Question 1

Which of the following best describes microevolution?

Accepted Answer

The change in allele frequencies within a population over time.

Question 2

Which process is the original source of all genetic variation in populations?

Accepted Answer

Mutation

Question 3

A population of beetles is exposed to a new pesticide. Over several generations, the frequency of an allele conferring resistance increases. Which evolutionary process is primarily responsible for this change?

Accepted Answer

Natural selection

Question 4

Which of the following scenarios best illustrates genetic drift?

Accepted Answer

A small group of birds migrates to a new island, and the allele frequencies in the new population differ from the original.

Question 5

Which equation represents the calculation of allele frequency for allele A in a population, given $$n_A$$ copies of allele A and $$N$$ total alleles?

Accepted Answer

$$f_A = \frac{n_A}{N}$$

Question 6

Which of the following is NOT a way that sexual reproduction increases genetic variation in a population?

Accepted Answer

Replication of DNA without error

Question 7

A population of fish in a lake is split into two by a drought, creating two isolated ponds. Over time, the allele frequencies in the two populations diverge. Which process is most likely responsible for this divergence?

Accepted Answer

Genetic drift

Question 8

Which of the following statements about natural selection is TRUE?

Accepted Answer

Natural selection acts only on heritable genetic variation.

Question 9

In a population, the sickle cell allele (S) is maintained at a relatively high frequency in regions where malaria is common. This is an example of:

Accepted Answer

Heterozygote advantage

Question 10

Which of the following best describes the bottleneck effect?

Accepted Answer

A population is drastically reduced in size due to a random event, resulting in loss of genetic diversity.

Question 11

Which evolutionary process can counteract the effects of genetic drift by introducing new alleles into a population?

Accepted Answer

Gene flow

Question 12

Which of the following is an example of negative frequency-dependent selection?

Accepted Answer

Rare scale-eating fish phenotypes have higher fitness than common ones, maintaining both phenotypes in the population.

Question 13

Which type of selection reduces genetic variation by favoring intermediate phenotypes and removing extremes?

Accepted Answer

Stabilizing selection

Question 14

A population of prairie chickens experienced a severe reduction in numbers due to habitat loss, resulting in decreased genetic diversity and fertility. This is an example of:

Accepted Answer

Bottleneck effect

Question 15

Which of the following is TRUE regarding mutations in multicellular eukaryotes?

Accepted Answer

Mutations in germ-line cells are heritable and contribute to genetic variation.

Question 16

Which process is most likely to maintain genetic diversity in a population over time?

Accepted Answer

Balancing selection

Question 17

Which of the following is a consequence of genome duplications?

Accepted Answer

Increase in genome complexity and potential for evolutionary innovation.

Question 18

Which of the following is NOT a limitation of natural selection?

Accepted Answer

Natural selection guarantees species survival.

Question 19

If a population has two alleles, A and a, with frequencies $$p$$ and $$q$$ respectively, what is the expected frequency of heterozygotes under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq$$

Question 20

Which evolutionary process is most likely to cause populations to become more genetically similar (homogenized) over time?

Accepted Answer

Gene flow

Question 21

Which of the following best explains why rare alleles are more likely to be lost in small populations?

Accepted Answer

Genetic drift causes random fluctuations in allele frequencies, which have a larger impact in small populations.

Microevolution and Genetic Variation in Populations

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