Q: A population of 100 individuals has 36 AA, 48 Aa, and 16 aa. What is the frequency of the a allele?

$$f(a) = \frac{(2 \times 16) + 48}{200} = 0.4$$

Q: A population of 200 moths has 160 black (BB), 35 gray (Bb), and 5 white (bb) individuals. What is the frequency of the b allele?

$$f(b) = \frac{(2 \times 5) + 35}{400} = 0.1125$$

Question 1

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

Accepted Answer

All the alleles present in a population.

Question 2

A population of 100 individuals has 36 AA, 48 Aa, and 16 aa. What is the frequency of the a allele?

Accepted Answer

$$f(a) = \frac{(2 	imes 16) + 48}{200} = 0.4$$

Question 3

Which evolutionary force is most likely to cause a rapid loss of genetic variation after a natural disaster drastically reduces population size?

Accepted Answer

Genetic drift (bottleneck effect)

Question 4

In a population at Hardy-Weinberg equilibrium, if the frequency of the recessive phenotype (aa) is 0.25, what is the frequency of the dominant allele (A)?

Accepted Answer

$$q^2 = 0.25$$ \Rightarrow q = 0.5;\ p = 1 - 0.5 = 0.5$$

Question 5

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

Accepted Answer

Small population size

Question 6

A rare allele is introduced into a population by migration. Which evolutionary force is responsible for this change?

Accepted Answer

Gene flow

Question 7

In a population, 36% of individuals show the recessive trait (aa). What are the expected genotype frequencies under Hardy-Weinberg equilibrium?

Accepted Answer

$$q^2 = 0.36$$ \Rightarrow q = 0.6;\ p = 0.4;\ $$p^2 = 0.16$$;\ 2pq = 0.48;\ $$q^2 = 0.36$

Question 8

Which type of natural selection increases the frequency of individuals with average phenotypes and reduces variation?

Accepted Answer

Stabilizing selection

Question 9

A small group of individuals founds a new population, and their allele frequencies differ from the original population. This is an example of:

Accepted Answer

Founder effect

Question 10

Why is genetic drift more significant in small populations than in large populations?

Accepted Answer

Random fluctuations in allele frequencies have a greater impact when there are fewer individuals.

Question 11

Which real-world scenario best illustrates the bottleneck effect?

Accepted Answer

A cheetah population is reduced to a few individuals after a disease outbreak, resulting in low genetic diversity.

Question 12

If $$p = 0.7$$ for allele A in a population, what is the frequency of allele a?

Accepted Answer

$$q = 1 - 0.7 = 0.3$$

Question 13

Which of the following best explains why gene flow can decrease genetic differences between populations?

Accepted Answer

Gene flow introduces alleles from one population to another, making their gene pools more similar.

Question 14

A population of 200 moths has 160 black (BB), 35 gray (Bb), and 5 white (bb) individuals. What is the frequency of the b allele?

Accepted Answer

$$f(b) = \frac{(2 	imes 5) + 35}{400} = 0.1125$$

Question 15

Which of the following is a direct application of population genetics in agriculture?

Accepted Answer

Breeding programs to increase resistance traits in crops.

Question 16

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

Accepted Answer

There is nonrandom mating occurring in the population.

Question 17

Which equation correctly represents the expected genotype frequencies under Hardy-Weinberg equilibrium for two alleles, A and a?

Accepted Answer

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

Question 18

A disease allele is found at a frequency of 0.01 in a large, randomly mating human population. What is the expected frequency of carriers (heterozygotes) under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 2 	imes 0.99 	imes 0.01 = 0.0198$$

Question 19

Which of the following scenarios best illustrates directional selection?

Accepted Answer

A population of bacteria exposed to antibiotics shifts toward higher resistance over generations.

Question 20

Why is mutation considered essential for long-term evolution, even though it is rare?

Accepted Answer

It is the ultimate source of new alleles in a population.

Population Genetics: Principles, Forces, and Applications

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