Q: A population of 100 individuals has the following genotype counts for a gene with two alleles (G and g): 36 GG, 48 Gg, and 16 gg. What is the frequency of the G allele ($$p$$)?

$$p = \frac{2(36) + 48}{2 \times 100} = 0.6$$

Q: A rare recessive disease occurs in 1 out of 2,000 individuals in a population. Assuming Hardy-Weinberg equilibrium, what is the expected carrier frequency?

$$2pq = 2 \times 0.022 \times 0.978 = 0.0437$$

Q: A population has three alleles for a gene: $$A$$, $$B$$, and $$O$$, with frequencies $$p = 0.23$$, $$q = 0.09$$, and $$r = 0.68. $$What is the expected frequency of genotype $$AO$$ under Hardy-Weinberg equilibrium?

$$2pr = 2 \times 0.23 \times 0.68 = 0.313$$

Question 1

Which of the following best defines evolution in the context of population genetics?

Accepted Answer

The change in genetic variation (e.g., allele frequencies) in a population over time.

Question 2

A population of 100 individuals has the following genotype counts for a gene with two alleles (G and g): 36 GG, 48 Gg, and 16 gg. What is the frequency of the G allele ($$p$$)?

Accepted Answer

$$p = \frac{2(36) + 48}{2 	imes 100} = 0.6$$

Question 3

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

Accepted Answer

Population size is finite

Question 4

In a population in Hardy-Weinberg equilibrium with two alleles, $$p$$ and $$q$$, what is the expected frequency of heterozygotes?

Accepted Answer

$$2pq$$

Question 5

A rare recessive disease occurs in 1 out of 2,000 individuals in a population. Assuming Hardy-Weinberg equilibrium, what is the expected carrier frequency?

Accepted Answer

$$2pq = 2 	imes 0.022 	imes 0.978 = 0.0437$$

Question 6

Which of the following statements about random mating is correct?

Accepted Answer

Random mating does not change allele frequencies but can change genotype frequencies.

Question 7

Which type of non-random mating increases the frequency of homozygotes in a population?

Accepted Answer

Inbreeding

Question 8

If a population experiences a bottleneck, what is the most likely genetic consequence?

Accepted Answer

Reduction in genetic variation

Question 9

Which of the following best describes the effect of genetic drift?

Accepted Answer

It is stronger in small populations and can lead to fixation or loss of alleles.

Question 10

A population has three alleles for a gene: $$A$$, $$B$$, and $$O$$, with frequencies $$p = 0.23$$, $$q = 0.09$$, and $$r = 0.68. $$What is the expected frequency of genotype $$AO$$ under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pr = 2 	imes 0.23 	imes 0.68 = 0.313$$

Question 11

Which of the following scenarios would violate the Hardy-Weinberg assumption of infinite population size?

Accepted Answer

A population of 10 individuals experiencing random sampling each generation

Question 12

Which of the following is a real-world example of a founder effect?

Accepted Answer

A small group of individuals establishes a new population, leading to Ellis-van Creveld syndrome being more common in that group.

Question 13

Which type of assortative mating increases heterozygosity at the genomic region responsible for the trait?

Accepted Answer

Negative assortative mating

Question 14

Why does it take longer for X-linked genes to reach Hardy-Weinberg equilibrium compared to autosomal genes?

Accepted Answer

Because allele frequencies in males and females must equilibrate over several generations

Question 15

Which of the following is true about mutation in the context of population genetics?

Accepted Answer

Mutation introduces new alleles but does not dramatically affect allele frequencies in the short term.

Question 16

A population is in Hardy-Weinberg equilibrium with $$p = 0.6$$ and $$q = 0.4. $$What is the expected frequency of homozygous recessive individuals?

Accepted Answer

$$q^2 = 0.16$

Question 17

Which of the following evolutionary forces can cause allele frequencies to change between two populations?

Accepted Answer

Migration

Question 18

Inbreeding increases the risk of recessive genetic diseases because:

Accepted Answer

It increases the frequency of homozygotes, including those for deleterious alleles.

Question 19

Which of the following best describes the effect of a population bottleneck?

Accepted Answer

It reduces genetic variation due to non-representative sampling of alleles.

Question 20

If the frequency of allele $$A is$$ $$p = 0.7$$ and allele $$a is$$ $$q = 0.3 in a $$large, randomly mating population, what is the expected frequency of genotype $$Aa$$ under Hardy-Weinberg equilibrium?

Accepted Answer

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

CHAPTER 20A

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