Q: In a population, the frequency of allele A is 0.7 and allele a is 0.3. What is the expected frequency of heterozygotes (Aa) under Hardy–Weinberg equilibrium?

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

Q: A population of 50 mice has two coat colors: agouti (dominant) and white (recessive). The frequency of the agouti allele is 0.4 and the white allele is 0.6. How many mice are expected to be heterozygous for this gene?

$$2 \times 0.4 \times 0.6 \times 50 = 24$$

Q: In a population, the observed genotype frequencies for a gene are: AA = 0.36, Aa = 0.48, aa = 0.16. What are the allele frequencies for A and a?

A: $$0.36 + 0.5 \times 0.48 = 0.6$$, a: $$0.16 + 0.5 \times 0.48 = 0.4$$

Question 1

Which of the following best defines a gene pool in the context of population genetics?

Accepted Answer

The collection of all alleles present in the members of a population.

Question 2

A population of beetles has the same shell color, but their DNA sequences differ at several genes. What does this indicate about genetic variation?

Accepted Answer

Populations can differ genetically while appearing the same.

Question 3

Which of the following is a source of genetic polymorphism in a population?

Accepted Answer

Mutation in the DNA sequence of a gene.

Question 4

In a population, the frequency of allele A is 0.7 and allele a is 0.3. What is the expected frequency of heterozygotes (Aa) under Hardy–Weinberg equilibrium?

Accepted Answer

$$2 	imes 0.7 	imes 0.3 = 0.42$$

Question 5

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

Accepted Answer

There is natural selection favoring certain alleles.

Question 6

If a population is in Hardy–Weinberg equilibrium, what does this imply about the evolutionary forces acting on the population?

Accepted Answer

No evolutionary forces are acting on the population at that locus.

Question 7

A population of 50 mice has two coat colors: agouti (dominant) and white (recessive). The frequency of the agouti allele is 0.4 and the white allele is 0.6. How many mice are expected to be heterozygous for this gene?

Accepted Answer

$$2 	imes 0.4 	imes 0.6 	imes 50 = 24$$

Question 8

Which of the following best describes a neutral polymorphism?

Accepted Answer

A DNA sequence change that does not affect the phenotype.

Question 9

If the frequency of allele A in a population is $$p$$ and the frequency of allele a is $$q$$, which equation correctly represents the expected genotype frequencies under Hardy–Weinberg equilibrium?

Accepted Answer

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

Question 10

In a population, the observed genotype frequencies for a gene are: AA = 0.36, Aa = 0.48, aa = 0.16. What are the allele frequencies for A and a?

Accepted Answer

A: $$0.36 + 0.5 	imes 0.48 = 0.6$$, a: $$0.16 + 0.5 	imes 0.48 = 0.4$$

Question 11

Which scenario would most likely cause a population to deviate from Hardy–Weinberg equilibrium?

Accepted Answer

A small population where genetic drift is significant.

Question 12

Why is the frequency of heterozygotes (2pq) highest when $$p = q = 0.5$$?

Accepted Answer

Because $$2pq$$ reaches its maximum value when both alleles are equally frequent.

Question 13

A mutation in the Adh gene of Drosophila results in a new allele that does not change the amino acid sequence. What is the most likely effect of this mutation?

Accepted Answer

It is a neutral polymorphism and likely has no effect on phenotype.

Question 14

If a population starts with genotype frequencies AA = 0.49, Aa = 0.42, aa = 0.09, and random mating occurs, what will the genotype frequencies be in the next generation?

Accepted Answer

AA = 0.49, Aa = 0.42, aa = 0.09

Question 15

Which of the following best explains why most genetic variation is not visible in the phenotype?

Accepted Answer

Many genetic differences occur in non-coding regions or do not affect protein function.

Question 16

A population of 100 individuals has the following genotype counts for a gene: AA = 36, Aa = 48, aa = 16. What is the frequency of allele a?

Accepted Answer

$$(2 	imes 16 + 48) / (2 	imes 100) = 0.4$$

Question 17

Which of the following is a real-world example of natural selection acting on genetic variation?

Accepted Answer

The change in frequency of dark and light forms of the peppered moth during the Industrial Revolution.

Genetic Variation of Populations and the Hardy–Weinberg Principle

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