Question 1

According to its scientific definition, a theory is

Accepted Answer

A)  a hypothesis. 
B)  largely a matter of guesswork. 
C)  based on a large body of knowledge. 
D)  an estimate. 
E)  a supposition. 
A)  a hypothesis. 
B)  largely a matter of guesswork. 
C)  based on a large body of knowledge. 
D)  an estimate. 
E)  a supposition.

Question 2

Suppose individual robins with longer beaks have somewhat more offspring than those with shorter beaks and this has led to increases in beak length over time.We can say that beak size is associated with the _______ of the robin and that there is _______ selection operating on beak size.

Accepted Answer

A)  fitness; stabilizing 
B)  fitness; directional 
C)  genetic structure; stabilizing 
D)  genetic structure; directional 
E)  genetic structure; disruptive 
A)  fitness; stabilizing 
B)  fitness; directional 
C)  genetic structure; stabilizing 
D)  genetic structure; directional 
E)  genetic structure; disruptive

Question 3

In the northern regions of its range, a species of bird experiences selection for increased size.Farther south, it experiences selection for decreased size.Given some migration across its range, the most likely result is

Accepted Answer

A)  diversifying selection. 
B)  heterozygote advantage. 
C)  homozygote advantage. 
D)  clinal variation. 
E)  Muller's ratchet. 
A)  diversifying selection. 
B)  heterozygote advantage. 
C)  homozygote advantage. 
D)  clinal variation. 
E)  Muller's ratchet.

Question 4

If the effective rate of reproduction of an asexual lineage is 6 per year, what would be the effective rate of reproduction of a lineage that was identical to the asexual lineage in every way, except that it was sexual?

Accepted Answer

A)  0 
B)  3 
C)  6 
D)  9 
E)  12 
A)  0 
B)  3 
C)  6 
D)  9 
E)  12

Question 5

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results.   Assuming the mutation rate remains the same and mutations accumulate linearly, about how many mutations should there be in strain A after 50 generations?

Accepted Answer

A)  50 
B)  150 
C)  300 
D)  590 
E)  700 
A)  50 
B)  150 
C)  300 
D)  590 
E)  700

Question 6

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

Accepted Answer

A)  A decrease in size in the sparrow population 
B)  More seeds that are either considerably smaller or considerably larger than average, with fewer that are 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 size in the sparrow population 
B)  More seeds that are either considerably smaller or considerably larger than average, with fewer that are 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 7

Suppose that a particular species of flowering plant that lives only one year can produce red, pink, or white blossoms, depending on its genotype: AA, Aa, and aa produce, respectively, red, pink, and white blossoms.Biologists studying a population of this species count 300 red-flowering, 600 pink-flowering, and 800 white-flowering plants.In a census in the same area the following year, biologists find a population with 600 red-flowering, 900 pink-flowering, and 1,000 white-flowering plants.Which color has the highest fitness?

Accepted Answer

A)  Red has the highest fitness. 
B)  White has the highest fitness. 
C)  Pink has the highest fitness. 
D)  Pink and white have higher fitnesses than red. 
E)  All colors have equal fitness. 
A)  Red has the highest fitness. 
B)  White has the highest fitness. 
C)  Pink has the highest fitness. 
D)  Pink and white have higher fitnesses than red. 
E)  All colors have equal fitness.

Question 8

If a population is monomorphic for an allele at one locus, the population is _______ for that allele, and the frequency of the allele is _______.

Accepted Answer

A)  homozygous; 1 
B)  fixed; 0.5 
C)  heterozygous; 0 
D)  fixed; 1 
E)  heterozygous; 1 
A)  homozygous; 1 
B)  fixed; 0.5 
C)  heterozygous; 0 
D)  fixed; 1 
E)  heterozygous; 1

Question 9

The numbers of fledged young from female robins of different sizes were assayed and are presented in the table.   Assume that body size is at least partially heritable.Assuming that all other fitness aspects (survival, etc.) are independent of size, this population is most likely experiencing ______ selection, and the population should _______ in size over many generations.

Accepted Answer

A)  directional; increase 
B)  directional; stay the same 
C)  directional; decrease 
D)  stabilizing; increase 
E)  stabilizing; decrease 
A)  directional; increase 
B)  directional; stay the same 
C)  directional; decrease 
D)  stabilizing; increase 
E)  stabilizing; decrease

Question 10

Male earwigs that are DD at a locus have greater success in mating than those that are Dd or dd.Which statement is correct?

Accepted Answer

A)  DD is an allele. 
B)  dd is an allele. 
C)  Dd is a genotype. 
D)  There are two genotypes in this population. 
E)  There are three alleles in this population. 
A)  DD is an allele. 
B)  dd is an allele. 
C)  Dd is a genotype. 
D)  There are two genotypes in this population. 
E)  There are three alleles in this population.

Question 11

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results.   What is the approximate mutation rate per generation for strain A?

Accepted Answer

A)  3 
B)  6 
C)  14 
D)  43 
E)  59 
A)  3 
B)  6 
C)  14 
D)  43 
E)  59

Question 12

Following is a list of loci of a mustard plant and the frequencies of their most common allele, at different points along geographic distances from a minefield.   In which is there evidence of a cline?

Accepted Answer

A)  Only locus A 
B)  Only locus B 
C)  Only locus C 
D)  Both loci A and B 
E)  Both loci B and C 
A)  Only locus A 
B)  Only locus B 
C)  Only locus C 
D)  Both loci A and B 
E)  Both loci B and C

Question 13

The frequency of an allele in a population of Drosophila melanogaster changes haphazardly over time, sometimes going up and sometimes going down.In this population, 17 percent had the allele in 1998 and 30 percent had it in 2016.Biologists found no effect of this allele (versus the other alleles in the population) on any phenotypic trait.What is the best explanation for this pattern?

Accepted Answer

A)  The allele is a neutral allele whose frequency is affected by genetic drift. 
B)  The allele is a neutral allele whose frequency is affected by stabilizing selection. 
C)  The allele is undergoing Muller's ratchet. 
D)  The allele is experiencing frequency-dependent selection, and its frequency should decline. 
E)  The allele is experiencing frequency-dependent selection, and its frequency should increase. 
A)  The allele is a neutral allele whose frequency is affected by genetic drift. 
B)  The allele is a neutral allele whose frequency is affected by stabilizing selection. 
C)  The allele is undergoing Muller's ratchet. 
D)  The allele is experiencing frequency-dependent selection, and its frequency should decline. 
E)  The allele is experiencing frequency-dependent selection, and its frequency should increase.

Question 14

In a population of 800 wolves, 320 are CC and 360 are Cc for a locus with two alleles.Which statement is true?

Accepted Answer

A)  The frequency of the C allele is 0.625. 
B)  The frequency of the C allele is 1.25. 
C)  The c allele is more common than the C allele. 
D)  The frequencies of the two alleles add up to 800. 
E)  The frequencies of the two alleles add up to 0.8. 
A)  The frequency of the C allele is 0.625. 
B)  The frequency of the C allele is 1.25. 
C)  The c allele is more common than the C allele. 
D)  The frequencies of the two alleles add up to 800. 
E)  The frequencies of the two alleles add up to 0.8.

Question 15

Diversifying selection is operating on size in a species of barnacles.This means that _______ have the highest fitness and that the variation should _______ over time if size is heritable and if no other forces are operating.

Accepted Answer

A)  only the largest; increase 
B)  only the largest; decrease 
C)  only the smallest; increase 
D)  the largest and the smallest; increase 
E)  the largest and the smallest; decrease 
A)  only the largest; increase 
B)  only the largest; decrease 
C)  only the smallest; increase 
D)  the largest and the smallest; increase 
E)  the largest and the smallest; decrease

Question 16

A population of ocotillo plants has four alleles at the Dopa locus, with allelic frequencies of 0.38, 0.32, 0.19, and 0.11, and the genotype frequencies are roughly consistent with the Hardy-Weinberg equilibrium.This is a description of the genetic _______ of the population.

Accepted Answer

A)  fitness 
B)  structure 
C)  monomorphism 
D)  ratchet 
E)  polymorphism 
A)  fitness 
B)  structure 
C)  monomorphism 
D)  ratchet 
E)  polymorphism

Question 17

The survivorship of individuals from four different populations of a beetle species has been assayed and is presented in the table.TT, TC, and CC represent genotypes at a locus that is important in survival.   Assuming that genotypes at this locus have no other effects on fitness, would we expect variation to be maintained by selection in any of the populations? Why? What would be the expected outcomes in the populations in the absence of any other evolutionary processes?

Accepted Answer

Because the heterozygotes have the highe

Question 18

A1 and A2 are different forms of the same gene.These are thus different

Accepted Answer

A)  phenotypes. 
B)  genotypes. 
C)  gene pools. 
D)  alleles. 
E)  dominant and recessive genes. 
A)  phenotypes. 
B)  genotypes. 
C)  gene pools. 
D)  alleles. 
E)  dominant and recessive genes.

Question 19

Three different alleles (b1, b2, and b3) at the b locus exist in a hypothetical population of juniper trees.If the frequency of b1 is 0.4, what can be said about the frequency of b3?

Accepted Answer

A)  It cannot be less than 0.4. 
B)  It cannot be greater than 0.6. 
C)  It is 0.3. 
D)  It is 0. 
E)  More information is required to answer this question. 
A)  It cannot be less than 0.4. 
B)  It cannot be greater than 0.6. 
C)  It is 0.3. 
D)  It is 0. 
E)  More information is required to answer this question.

Question 20

Deviations from Hardy-Weinberg

Accepted Answer

A)  occur because there are two alleles per genotype. 
B)  occur when evolutionary forces are operating on the population. 
C)  occur when evolutionary forces are not operating on the population. 
D)  only occur in animals. 
E)  cannot occur in natural populations. 
A)  occur because there are two alleles per genotype. 
B)  occur when evolutionary forces are operating on the population. 
C)  occur when evolutionary forces are not operating on the population. 
D)  only occur in animals. 
E)  cannot occur in natural populations.

Exam 20: Mechanisms of Evolution

According to its scientific definition, a theory is

Suppose individual robins with longer beaks have somewhat more offspring than those with shorter beaks and this has led to increases in beak length over time.We can say that beak size is associated with the _______ of the robin and that there is _______ selection operating on beak size.

In the northern regions of its range, a species of bird experiences selection for increased size.Farther south, it experiences selection for decreased size.Given some migration across its range, the most likely result is

If the effective rate of reproduction of an asexual lineage is 6 per year, what would be the effective rate of reproduction of a lineage that was identical to the asexual lineage in every way, except that it was sexual?

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. Assuming the mutation rate remains the same and mutations accumulate linearly, about how many mutations should there be in strain A after 50 generations?

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

If a population is monomorphic for an allele at one locus, the population is _______ for that allele, and the frequency of the allele is _______.

Male earwigs that are DD at a locus have greater success in mating than those that are Dd or dd.Which statement is correct?

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. What is the approximate mutation rate per generation for strain A?

Following is a list of loci of a mustard plant and the frequencies of their most common allele, at different points along geographic distances from a minefield. In which is there evidence of a cline?

In a population of 800 wolves, 320 are CC and 360 are Cc for a locus with two alleles.Which statement is true?

Diversifying selection is operating on size in a species of barnacles.This means that _______ have the highest fitness and that the variation should _______ over time if size is heritable and if no other forces are operating.

A population of ocotillo plants has four alleles at the Dopa locus, with allelic frequencies of 0.38, 0.32, 0.19, and 0.11, and the genotype frequencies are roughly consistent with the Hardy-Weinberg equilibrium.This is a description of the genetic _______ of the population.

A1 and A2 are different forms of the same gene.These are thus different

Three different alleles (b1, b2, and b3) at the b locus exist in a hypothetical population of juniper trees.If the frequency of b1 is 0.4, what can be said about the frequency of b3?

Deviations from Hardy-Weinberg

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Suppose individual robins with longer beaks have somewhat more offspring than those with shorter beaks and this has led to increases in beak length over time.We can say that beak size is associated with the _ of the robin and that there is _ selection operating on beak size.

If a population is monomorphic for an allele at one locus, the population is _ for that allele, and the frequency of the allele is _.

Diversifying selection is operating on size in a species of barnacles.This means that _ have the highest fitness and that the variation should _ over time if size is heritable and if no other forces are operating.