Q: A population of 1,000 iguanas has two alleles for a gene: A and a. If the frequency of allele A is $$p = 0.7$$ and allele a is $$q = 0.3$$, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

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

Q: A population of 500 individuals has 90 with genotype AA, 320 with Aa, and 90 with aa. What is the frequency of allele a?

$$q = \frac{2 \times 90 + 320}{2 \times 500} = \frac{180 + 320}{1000} = 0.5$$

Question 1

Which of the following best describes Darwin’s phrase 'descent with modification'?

Accepted Answer

All life is connected by common ancestry, and descendants accumulate adaptations over time.

Question 2

Which of the following is NOT a requirement for a population to be in Hardy-Weinberg equilibrium?

Accepted Answer

Small population size

Question 3

A population of 1,000 iguanas has two alleles for a gene: A and a. If the frequency of allele A is $$p = 0.7$$ and allele a is $$q = 0.3$$, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

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

Question 4

Which of the following is the ultimate (original) source of genetic variation in populations?

Accepted Answer

Mutation

Question 5

Why can’t an individual organism evolve?

Accepted Answer

Evolution is a change in allele frequencies in a population, not in individuals.

Question 6

Which of the following is an example of a vestigial structure?

Accepted Answer

The human appendix

Question 7

A population of beetles is exposed to a new pesticide. After several generations, most beetles are resistant. Which statement best explains this observation?

Accepted Answer

Beetles with natural resistance survived and reproduced, increasing the frequency of resistance alleles.

Question 8

Which mechanism of microevolution is most likely to increase genetic differences between two populations?

Accepted Answer

Genetic drift

Question 9

Which type of natural selection favors individuals at both extremes of a phenotypic range?

Accepted Answer

Disruptive selection

Question 10

Why does diploidy help preserve genetic variation in a population?

Accepted Answer

It allows recessive alleles to be hidden from selection in heterozygotes.

Question 11

Which of the following best describes the bottleneck effect?

Accepted Answer

A population is greatly reduced, leading to a loss of genetic diversity.

Question 12

Which of the following is a real-world example of directional selection?

Accepted Answer

The increase in average beak size in a finch population after a drought

Question 13

Which of the following is NOT a reason why natural selection cannot produce perfect organisms?

Accepted Answer

Natural selection creates new alleles on demand.

Question 14

Which of the following is an example of intersexual selection?

Accepted Answer

Female birds choosing mates based on bright plumage

Question 15

A population of 500 individuals has 90 with genotype AA, 320 with Aa, and 90 with aa. What is the frequency of allele a?

Accepted Answer

$$q = \frac{2 	imes 90 + 320}{2 	imes 500} = \frac{180 + 320}{1000} = 0.5$$

Question 16

Which of the following best explains why antibiotic resistance is a growing public health concern?

Accepted Answer

Antibiotics select for bacteria that are already resistant, increasing their frequency.

Question 17

Which of the following is an example of balancing selection?

Accepted Answer

Heterozygote advantage in sickle-cell anemia

Question 18

Which of the following is a correct application of the Hardy-Weinberg equation $$p^2 + 2pq$$ + $$q^2 = 1$?

Accepted Answer

To estimate the frequency of carriers for a recessive genetic disease

Question 19

Which of the following is a molecular homology that supports the theory of evolution?

Accepted Answer

Similar DNA sequences in whales and hippos

Question 20

Which of the following best describes relative fitness in evolutionary biology?

Accepted Answer

The ability of an individual to survive and reproduce compared to others in the population

How Populations Evolve: Mechanisms and Evidence of Evolution

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