Question 1

In addition to Darwin, who do we credit for formulating the theory of evolution by natural selection?

Accepted Answer

A)  Gregor Mendel 
B)  Jean-Baptiste Lamarck 
C)  James Watson 
D)  Alfred Russel Wallace 
E)  Thomas Hunt Morgan 
A)  Gregor Mendel 
B)  Jean-Baptiste Lamarck 
C)  James Watson 
D)  Alfred Russel Wallace 
E)  Thomas Hunt Morgan

Question 2

Following is a list of the performance of the different genotypes at the S locus in two environments for three populations of lizards.The first number is their running speed (in m/s), and the second is their relative strength.   In which population(s) is there evidence for a trade-off between running speed and relative strength?

Accepted Answer

A)  Only population 1 
B)  Only population 2 
C)  Only population 3 
D)  Both populations 1 and 2 
E)  None of the populations 
A)  Only population 1 
B)  Only population 2 
C)  Only population 3 
D)  Both populations 1 and 2 
E)  None of the populations

Question 3

Next-generation sequencing reveals that six new mutations have occurred in the coding regions of genes in an individual diploid fly.If the coding regions of this fly comprise 100 million nucleotides per haploid genome, what is the mutation rate per nucleotide?

Accepted Answer

A)  3 per billion 
B)  15 per billion 
C)  30 per billion 
D)  60 per billion 
E)  15 per million 
A)  3 per billion 
B)  15 per billion 
C)  30 per billion 
D)  60 per billion 
E)  15 per million

Question 4

Calculate the frequency of homozygotes for an allele at a locus in a population at Hardy-Weinberg equilibrium if the frequency of the allele is 0.15.

Accepted Answer

A)  0.0225 
B)  0.045 
C)  0.15 
D)  0.255 
E)  0.3 
A)  0.0225 
B)  0.045 
C)  0.15 
D)  0.255 
E)  0.3

Question 5

A large meteor hit Earth 66 million years ago.As a result, most large animals went extinct, including the nonavian dinosaurs, despite their success for millions of years before that time.This is an example of

Accepted Answer

A)  trade-offs. 
B)  Crichton's law. 
C)  Muller's ratchet. 
D)  developmental constraints. 
E)  differing long- and short-term patterns of evolutionary change. 
A)  trade-offs. 
B)  Crichton's law. 
C)  Muller's ratchet. 
D)  developmental constraints. 
E)  differing long- and short-term patterns of evolutionary change.

Question 6

Sexual reproduction would be least likely to evolve when

Accepted Answer

A)  parasites are frequent. 
B)  DNA repair is exceptionally good. 
C)  particular combinations of alleles not currently present in the population are favored. 
D)  population sizes are small. 
E)  environmental conditions are variable from generation to generation. 
A)  parasites are frequent. 
B)  DNA repair is exceptionally good. 
C)  particular combinations of alleles not currently present in the population are favored. 
D)  population sizes are small. 
E)  environmental conditions are variable from generation to generation.

Question 7

A species of yeast can reproduce either sexually or asexually.Five populations of this yeast were initially asexual but were moved to different environments.Which population would likely evolve sexual reproduction and recombination?

Accepted Answer

A)  Population A, which has a very large population size 
B)  Population B, which experiences steady temperatures 
C)  Population C, which has evolved a more efficient DNA repair system 
D)  Population D, which is in an environment without pathogens 
E)  Population E, which experiences a rapidly changing environment 
A)  Population A, which has a very large population size 
B)  Population B, which experiences steady temperatures 
C)  Population C, which has evolved a more efficient DNA repair system 
D)  Population D, which is in an environment without pathogens 
E)  Population E, which experiences a rapidly changing environment

Question 8

The table shows the number of offspring produced by individuals of three genotypes at the B locus in five different populations.   Assuming survival rates and all other factors are equal across genotypes, in which population would you most likely expect variation at the B locus to be maintained?

Accepted Answer

A)  Population 1 
B)  Population 2 
C)  Population 3 
D)  Population 4 
E)  Population 5 
A)  Population 1 
B)  Population 2 
C)  Population 3 
D)  Population 4 
E)  Population 5

Question 9

The sizes of eyes in a population of spiders are monitored over several generations.The average eye size does not noticeably change, but the range of variation decreases.Assuming that no other evolutionary processes are occurring, what type of selection is most likely taking place?

Accepted Answer

A)  Frequency-dependent 
B)  Stabilizing 
C)  Diversifying 
D)  Sexual 
E)  None of the above; selection is not operating. 
A)  Frequency-dependent 
B)  Stabilizing 
C)  Diversifying 
D)  Sexual 
E)  None of the above; selection is not operating.

Question 10

Malte Andersson's study of widowbirds demonstrated that

Accepted Answer

A)  females prefer males with unaltered tails. 
B)  the preferences of females change according to the season. 
C)  sexually selected traits have no benefits or costs to survivorship. 
D)  long tails help males compete physically with other males. 
E)  females prefer males with longer-than-average tails. 
A)  females prefer males with unaltered tails. 
B)  the preferences of females change according to the season. 
C)  sexually selected traits have no benefits or costs to survivorship. 
D)  long tails help males compete physically with other males. 
E)  females prefer males with longer-than-average tails.

Question 11

Which of the following statements about the Hardy-Weinberg equilibrium is false?

Accepted Answer

A)  It applies only to sexual populations. 
B)  It applies to populations in which there is no gene flow. 
C)  It assumes that populations are infinite. 
D)  It assumes that individuals prefer to mate with individuals with certain genotypes. 
E)  It applies to populations that are not experiencing natural selection. 
A)  It applies only to sexual populations. 
B)  It applies to populations in which there is no gene flow. 
C)  It assumes that populations are infinite. 
D)  It assumes that individuals prefer to mate with individuals with certain genotypes. 
E)  It applies to populations that are not experiencing natural selection.

Question 12

Biologists recently discovered that black wolves got their coat color from exchanging genes with dogs.This is an example of

Accepted Answer

A)  genetic drift. 
B)  gene pools. 
C)  gene flow. 
D)  a founder effect. 
E)  an adaptation. 
A)  genetic drift. 
B)  gene pools. 
C)  gene flow. 
D)  a founder effect. 
E)  an adaptation.

Question 13

By definition, a population that is fixed for an allele _______ at that locus.

Accepted Answer

A)  is polymorphic 
B)  is monomorphic 
C)  lacks genetic structure 
D)  is experiencing selection 
E)  is experiencing mutation 
A)  is polymorphic 
B)  is monomorphic 
C)  lacks genetic structure 
D)  is experiencing selection 
E)  is experiencing mutation

Question 14

Suppose a population of flour beetles has 1,000 individuals.Normally the beetles are red; however, this population is polymorphic for a mutant autosomal body color, black, designated by bb.Red is dominant to black, so BB and Bb genotypes are red.Assume the population is at Hardy-Weinberg equilibrium, with equal frequencies of the two alleles.What would be the expected frequencies of the homozygous dominant, heterozygous, and homozygous recessive genotypes (in that order) after 100 generations, assuming that no selection or other evolutionary processes were operating?

Accepted Answer

A)  0.25, 0.5, 0.25 
B)  0.75, 0.20, 0.05 
C)  0, 0.5, 0.5 
D)  0, 0, 1 
E)  1, 0, 0 
A)  0.25, 0.5, 0.25 
B)  0.75, 0.20, 0.05 
C)  0, 0.5, 0.5 
D)  0, 0, 1 
E)  1, 0, 0

Question 15

The generation of broccoli from the ancestral Brassica oletracea was achieved by _______ selection for specific features of the _______.

Accepted Answer

A)  artificial; leaves 
B)  artificial; stems and flowers 
C)  artificial; terminal buds 
D)  natural; leaves 
E)  natural; stems and flowers 
A)  artificial; leaves 
B)  artificial; stems and flowers 
C)  artificial; terminal buds 
D)  natural; leaves 
E)  natural; stems and flowers

Question 16

Which is not a condition for Hardy-Weinberg equilibrium?

Accepted Answer

A)  Absence of gene flow 
B)  Absence of differential survival among genotypes 
C)  Random mating of individuals with respect to genotype 
D)  Absence of genetic drift that would cause chance fluctuations of allele frequencies 
E)  Small population size 
A)  Absence of gene flow 
B)  Absence of differential survival among genotypes 
C)  Random mating of individuals with respect to genotype 
D)  Absence of genetic drift that would cause chance fluctuations of allele frequencies 
E)  Small population size

Question 17

The numbers of fledged young of female swamp sparrows of different sizes were assayed and are presented in the table.   Assume that body size is at least partially heritable.What is the most likely response to selection in population B?

Accepted Answer

A)  Body size would increase. 
B)  Body size would decrease. 
C)  Body size would stay more or less the same, but the variance would increase. 
D)  Body size would stay more or less the same, but the variance would decrease. 
E)  None of the above; there is no selection occuring. 
A)  Body size would increase. 
B)  Body size would decrease. 
C)  Body size would stay more or less the same, but the variance would increase. 
D)  Body size would stay more or less the same, but the variance would decrease. 
E)  None of the above; there is no selection occuring.

Question 18

Positive selection can produce _______.

Accepted Answer

The answer of Positive selection can produce _______....

Question 19

Suppose mutation and selection no longer occurred in a small, isolated population of nematodes.Which process would most likely continue operating, and what would be the most likely effect on the extent of genetic variation?

Accepted Answer

A)  Gene flow would lead to an increase in genetic variation. 
B)  Gene flow would lead to a decrease in genetic variation. 
C)  Genetic drift would lead to an increase in genetic variation. 
D)  Genetic drift would lead to a decrease in genetic variation. 
E)  Genetic drift would operate but would have no effect on genetic variation. 
A)  Gene flow would lead to an increase in genetic variation. 
B)  Gene flow would lead to a decrease in genetic variation. 
C)  Genetic drift would lead to an increase in genetic variation. 
D)  Genetic drift would lead to a decrease in genetic variation. 
E)  Genetic drift would operate but would have no effect on genetic variation.

Question 20

A population of crickets has 84 individuals that are homozygous for one allele, 152 that are heterozygous, and 184 that are homozygous for the other allele.Compared with Hardy-Weinberg expectations, this population has _______ too few heterozygotes.

Accepted Answer

The answer of A population of crickets has 84 individuals...

Exam 20: Mechanisms of Evolution

In addition to Darwin, who do we credit for formulating the theory of evolution by natural selection?

Next-generation sequencing reveals that six new mutations have occurred in the coding regions of genes in an individual diploid fly.If the coding regions of this fly comprise 100 million nucleotides per haploid genome, what is the mutation rate per nucleotide?

Calculate the frequency of homozygotes for an allele at a locus in a population at Hardy-Weinberg equilibrium if the frequency of the allele is 0.15.

A large meteor hit Earth 66 million years ago.As a result, most large animals went extinct, including the nonavian dinosaurs, despite their success for millions of years before that time.This is an example of

Sexual reproduction would be least likely to evolve when

A species of yeast can reproduce either sexually or asexually.Five populations of this yeast were initially asexual but were moved to different environments.Which population would likely evolve sexual reproduction and recombination?

The table shows the number of offspring produced by individuals of three genotypes at the B locus in five different populations. Assuming survival rates and all other factors are equal across genotypes, in which population would you most likely expect variation at the B locus to be maintained?

The sizes of eyes in a population of spiders are monitored over several generations.The average eye size does not noticeably change, but the range of variation decreases.Assuming that no other evolutionary processes are occurring, what type of selection is most likely taking place?

Malte Andersson's study of widowbirds demonstrated that

Which of the following statements about the Hardy-Weinberg equilibrium is false?

Biologists recently discovered that black wolves got their coat color from exchanging genes with dogs.This is an example of

By definition, a population that is fixed for an allele _______ at that locus.

The generation of broccoli from the ancestral Brassica oletracea was achieved by _______ selection for specific features of the _______.

Which is not a condition for Hardy-Weinberg equilibrium?

The numbers of fledged young of female swamp sparrows of different sizes were assayed and are presented in the table. Assume that body size is at least partially heritable.What is the most likely response to selection in population B?

Positive selection can produce _______.

Suppose mutation and selection no longer occurred in a small, isolated population of nematodes.Which process would most likely continue operating, and what would be the most likely effect on the extent of genetic variation?

A population of crickets has 84 individuals that are homozygous for one allele, 152 that are heterozygous, and 184 that are homozygous for the other allele.Compared with Hardy-Weinberg expectations, this population has _______ too few heterozygotes.

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