Q: In a population, the frequency of allele A is $$0.7$$ and the frequency of allele a is $$0.3. $$According to Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes (Aa)?

$$2pq = 2 \times 0.7 \times 0.3 = 0.42$$

Question 1

Which of the following best describes the concept of a gene pool?

Accepted Answer

All the genetic information carried by all members of a breeding population.

Question 2

Which mechanism is the only source of entirely new alleles in a population?

Accepted Answer

Mutation

Question 3

A population of birds is separated by a mountain range, preventing them from interbreeding. This is an example of:

Accepted Answer

Reproductive isolation

Question 4

According to the Hardy-Weinberg Law, if $$p is $$the frequency of allele A and $$q is $$the frequency of allele a, which equation must always be true?

Accepted Answer

$$p + q = 1$$

Question 5

Which of the following is an example of the founder effect?

Accepted Answer

A small group of humans colonizes an island, and their descendants have a high frequency of a rare blood type.

Question 6

Which pattern of natural selection favors individuals at both extremes of a phenotypic distribution?

Accepted Answer

Disruptive selection

Question 7

If a population is in Hardy-Weinberg equilibrium, which of the following must be true?

Accepted Answer

Allele frequencies remain constant from generation to generation.

Question 8

A rare genetic disease, Huntington’s chorea, is found at a high frequency in a small, isolated community. Which evolutionary force most likely explains this observation?

Accepted Answer

Genetic drift

Question 9

Which of the following best describes gene flow?

Accepted Answer

The exchange of genetic material between two or more populations.

Question 10

In a population, the frequency of allele A is $$0.7$$ and the frequency of allele a is $$0.3. $$According to Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes (Aa)?

Accepted Answer

$$2pq = 2 	imes 0.7 	imes 0.3 = 0.42$$

Question 11

Which of the following is NOT a condition required for Hardy-Weinberg equilibrium?

Accepted Answer

Small population size

Question 12

A population of insects is exposed to a new pesticide. Over several generations, most individuals become resistant. Which type of selection is most likely occurring?

Accepted Answer

Directional selection

Question 13

Which of the following statements about mutations is correct?

Accepted Answer

Mutations are the only source of new alleles in a population.

Question 14

If a population is highly endogamous, what is the expected effect on genetic variation?

Accepted Answer

Genetic variation will decrease.

Question 15

Which of the following best illustrates stabilizing selection?

Accepted Answer

Human birth weights are most commonly in the middle range, with very low and very high weights having higher mortality.

Question 16

Which of the following is an example of gene flow increasing genetic variation?

Accepted Answer

Individuals from one population migrate and breed with another, introducing new alleles.

Question 17

Which of the following is a correct statement about population genetics?

Accepted Answer

It studies the distribution and change of allele frequencies under the influence of evolutionary processes.

Question 18

A population of 1000 individuals has 360 individuals with genotype AA, 480 with Aa, and 160 with aa. What is the frequency of allele a?

Accepted Answer

$$q = \frac{2 	imes 160 + 480}{2 	imes 1000} = \frac{320 + 480}{2000} = \frac{800}{2000} = 0.4$$

Question 19

Which of the following is most likely to decrease genetic variation within a population?

Accepted Answer

Genetic drift

Question 20

Which of the following best describes the effect of non-random mating on a population?

Accepted Answer

It can increase the frequency of homozygous genotypes.

Genes and Their Evolution: Population Genetics (Chapter 4 Study Notes)

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