Q: In a population, the frequency of a recessive allele (q) for a genetic disorder is $$0.01. $$What percentage of the population are expected to be carriers (heterozygotes) under Hardy-Weinberg equilibrium?

$$2pq = 2 \times 0.99 \times 0.01 = 0.0198 or$$ $$1.98\%$$

Question 1

Which of the following best describes microevolution?

Accepted Answer

The change in allele frequencies in a population over generations

Question 2

A population of 500 wildflowers has 320 red (CRCR), 160 pink (CRCW), and 20 white (CWCW) individuals. What is the frequency of the CR allele?

Accepted Answer

$$0.8$$

Question 3

Which mechanism of evolution is most likely responsible for a population of birds on an island having different allele frequencies than the mainland population due to a few individuals being blown to the island by a storm?

Accepted Answer

Founder effect

Question 4

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

Accepted Answer

Small population size

Question 5

In a population, the frequency of a recessive allele (q) for a genetic disorder is $$0.01. $$What percentage of the population are expected to be carriers (heterozygotes) under Hardy-Weinberg equilibrium?

Accepted Answer

$$2pq = 2 	imes 0.99 	imes 0.01 = 0.0198 or$$ $$1.98\%$$

Question 6

Which of the following best explains why genetic drift has a greater impact on small populations?

Accepted Answer

Chance events can cause allele frequencies to fluctuate more unpredictably

Question 7

A population of insects is exposed to an insecticide. Over time, the frequency of an allele conferring resistance increases. Which evolutionary mechanism is primarily responsible for this change?

Accepted Answer

Natural selection

Question 8

Which of the following is an example of balancing selection?

Accepted Answer

Heterozygote advantage in sickle-cell anemia in malaria-endemic regions

Question 9

Which process is most likely to reduce genetic variation within a population?

Accepted Answer

Genetic drift

Question 10

A population of snakes on an island has a high frequency of unbanded individuals, while the mainland population is mostly banded. Ongoing migration from the mainland introduces banded alleles to the island. What is the evolutionary consequence of this gene flow?

Accepted Answer

It maintains disadvantageous alleles for banding on the island

Question 11

Which of the following equations represents the Hardy-Weinberg equilibrium for a gene with two alleles?

Accepted Answer

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

Question 12

Which of the following is an example of disruptive selection?

Accepted Answer

Selection favors both very light and very dark fur color in a population of mice, but not intermediate colors

Question 13

Why can harmful recessive alleles persist in a population?

Accepted Answer

They can be hidden from selection in heterozygous individuals

Question 14

Which of the following is a real-world example of heterozygote advantage?

Accepted Answer

Individuals heterozygous for the sickle-cell allele are more likely to survive malaria

Question 15

Which of the following statements about mutation is correct?

Accepted Answer

Most mutations that alter phenotype are at least slightly harmful

Question 16

Which of the following best describes the effect of gene flow on populations?

Accepted Answer

It tends to reduce genetic differences between populations

Question 17

Which of the following is an example of sexual selection?

Accepted Answer

Male peacocks with larger, more colorful tails are more likely to attract mates

Question 18

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

Accepted Answer

Natural selection can create new alleles as needed

Question 19

A population of prairie chickens experienced a bottleneck event, drastically reducing its size. What was the likely genetic consequence?

Accepted Answer

Reduced genetic variation and increased frequency of harmful alleles

Question 20

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

Accepted Answer

The fitness of left-mouthed and right-mouthed scale-eating fish depends on how common each phenotype is in the population

Chapter 23: The Evolution of Populations – Study Notes

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