Question 1

In peas,a gene controls flower colour such that R = purple and r = white.In an isolated pea patch,there are 36 purple-flowering plants and 64 white-flowering plants.Assuming Hardy-Weinberg equilibrium,what is the value of q for this population?

Accepted Answer

A)  0) 36
B)  0) 64
C)  0) 75
D)  0) 80 D

Question 2

Use the following information to answer the questions below.
In those parts of equatorial Africa where the malaria parasite is most common,the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.
-Considering the overall human population of the U.S.mainland at the time when the slave trade brought large numbers of people from equatorial Africa,what was primarily acting to change the frequency of the sickle-cell allele in the overall U.S.population?

Accepted Answer

A)  natural selection
B)  gene flow
C)  genetic drift
D)  founder effect
E)  Two of the responses are correct. B

Question 3

Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus

Accepted Answer

A)  the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change.
B)  natural selection, gene flow, and genetic drift are acting equally to change an allele's frequency.
C)  this means that, at this locus, two alleles are present in equal proportions.
D)  the population itself is not evolving, but individuals within the population may be evolving. A

Question 4

Use the following information to answer the questions below.
In those parts of equatorial Africa where the malaria parasite is most common,the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.
-The sickle-cell allele is pleiotropic (i.e.,it affects more than one phenotypic trait).Specifically,this allele affects oxygen delivery to tissues and affects one's susceptibility to malaria.Under conditions of low atmospheric oxygen availability,individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." Such individuals remain less susceptible to malaria.Thus,pleiotropic genes/alleles such as this can help explain why

Accepted Answer

A)  new advantageous alleles do not arise on demand.
B)  evolution is limited by historical constraints.
C)  adaptations are often compromises.
D)  chance events can affect the evolutionary history of populations.

Question 5

There are those who claim that the theory of evolution cannot be true because the apes,which are supposed to be closely related to humans,do not likewise share the same large brains,capacity for complicated speech,and tool-making capability.They reason that if these features are generally beneficial,then the apes should have evolved them as well.Which of these provides the best argument against this misconception?

Accepted Answer

A)  Advantageous alleles do not arise on demand.
B)  A population's evolution is limited by historical constraints.
C)  Adaptations are often compromises.
D)  Evolution can be influenced by environmental change.

Question 6

During breeding season,one should expect female house finches to prefer to mate with males with the brightest red feathers.Which of the following terms are appropriately applied to this situation?

Accepted Answer

A)  sexual selection
B)  mate choice
C)  intersexual selection
D)  Three of the responses are correct.
E)  Two of the responses are correct.

Question 7

Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations,which one most consistently requires a small population as a precondition for its occurrence?

Accepted Answer

A)  mutation
B)  nonrandom mating
C)  genetic drift
D)  natural selection
E)  gene flow

Question 8

Use the following information to answer the questions below.
In those parts of equatorial Africa where the malaria parasite is most common,the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool.
-What should be the proportion of heterozygous individuals in populations that live here?

Accepted Answer

A)  0) 04
B)  0) 16
C)  0) 20
D)  0) 32
E)  0) 80

Question 9

In seedcracker finches from Cameroon,small- and large-billed birds specialize in cracking soft and hard seeds,respectively.If long-term climatic change resulted in all seeds becoming hard,what type of selection would then operate on the finch population?

Accepted Answer

A)  disruptive selection
B)  directional selection
C)  stabilizing selection
D)  No selection would operate because the population is in Hardy-Weinberg equilibrium.

Question 10

The higher the proportion of loci that are "fixed" in a population,the lower is that population's

Accepted Answer

A)  nucleotide variability only.
B)  genetic polyploidy only.
C)  average heterozygosity only.
D)  nucleotide variability, average heterozygosity, and genetic polyploidy.
E)  nucleotide variability and average heterozygosity only.

Question 11

Hardy-Weinberg equilibrium must occur in populations wherein

Accepted Answer

A)  an allele remains fixed.
B)  no genetic variation exists.
C)  natural selection is not operating.
D)  All three of the responses above are correct.
E)  Only two of the responses above are correct.

Question 12

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e.,other than a 50:50 ratio),the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex.This is most clearly an example of

Accepted Answer

A)  sexual selection.
B)  disruptive selection.
C)  balancing selection.
D)  stabilizing selection.
E)  frequency-dependent selection.

Question 13

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s.They do not marry with members outside their own immediate community.Today,the Dunkers are genetically unique and differ in gene frequencies,at many loci,from all other populations including those in their original homeland.Which of the following likely explains the genetic uniqueness of this population?

Accepted Answer

A)  population bottleneck and Hardy-Weinberg equilibrium
B)  heterozygote advantage and stabilizing selection
C)  mutation and natural selection
D)  founder effect and genetic drift
E)  population bottleneck and stabilizing selection

Question 14

Use the following information to answer the questions below.
In the year 2500,five male space colonists and five female space colonists (all unrelated to each other)settle on an uninhabited Earthlike planet in the Andromeda galaxy.The colonists and their offspring randomly mate for generations.All ten of the original colonists had free earlobes,and two were heterozygous for that trait.The allele for free earlobes is dominant to the allele for attached earlobes.
-Which of these is closest to the allele frequency in the founding population?

Accepted Answer

A)  0) 1 a, 0.9 A
B)  0) 2 a, 0.8 A
C)  0) 5 a, 0.5 A
D)  0) 8 a, 0.2 A
E)  0) 4 a, 0.6 A

Question 15

The following questions refer to the following paragraph.
HIV's genome of RNA includes the code for reverse transcriptase (RT),an enzyme that acts early in infection to synthesize a DNA genome from an RNA template.The HIV genome also codes for protease (PR),an enzyme that acts later in infection by cutting long viral polyproteins into smaller,functional proteins.Both RT and PR represent potential targets for antiretroviral drugs.Drugs called nucleoside analogues (NA)act against RT,whereas drugs called protease inhibitors (PI)act against PR.
-Within the body of an HIV-infected individual who is being treated with a single NA,and whose HIV particles are currently vulnerable to this NA,which of these situations can increase the relative fitness of the virus?
1)mutations resulting in RTs with decreased rates of nucleotide mismatch
2)mutations resulting in RTs with increased rates of nucleotide mismatch
3)mutations resulting in RTs that have proofreading capability

Accepted Answer

A)  1 only
B)  2 only
C)  3 only
D)  1 and 3
E)  2 and 3

Question 16

Use this information to answer the following questions
Many species once roamed across large areas of continents,and for millions of years these species were "shaped" by their environment.Today,numerous species,especially large carnivores,are found in national parks and nature reserves that are isolated by hundreds or thousands of kilometres of land now occupied by humans.The cheetah is one example of a species that has shown several dramatic decreases in numbers over time,and now occupies a small fraction of its historic range.
-Which of the following statements would most likely apply to cheetahs currently found in Kenya and South Africa?

Accepted Answer

A)  Certain alleles may be under- or over-represented in cheetah populations.
B)  Cheetah populations likely passed through several bottlenecks, which may have been caused by factors such as disease, competition with other predators, overhunting, poaching, and habitat loss.
C)  Over time, reduced gene flow between the isolated populations would lead to aggressive encounters if the separated populations were brought together.
D)  Natural selection has much more impact on large populations than on small populations.
E)  A and B

Question 17

Arrange the following from most general (i.e.,most inclusive)to most specific (i.e.,least inclusive):
1 natural selection
2)microevolution
3)intrasexual selection
4)evolution
5)sexual selection

Accepted Answer

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

Question 18

Over time,the movement of people on Earth has steadily increased.This has altered the course of human evolution by increasing

Accepted Answer

A)  nonrandom mating.
B)  geographic isolation.
C)  genetic drift.
D)  gene flow.

Question 19

Use this information below to answer the following questions.
A large population of laboratory animals has been allowed to breed randomly for a number of generations.After several generations,25% of the animals display a recessive trait (aa),the same percentage as at the beginning of the breeding program.The rest of the animals show the dominant phenotype,with heterozygotes indistinguishable from the homozygous dominants.
-What proportion of the population is probably heterozygous (Aa)for this trait?

Accepted Answer

A)  0) 05
B)  0) 25
C)  0) 50
D)  0) 75

Question 20

Swine are vulnerable to infection by bird flu virus and human flu virus,which can both be present in an individual pig at the same time.When this occurs,it is possible for genes from bird flu virus and human flu virus to be combined.If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug)to the new virus,and if the new virus is introduced to an environment lacking Tamiflu,then what is most likely to occur?

Accepted Answer

A)  The new virus will maintain its Tamiflu-resistance gene, just in case of future exposure to Tamiflu.
B)  The Tamiflu-resistance gene will undergo mutations that convert it into a gene that has a useful function in this environment.
C)  If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.
D)  If the Tamiflu-resistance gene confers no benefit in the current environment, and has no cost, the virus will become dormant until Tamiflu is present.

Exam 23: The Evolution of Populations