Question 1

Which of the following statements best describes the Hardy–Weinberg principle?

Accepted Answer

It serves as a mathematical null hypothesis for the study of evolutionary processes, assuming allele frequencies remain constant under specific conditions.

Question 2

A population of butterflies has two alleles for the Pgi gene: A and C. If the frequency of allele A is $p = 0.6$ and the frequency of allele C is $q = 0.4$, what is the expected frequency of AC heterozygotes under Hardy–Weinberg equilibrium?

Accepted Answer

$2pq = 0.48$

Question 3

Which of the following is NOT an assumption of the Hardy–Weinberg principle?

Accepted Answer

Small population size

Question 4

In a population of flowering plants, self-fertilization occurs. Over several generations, what is the most likely effect on genotype frequencies?

Accepted Answer

Increase in homozygotes and decrease in heterozygotes

Question 5

Which evolutionary process is described as random changes in allele frequencies, most important in small populations, and often leads to loss or fixation of alleles?

Accepted Answer

Genetic drift

Question 6

A population bottleneck can lead to which of the following outcomes?

Accepted Answer

Random loss of alleles and reduced genetic variation

Question 7

Which mode of natural selection favors extreme phenotypes at both ends of the range and increases variation in a trait?

Accepted Answer

Disruptive selection

Question 8

In the case study of steelhead trout, gene flow from captive-bred to wild populations resulted in:

Accepted Answer

Decreased fitness in wild populations

Question 9

Which of the following best explains why mutation is considered the ultimate source of genetic variation?

Accepted Answer

Mutation creates entirely new alleles, not just new combinations.

Question 10

A population of finches experienced a drought, and the average beak depth increased. Which mode of selection is most likely responsible for this change?

Accepted Answer

Directional selection

Question 11

Which process equalizes allele frequencies between source and recipient populations, often reducing genetic differences?

Accepted Answer

Gene flow

Question 12

If a population is not in Hardy–Weinberg equilibrium for a particular gene, what can you conclude?

Accepted Answer

Evolution is occurring at that gene.

Question 13

Which of the following is true about inbreeding depression?

Accepted Answer

It is a decline in average fitness due to increased homozygosity and decreased heterozygosity.

Question 14

Which equation represents the Hardy–Weinberg equilibrium for a gene with two alleles?

Accepted Answer

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

Question 15

Which evolutionary process is random with respect to fitness and can either increase or decrease fitness depending on the situation?

Accepted Answer

Gene flow

Question 16

A founder event occurs when a small group of individuals establishes a new population. What is the most likely genetic consequence?

Accepted Answer

Allele frequencies in the new population differ from the source population due to sampling error.

Question 17

Which mode of selection maintains genetic variation in a population by favoring rare alleles?

Accepted Answer

Balancing selection

Question 18

Which of the following is a real-world example of a genetic bottleneck?

Accepted Answer

A human population reduced to 20 individuals after natural disasters, resulting in high frequency of a rare allele.

Question 19

Which statement about mutation is correct?

Accepted Answer

Mutation is random with respect to fitness and most often produces deleterious alleles.

Chapter 23: Evolutionary Processes – Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards