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

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

Question 1

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

Accepted Answer

Mutations occur at a high rate in the population.

Question 2

In a population of 1000 individuals, 360 show the recessive phenotype for a trait controlled by a single gene with two alleles. Assuming Hardy-Weinberg equilibrium, what is the frequency of the dominant allele?

Accepted Answer

$$q^2$$ = \frac{360}{1000} = 0.36 \implies q = 0.6$$, so p = 1 - 0.6 = 0.4$

Question 3

Which scenario best illustrates genetic drift?

Accepted Answer

A disease wipes out most of a small population, leaving only a few survivors with different allele frequencies than the original population.

Question 4

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 5

Which of the following would most likely disrupt Hardy-Weinberg equilibrium in a population?

Accepted Answer

Natural selection favoring one allele over another.

Question 6

A population of mice has two alleles for fur color: B (black, dominant) and b (white, recessive). If 16% of the mice are white, what is the frequency of the B allele?

Accepted Answer

$$q^2 = 0.16$$ \implies q = 0.4$$, so p = 1 - 0.4 = 0.6$

Question 7

Which of the following best describes gene flow?

Accepted Answer

The movement of alleles into or out of a population due to migration.

Question 8

A small group of birds is blown by a storm to a new island, where they establish a new population. Over time, the allele frequencies in this new population differ from the original. This is an example of:

Accepted Answer

Founder effect

Question 9

If a population is in Hardy-Weinberg equilibrium and the frequency of the dominant allele is 0.8, what is the expected frequency of homozygous recessive individuals?

Accepted Answer

$$q = 1 - 0.8 = 0.2$$, so $$q^2 = 0.04$

Question 10

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

Accepted Answer

A population of cheetahs is reduced to a few individuals due to habitat loss, resulting in reduced genetic diversity.

Question 11

Which of the following best defines a genotype?

Accepted Answer

The allele combination producing the phenotype.

Question 12

In a population, the frequency of allele A is 0.5 and allele a is 0.5. What is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 2 	imes 0.5 	imes 0.5 = 0.5$$

Question 13

Which of the following would NOT cause a change in allele frequency in a population?

Accepted Answer

Random mating

Question 14

A population of 200 individuals has the following genotype counts: 98 AA, 84 Aa, and 18 aa. What is the frequency of allele a?

Accepted Answer

$$q = \frac{2 	imes 18 + 84}{2 	imes 200} = \frac{36 + 84}{400} = \frac{120}{400} = 0.3$$

Question 15

Which of the following statements about alleles is correct?

Accepted Answer

Alleles are different forms of a gene that may produce different phenotypes.

Question 16

A population of flowers has two alleles for color: R (red) and r (white). If 49% of the flowers are white, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

$$q^2 = 0.49$$ \implies q = 0.7$$, p = 0.3$, 2pq = 2$$ 	imes 0.3 	imes 0.7 = 0.42$$

Question 17

Which of the following is an example of natural selection affecting allele frequencies?

Accepted Answer

Predators preferentially eat light-colored mice, increasing the frequency of the dark allele.

Question 18

If a population is not in Hardy-Weinberg equilibrium, which of the following could be a reason?

Accepted Answer

There is non-random mating.

Question 19

Which of the following best describes the phenotype?

Accepted Answer

The physical appearance of a trait, such as hair color.

Question 20

A population of beetles is reduced from 1000 to 10 individuals by a flood. The surviving beetles have a different allele frequency than the original population. This is an example of:

Accepted Answer

Bottleneck effect

Population Genetics and the Hardy-Weinberg Equilibrium

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