation of stronger stabilizing selection.

Accepted Answer

The answer of Refer to the graph showing beak size...

Question 13

Pharyngeal nerves in vertebrates are much longer than the direct distance from the central nervous system to the target, because they evolved from preexisting structures.As a result, these nerves are not as efficient as they otherwise could be.Which term best explains this phenomenon?

Accepted Answer

A)  Trade-offs 
B)  Heterozygote deficiency 
C)  Muller's ratchet 
D)  Adaptation 
E)  Developmental constraint 
A)  Trade-offs 
B)  Heterozygote deficiency 
C)  Muller's ratchet 
D)  Adaptation 
E)  Developmental constraint

Question 14

Suppose the population size of a species of field mice is 2 million.It has a mutation rate of 2 × 10-9, and its genome size is 3 billion bp.The number of new mutations that appear in this species would be about _______.

Accepted Answer

Question 15

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results.   The population is accumulating mutations at a rate of about _______ mutations per generation.

Accepted Answer

The answer of Yeast cells are sequenced periodically to examine...

Question 16

In a population at Hardy-Weinberg equilibrium with only two alleles at locus A, the frequency of A alleles is 0.1.The frequency of heterozygotes for this allele is

Accepted Answer

A)  0.01. 
B)  0.02. 
C)  0.09. 
D)  0.18. 
E)  0.50. 
A)  0.01. 
B)  0.02. 
C)  0.09. 
D)  0.18. 
E)  0.50.

Question 17

A locus has two alleles.The frequency of heterozygotes in a population at Hardy-Weinberg equilibrium is 0.32.What is the frequency of the more common of the two alleles?

Accepted Answer

A)  0.9 
B)  0.8 
C)  0.64 
D)  0.32 
E)  0.16 
A)  0.9 
B)  0.8 
C)  0.64 
D)  0.32 
E)  0.16

Question 18

Which type of selection is most likely to result in an evolutionary trend?

Accepted Answer

A)  Stabilizing 
B)  Directional 
C)  Disruptive 
D)  Purifying 
E)  None of the above; selection cannot result in evolutionary trends. 
A)  Stabilizing 
B)  Directional 
C)  Disruptive 
D)  Purifying 
E)  None of the above; selection cannot result in evolutionary trends.

Question 19

A population of salmon is becoming increasingly small over the generations.This trend does not appear to be due to environmental changes, but rather to selection due to the fishing industry.Draw the relationship between body size and fitness that is occurring in this population.

Accepted Answer

The answer of A population of salmon is becoming increasingly...

Question 20

A population of 600 horses has 70 individuals that are AA and 160 that are Aa at a locus involved in immune response.Assuming that these are the only alleles at that locus, what is the frequency of a?

Accepted Answer

A)  0.25 
B)  0.3 
C)  0.5 
D)  0.75 
E)  There is not enough information to answer this question. 
A)  0.25 
B)  0.3 
C)  0.5 
D)  0.75 
E)  There is not enough information to answer this question.

Exam 20: Mechanisms of Evolution

Which statement about the relationship between genotype and phenotype is true?

Had Wallace died before sending a letter to Darwin, which circumstance would be most likely?

Selection currently maintains an intermediate body size in a population of salmon.Bears selectively prey on the largest individuals, while smaller individuals produce fewer offspring.Most likely, the population is experiencing _______ selection.

You discover a population of guppies and find it to be at Hardy-Weinberg equilibrium with respect to the S locus.Suppose there are two alleles at this locus and that the frequency of the s allele is 0.4.Of the individuals that carry at least one s allele, what fraction are homozygotes?

Asexual sawflies that migrate to North America become smaller over time.This change is shown to be genetic.The evolutionary mechanism that most likely explains this pattern is _______ selection.

Two populations of mice exist on either side of a river.After a bridge is constructed across the river, the two populations come to resemble each other more.What is the most likely explanation for this?

A sparrow population currently eats seeds that are mostly of medium size.Which condition will most likely lead to more directional selection?

An allele in a population of trout has a frequency of 0.37.In 300 trout, how many copies of the allele are present?

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. In strain, mutations are accumulating at a(n)

A population of salmon is becoming increasingly small over succeeding generations.This trend does not appear to be due to environmental changes, but rather to selection due to the fishing industry.What type of selection is occurring?

Refer to the graph showing beak size for a population of a species of Darwin's finches. Draw a graph showing what the resulting population would most likely look like after a generation of stronger stabilizing selection.

Pharyngeal nerves in vertebrates are much longer than the direct distance from the central nervous system to the target, because they evolved from preexisting structures.As a result, these nerves are not as efficient as they otherwise could be.Which term best explains this phenomenon?

Suppose the population size of a species of field mice is 2 million.It has a mutation rate of 2 × 10-9, and its genome size is 3 billion bp.The number of new mutations that appear in this species would be about _______.

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. The population is accumulating mutations at a rate of about _______ mutations per generation.

In a population at Hardy-Weinberg equilibrium with only two alleles at locus A, the frequency of A alleles is 0.1.The frequency of heterozygotes for this allele is

A locus has two alleles.The frequency of heterozygotes in a population at Hardy-Weinberg equilibrium is 0.32.What is the frequency of the more common of the two alleles?

Which type of selection is most likely to result in an evolutionary trend?

A population of salmon is becoming increasingly small over the generations.This trend does not appear to be due to environmental changes, but rather to selection due to the fishing industry.Draw the relationship between body size and fitness that is occurring in this population.

A population of 600 horses has 70 individuals that are AA and 160 that are Aa at a locus involved in immune response.Assuming that these are the only alleles at that locus, what is the frequency of a?

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Suppose the population size of a species of field mice is 2 million.It has a mutation rate of 2 × 10^-9, and its genome size is 3 billion bp.The number of new mutations that appear in this species would be about _______.