Question 1

The graph shows the range of variation among population members for a trait determined by multiple genes.  If this population were subject to stabilizing selection for several generations, which, if any, of the distributions shown would be most likely to result?

Accepted Answer

A)  a 
B)  b 
C)  c 
D)  d 
E)  None of the above; there would be no change.

Question 2

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results.  Is strain C accumulating mutations at roughly a linear rate? If yes, what is the rate? If no, is the accumulation faster or slower than linear?

Accepted Answer

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

Question 3

In a population of hamsters, some individuals have the nucleotide G at a locus and some have the nucleotide A.Stating that an individual has copies of both G and A characterizes that individual's _______, and that individual is a _______.

Accepted Answer

A)  gene pool; heterozygote 
B)  gene pool; homozygote 
C)  genotype; heterozygote 
D)  genotype; homozygote 
E)  allele frequency; heterozygote

Question 4

A normally asexual lineage experiences sexual reproduction, and as a result the amount of genetic variation increases and deleterious mutations are purged from the lineage.This purging is a reversal of

Accepted Answer

A)  directional selection. 
B)  disruptive selection. 
C)  heterozygote advantage. 
D)  trade-offs. 
E)  Muller's ratchet.

Question 5

Male whitetail deer produce antlers every year and then shed them after the breeding season.Discuss the trade-offs in this cycle.

Accepted Answer

The answer of Male whitetail deer produce antlers every year...

Question 6

Which mode(s) of selection result(s) in a decrease in variation?

Accepted Answer

A)  Stabilizing selection only 
B)  Directional selection only 
C)  Disruptive selection only 
D)  Both stabilizing and disruptive selection 
E)  Both directional and stabilizing selection

Question 7

A population of mice has been monitored for change over several generations.Following are five different bones and the changes to their means and extents of variation. Tibia: Mean increased 0.14 units; variation decreased.
Femur: Mean increased 0.08 units; variation increased.
Ulna: Mean did not change; variation increased.
Clavicle: Mean did not change; variation decreased.
Radius: Mean decreased 0.12 units; variation decreased.
Which is most likely to be under stabilizing selection?

Accepted Answer

A)  Tibia 
B)  Femur 
C)  Ulna 
D)  Clavicle 
E)  Radius

Question 8

Suppose in a population of 250,000 mice the mutation rate per nucleotide for a genetic locus is 4 × 10-8.The locus contains 1,500 nucleotides.How many new mutations should we expect at this locus in each generation?

Accepted Answer

A)  3 
B)  10 
C)  15 
D)  20 
E)  30

Question 9

In a haploid bacterium, 720 of 900 individuals have the c1 allele.What is the frequency of the c1allele?

Accepted Answer

A)  0.4 
B)  0.72 
C)  0.8 
D)  0.9 
E)  1.6

Question 10

If the frequency of one allele at a locus with two alleles is 0.73, the frequency of the other allele must be _______.

Accepted Answer

The answer of If the frequency of one allele at...

Question 11

Suppose variants at a single locus affect wing length in a species of crickets, with homozygotes for the L allele having long wings, homozygotes for the l allele having short wings, and heterozygotes having wings of intermediate length.In one population of 600 individuals, 400 have long wings, 160 have intermediate-length wings, and 40 have short wings.Is there an excess or a deficiency of heterozygotes in the population with respect to Hardy-Weinberg equilibrium? By how many individuals?

Accepted Answer

A)  An excess of 64 individuals 
B)  An excess of 32 individuals 
C)  An excess of 16 individuals 
D)  A deficiency of 16 individuals 
E)  A deficiency of 32 individuals

Question 12

Height in humans is influenced by numerous loci and has a relatively smooth distribution.It is thus a _______ or _______ trait.

Accepted Answer

A)  quantitative; discrete 
B)  quantitative; continuous 
C)  qualitative; continuous 
D)  qualitative; discrete 
E)  qualitative; heritable

Question 13

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.

Accepted Answer

The answer of The numbers of fledged young from female...

Question 14

In Mendel's peas, tall and short plant variants resulted from differences at a single genetic locus, with tall being dominant to short.The height of the plant is called its

Accepted Answer

A)  allele. 
B)  gene pool. 
C)  phenotype. 
D)  genotype. 
E)  adaptation.

Question 15

A cricket has a diploid genome of 1.2 billion bp.Assume that there are about 200,000 individuals in the population and that the mutation rate is 1 per 100 million bp.About how many new mutations will occur in each generation of the population of crickets?

Accepted Answer

A)  1.2 
B)  12 
C)  200,000 
D)  1 million 
E)  2.4 million

Question 16

Refer to the figure.  Suppose an experiment like that of Malte Andersson were repeated in a different population of widowbirds, and the results shown were obtained.What inferences would you draw from these results? Would sexual selection still be operating?

Accepted Answer

The answer of Refer to the figure.  Suppose an...

Question 17

The differential contribution of offspring to the next generation by various genetic types belonging to the original population is known as _______.

Accepted Answer

The answer of The differential contribution of offspring to the...

Question 18

If there is only one allele at a locus in a particular population, that allele is said to be fixed and the locus is _______.

Accepted Answer

The answer of If there is only one allele at...

Question 19

In several species of insects, males with large testes often have better mating success but take longer to develop than those with small testes.Such a pattern is an example of a(n) _______.

Accepted Answer

The answer of In several species of insects, males with...

Question 20

The observation that females of a species of beetles prefer to mate with males with relatively rare color patterns would be an illustration of

Accepted Answer

A)  Muller's ratchet. 
B)  genetic drift. 
C)  the founder effect. 
D)  frequency-dependent selection. 
E)  disruptive selection.

Exam 20: Mechanisms of Evolution

The graph shows the range of variation among population members for a trait determined by multiple genes. If this population were subject to stabilizing selection for several generations, which, if any, of the distributions shown would be most likely to result?

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. Is strain C accumulating mutations at roughly a linear rate? If yes, what is the rate? If no, is the accumulation faster or slower than linear?

In a population of hamsters, some individuals have the nucleotide G at a locus and some have the nucleotide A.Stating that an individual has copies of both G and A characterizes that individual's _, and that individual is a _.