Q: In a population, the frequency of allele $A$ is $0.7$ and allele $a$ is $0.3$. What is the expected frequency of heterozygotes ($Aa$) under Hardy-Weinberg equilibrium?

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

Question 1

Which of the following best describes the Modern Synthesis in evolutionary biology?

Accepted Answer

It is the integration of Mendelian genetics with Darwinian evolution, explaining how genetic variation leads to evolutionary change.

Question 2

A population of moths shifts from mostly light-colored to mostly dark-colored individuals after pollution darkens tree bark. Which type of natural selection does this scenario illustrate?

Accepted Answer

Directional selection

Question 3

Which equation represents the Hardy-Weinberg equilibrium for allele frequencies in a population?

Accepted Answer

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

Question 4

Which evolutionary mechanism is most likely to increase genetic variation within a population?

Accepted Answer

Mutation

Question 5

A small group of finches migrates to a new island and establishes a population. Over generations, their allele frequencies differ from the original population. This is an example of:

Accepted Answer

Founder effect

Question 6

Which of the following scenarios best illustrates stabilizing selection?

Accepted Answer

Human birth weights are most commonly in the middle range, with very high and very low weights having higher mortality.

Question 7

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

Accepted Answer

Gene flow

Question 8

In a population, the frequency of allele $A$ is $0.7$ and allele $a$ is $0.3$. What is the expected frequency of heterozygotes ($Aa$) under Hardy-Weinberg equilibrium?

Accepted Answer

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

Question 9

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

Accepted Answer

Non-random mating

Question 10

A population of birds has two distinct beak sizes, with few individuals of intermediate size. What type of selection is most likely responsible?

Accepted Answer

Disruptive selection

Question 11

Which evolutionary mechanism is most likely to decrease genetic diversity in a small population due to random changes in allele frequencies?

Accepted Answer

Genetic drift

Question 12

Which of the following best describes balancing selection?

Accepted Answer

It maintains multiple alleles in a population, often due to heterozygote advantage or frequency-dependent selection.

Question 13

A population of deer is isolated by a newly constructed highway, preventing migration. Over time, the two populations develop different allele frequencies. Which evolutionary process is most directly affected?

Accepted Answer

Gene flow

Question 14

Which of the following is an example of sexual selection?

Accepted Answer

Peacocks with larger, more colorful tails attracting more mates.

Question 15

If a mutation occurs in a gene, which of the following is true regarding its evolutionary impact?

Accepted Answer

It introduces new genetic variation, which may be beneficial, neutral, or harmful.

Question 16

Which scenario best illustrates the bottleneck effect?

Accepted Answer

A population of cheetahs is reduced to a few individuals due to habitat loss, resulting in low genetic diversity.

Question 17

Which of the following is a consequence of inbreeding depression?

Accepted Answer

Increased expression of deleterious recessive alleles, leading to reduced fitness.

Question 18

Which process is most likely to result in adaptation to a changing environment?

Accepted Answer

Natural selection

Question 19

A population of wildflowers has red, pink, and white phenotypes. If pollinators prefer the rarest color, which type of selection is occurring?

Accepted Answer

Frequency-dependent selection

Question 20

Which of the following statements about mutation is correct?

Accepted Answer

Mutation is the ultimate source of genetic variation in populations.

Evolutionary Processes: Mechanisms of Evolution in Populations

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