Q: In a population of 100 frogs, there are 64 with genotype GG, 32 with genotype Gg, and 4 with genotype gg. What is the frequency of the g allele in this population?

$$\frac{(2 \times 4) + 32}{2 \times 100} = \frac{40}{200} = 0.2$$

Q: If $$p = 0.7$$ and $$q = 0.3 in a $$population at Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes?

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

Q: Tay-Sachs disease is autosomal recessive. Among Ashkenazi Jews, the frequency of Tay-Sachs disease is 1 in 360. What proportion of the population are heterozygous carriers?

$$2pq \approx 2 \times \sqrt{1/360} \times (1 - \sqrt{1/360}) \approx 0.104$$

Q: In a population, the frequency of allele $$A is$$ $$0.8$$ and allele $$a is$$ $$0.2. $$What is the expected proportion of heterozygotes under Hardy-Weinberg equilibrium?

$$2pq = 2 \times 0.8 \times 0.2 = 0.32$$

Question 1

In a population of 100 frogs, there are 64 with genotype GG, 32 with genotype Gg, and 4 with genotype gg. What is the frequency of the g allele in this population?

Accepted Answer

$$\frac{(2 	imes 4) + 32}{2 	imes 100} = \frac{40}{200} = 0.2$$

Question 2

Which of the following is an assumption of the Hardy-Weinberg law?

Accepted Answer

The population is large, randomly mating, and not affected by mutation, migration, or natural selection

Question 3

If $$p = 0.7$$ and $$q = 0.3 in a $$population at Hardy-Weinberg equilibrium, what is the expected frequency of heterozygotes?

Accepted Answer

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

Question 4

A population of 100 cats has 19 all-white individuals. All-white color is dominant. Assuming Hardy-Weinberg equilibrium, what is the frequency of the all-white allele?

Accepted Answer

$$0.10$$

Question 5

Tay-Sachs disease is autosomal recessive. Among Ashkenazi Jews, the frequency of Tay-Sachs disease is 1 in 360. What proportion of the population are heterozygous carriers?

Accepted Answer

$$2pq \approx 2 	imes \sqrt{1/360} 	imes (1 - \sqrt{1/360}) \approx 0.104$$

Question 6

Which evolutionary force is most likely to increase genetic variation within a population?

Accepted Answer

Migration (gene flow)

Question 7

What is the effect of inbreeding on the frequency of homozygotes in a population?

Accepted Answer

It increases the frequency of homozygotes

Question 8

A population undergoes a severe reduction in size due to a natural disaster, then recovers. What is this scenario called, and what is a likely genetic consequence?

Accepted Answer

Bottleneck effect; reduced genetic variation

Question 9

Which of the following best describes the founder effect?

Accepted Answer

A small group establishes a new population with less genetic variation and potentially different allele frequencies than the original population

Question 10

If a population is in Hardy-Weinberg equilibrium and the frequency of allele $$A is$$ $$p = 0.6$$, what is the expected frequency of genotype $$aa$$?

Accepted Answer

$$q^2 = (1$$ - $$0.6)^2 = 0.16$

Question 11

Which of the following is NOT an assumption of the Hardy-Weinberg equilibrium?

Accepted Answer

Natural selection is present

Question 12

In a population, the frequency of allele $$A is$$ $$0.8$$ and allele $$a is$$ $$0.2. $$What is the expected proportion of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 2 	imes 0.8 	imes 0.2 = 0.32$$

Question 13

Which evolutionary force is most likely to cause the fixation or loss of alleles in a small population?

Accepted Answer

Genetic drift

Question 14

What is the effect of recurrent mutation on allelic frequencies in a population?

Accepted Answer

It leads to a stable equilibrium of allele frequencies

Question 15

Which scenario best illustrates overdominance in natural selection?

Accepted Answer

Heterozygotes have higher fitness than either homozygote

Question 16

A population of polar bears has adaptations for cold environments, such as thick blubber and white fur. Which evolutionary force is responsible for these traits?

Accepted Answer

Natural selection

Question 17

If a population is monomorphic for a gene, what is the allele frequency for the single allele?

Accepted Answer

Close to or equal to 1.0

Question 18

Which of the following is a consequence of positive assortative mating?

Accepted Answer

Increase in homozygosity for traits involved in mate choice

Question 19

In a population, the frequency of allele $$A is$$ $$p$$ and allele $$a is$$ $$q. $$According to Hardy-Weinberg equilibrium, what is the sum of all genotype frequencies?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 20

Which evolutionary force is most likely to cause genetic divergence between populations?

Accepted Answer

Genetic drift

Population Genetics: Principles, Calculations, and Evolutionary Forces

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