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Biol 2002 - Evolutionary Mechanisms

Questions and Answers

1.

Which of the following can be expected to consistently result in adaptation? I. genetic drift II. mutation III. natural selection
- A.
  
  III only
- B.
  
  II only
- C.
  
  I only
- D.
  
  I, II and III
Correct Answer
A. III only
2.

Which of the following can generally be expected to increase the genetic diversity of a population? I. genetic drift II. mutation III. natural selection
- A.
  
  I and II
- B.
  
  I only
- C.
  
  II only
- D.
  
  I and III
Correct Answer
C. II only
3.

In the Hardy-Weinberg equation, p^2, 2pq, and q^2 represent _____ frequencies while p and q represent _____ frequencies. The blanks should be filled, respectively, with:
- A.
  
  Allele; genotype
- B.
  
  Allele; phenotype
- C.
  
  Genotype; allele
- D.
  
  Phenotype; allele
Correct Answer
C. Genotype; allele
4.

In a population of 500 fruit flies, 250 are genotype RR, 100 are genotype Rr and 150 are genotype rr. The relative frequencies of the R and r alleles, respectively, in this population are
- A.
  
  0.6 and 0.4
- B.
  
  0.4 and 0.6
- C.
  
  0.5 and 0.5
- D.
  
  Not enough information to determine.
Correct Answer
A. 0.6 and 0.4
5.

In a population of 1,000 plants, 640 are red-flowered and 360 are white-flowered. The red-flowered trait is due to a dominant allele (G) while the white-flowered trait is due to a recessive allele (g). The relative frequencies of the G and g alleles, respectively, in this population are:
- A.
  
  0.4 and 0.6
- B.
  
  0.5 and 0.5
- C.
  
  0.6 and 0.4
- D.
  
  Not enough information to determine.
Correct Answer
D. Not enough information to determine.
6.

Allele frequencies changing within a population over time indicate that _____ is definitely occurring.
- A.
  
  Gene flow
- B.
  
  Evolution
- C.
  
  Natural selection
- D.
  
  Genetic drift
Correct Answer
B. Evolution
7.

One of the assumptions necessary for the Hardy-Weinberg equation to accurately predict the genotype frequencies within a population is often worded as "large population size". Which of the following evolutionary forces is assumed to have only a negligent effect if "large population size" is assumed?
- A.
  
  Mutation
- B.
  
  Gene flow
- C.
  
  Genetic drift
- D.
  
  Natural selection
Correct Answer
C. Genetic drift
8.

A population of crabs feeds on (and kills) mussels. The crabs feed on mussels with the smallest shells (they are quite easy to open) and also mussels with the largest shells (although hard to open, they represent a valuable food resource once opened). Assuming heritable variation in shell size, with respect to selection on shell size in the mussel population, this would likely be an example of
- A.
  
  Sexual selection.
- B.
  
  Stabilizing selection.
- C.
  
  Directional selection.
- D.
  
  Disruptive selection.
Correct Answer
B. Stabilizing selection.
9.

IF we use a standard deck of 52 playing cards to represent a population, and have the red and black cards represent copies of two different alleles in that population, which of the following situations would simulate the effect of gene flow on allele frequencies in a population?
- A.
  
  Using a green marker to color one of the red cards.
- B.
  
  Destroying all of the black cards.
- C.
  
  Randomly removing and throwing away 45 of the cards.
- D.
  
  Moving 10 cards from a separate deck into our deck.
Correct Answer
D. Moving 10 cards from a separate deck into our deck.
10.

When nonrandom mating occurs in a population so that individuals prefer to mate with similar individuals, allele frequencies should...
- A.
  
  Change and heterozygotes will be overrepresented in the population.
- B.
  
  Remain the same, but heterozygotes will be overrepresented in the population.
- C.
  
  Change and homozygotes will be overrepresented in the population.
- D.
  
  Remain the same, but homozygotes will be overrepresented in the population.
Correct Answer
D. Remain the same, but homozygotes will be overrepresented in the population.
11.

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, 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
- A.
  
  Stabilizing selection.
- B.
  
  Frequency-dependent selection.
- C.
  
  Disruptive selection.
- D.
  
  Sexual selection.
Correct Answer
B. Frequency-dependent selection.
12.

The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not marry 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 emetic uniqueness of this population?
- A.
  
  Population bottleneck and Hardy-Weinberg equilibrium.
- B.
  
  Founder effect and genetic drift.
- C.
  
  Sexual selection and inbreeding depression
- D.
  
  Mutation and natural selection
Correct Answer
B. Founder effect and genetic drift.
13.

Scientists experimentally manipulated tail length in male African widow birds, a species in which males normally have tails longer than their bodies. Males with artificially elongated tails attracted many more mates than those with normal or shortened tails. These results best support the operation of ______ selection as an explanation for tail length in males.
- A.
  
  Indirect
- B.
  
  Fitness
- C.
  
  Natural
- D.
  
  Sexual
Correct Answer
D. Sexual
14.

If allele frequencies at a locus are 0.2 and 0.8, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium conditions?
- A.
  
  0.32
- B.
  
  0.16
- C.
  
  0.68
- D.
  
  0.24
Correct Answer
A. 0.32

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Dec 10, 2013

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Lrq 8

Which of the following can be expected to consistently result in adaptation? I. genetic drift II. mutation III. natural selection

Which of the following can generally be expected to increase the genetic diversity of a population? I. genetic drift II. mutation III. natural selection

In the Hardy-Weinberg equation, p^2, 2pq, and q^2 represent _ frequencies while p and q represent _ frequencies. The blanks should be filled, respectively, with:

In a population of 500 fruit flies, 250 are genotype RR, 100 are genotype Rr and 150 are genotype rr. The relative frequencies of the R and r alleles, respectively, in this population are

In a population of 1,000 plants, 640 are red-flowered and 360 are white-flowered. The red-flowered trait is due to a dominant allele (G) while the white-flowered trait is due to a recessive allele (g). The relative frequencies of the G and g alleles, respectively, in this population are:

Allele frequencies changing within a population over time indicate that _____ is definitely occurring.

One of the assumptions necessary for the Hardy-Weinberg equation to accurately predict the genotype frequencies within a population is often worded as "large population size". Which of the following evolutionary forces is assumed to have only a negligent effect if "large population size" is assumed?

IF we use a standard deck of 52 playing cards to represent a population, and have the red and black cards represent copies of two different alleles in that population, which of the following situations would simulate the effect of gene flow on allele frequencies in a population?

When nonrandom mating occurs in a population so that individuals prefer to mate with similar individuals, allele frequencies should...

When imbalances occur in the sex ratio of sexual species that have two sexes (that is, 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

If allele frequencies at a locus are 0.2 and 0.8, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium conditions?