Question 1

Which of the following best explains why individuals do NOT evolve, but populations do?

Accepted Answer

Individuals can only pass on the alleles they already possess; only the allele frequencies in a population can change over generations.

Question 2

A population of beetles has two alleles for shell color: G (green, dominant) and g (brown, recessive). If the frequency of the g allele is $$q = 0.3$$, what is the expected frequency of heterozygous beetles under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 2(0.7)(0.3) = 0.42$$

Question 3

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

Accepted Answer

A population of cheetahs is reduced to a few individuals after a disease outbreak, resulting in decreased genetic diversity.

Question 4

Which mechanism of microevolution is the ONLY one that consistently leads to adaptive evolution?

Accepted Answer

Natural selection

Question 5

A population of fish shows a gradual change in body size from north to south along a river. This pattern is best described as:

Accepted Answer

A cline

Question 6

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

Accepted Answer

Small population size

Question 7

In a population, the frequency of a recessive genetic disorder is $$q^2 = 0.0004$. What is the frequency of carriers (heterozygotes) in this population?

Accepted Answer

$$2pq = 2(0.98)(0.02) = 0.0392$$

Question 8

Which of the following best illustrates frequency-dependent selection?

Accepted Answer

A rare left-mouthed form of a fish has a feeding advantage until it becomes common, at which point the right-mouthed form becomes more successful.

Question 9

Which of the following is an example of gene flow increasing the fitness of a population?

Accepted Answer

Mosquitoes acquire insecticide-resistance alleles from neighboring populations, allowing them to survive pesticide use.

Question 10

Which of the following statements about mutations is TRUE?

Accepted Answer

Only mutations in gamete-producing cells can be passed to offspring.

Question 11

A population of lizards has a gene with two alleles, A and a. If the frequency of AA is $$0.36$$, Aa is $$0.48$$, and aa is $$0.16$$, is this population in Hardy-Weinberg equilibrium?

Accepted Answer

Yes, because $$p^2 = 0.36$, 2pq = 0.48$, and q^2$ = 0.16$$ add up to 1 and match the expected frequencies.

Question 12

Which of the following is an example of disruptive selection?

Accepted Answer

A population of birds where both very small and very large beaks are favored, but medium-sized beaks are selected against.

Question 13

Which of the following best describes the founder effect?

Accepted Answer

A small group of individuals starts a new population with a gene pool that differs from the original population.

Question 14

Why does diploidy help preserve genetic variation in a population?

Accepted Answer

Recessive alleles can be hidden in heterozygotes, preventing their elimination by natural selection.

Question 15

Which of the following is an example of heterozygote advantage?

Accepted Answer

Individuals heterozygous for the sickle-cell allele are more resistant to malaria than either homozygote.

Question 16

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

Accepted Answer

Natural selection can create entirely new traits from scratch.

Question 17

A population of insects is exposed to a new pesticide. After several generations, most individuals are resistant. Which mechanism best explains this change?

Accepted Answer

Natural selection increased the frequency of resistance alleles.

Question 18

Which of the following is an example of sexual dimorphism caused by sexual selection?

Accepted Answer

Male peacocks have large, colorful tails, while females are brown and less showy.

Question 19

Which of the following best describes neutral variation?

Accepted Answer

Genetic variation that does not affect an organism's fitness.

Question 20

Which of the following processes is most likely to reduce genetic variation in a small population?

Accepted Answer

Genetic drift

Chapter 23: Evolution of Populations – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards