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AP Biology Practice Quiz: Hardy-Weinberg Equilibrium

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 9 questions to check your progress.

Question 1 of 9

The Hardy-Weinberg equilibrium model is primarily used to describe which of the following?

All Questions (9)

The Hardy-Weinberg equilibrium model is primarily used to describe which of the following?

A) The rate of speciation in a rapidly changing environment.

B) The allele frequencies within a population that is not evolving.

C) The genetic makeup of an individual organism.

D) The process of genetic mutation over several generations.

Correct Answer: B

Based on the provided content, "The Hardy-Weinberg equilibrium is a model describing allele frequencies in a non-evolving population."

According to the principles of Hardy-Weinberg equilibrium, which of the following is a necessary condition for a population's allele frequencies to remain constant?

A) The population size must be small.

B) Mating must be non-random.

C) Natural selection must be occurring.

D) There must be no migration.

Correct Answer: D

The provided content lists "no migration" as a required condition for a non-evolving population described by the Hardy-Weinberg equilibrium. The other options are the opposite of the required conditions.

Which of the following scenarios would most likely lead to a change in the allele and genotype frequencies of a population?

A) A large, isolated population of fish where individuals mate randomly.

B) A population of plants where a new mutation affecting flower color arises.

C) A population where all individuals have an equal chance of survival and reproduction.

D) A population that has maintained a constant large size for thousands of generations.

Correct Answer: B

The content states that "no mutation" is a condition for Hardy-Weinberg equilibrium. Therefore, the occurrence of a new mutation would cause allele and genotype frequencies to change, disrupting the equilibrium.

A population is considered to be in Hardy-Weinberg equilibrium if all of the following conditions are met EXCEPT:

A) Mating among individuals is random.

B) The population experiences a high rate of mutation.

C) The population is large enough to prevent random fluctuations in allele frequencies.

D) No natural selection is acting on the population.

Correct Answer: B

The provided text explicitly states that "no mutation" is a required condition for Hardy-Weinberg equilibrium. A high rate of mutation would violate this condition and cause allele frequencies to change.

The Hardy-Weinberg model provides a baseline for understanding population genetics because it describes the conditions required for:

A) rapid evolutionary change.

B) the formation of new species.

C) an absence of evolution.

D) calculating mutation rates.

Correct Answer: C

The content states that the Hardy-Weinberg equilibrium is a model for a "non-evolving population." By defining the conditions under which evolution does not occur, it serves as a null hypothesis against which to measure whether evolutionary forces are acting on a real population.

Under which circumstance can the Hardy-Weinberg equations be accurately used to calculate allele frequencies from genotype frequencies?

A) When the population is actively undergoing natural selection.

B) When there is significant gene flow from a neighboring population.

C) When the population is not evolving.

D) When mating is based on desirable traits.

Correct Answer: C

The provided text states, "In a non-evolving population, allele frequencies can be calculated from genotype frequencies using the Hardy-Weinberg equations." This directly links the use of the equations to the condition of a non-evolving population.

In a certain species of bird, females preferentially choose mates with the brightest plumage. This behavior is an example of a violation of which Hardy-Weinberg condition?

A) Large population size

B) No migration

C) No mutation

D) Random mating

Correct Answer: D

The Hardy-Weinberg model requires random mating, meaning that mate choice is not influenced by genotype or phenotype. When females preferentially choose mates based on a specific trait, mating is not random, thus violating this condition.

According to the principles described, a change in a population's allele frequencies is an expected outcome when:

A) the population is large and isolated from other populations.

B) all individuals in the population have an equal chance of survival and reproduction.

C) individuals from an outside population immigrate and interbreed.

D) the population meets all five conditions for Hardy-Weinberg equilibrium.

Correct Answer: C

The text states that allele frequencies change when the conditions for Hardy-Weinberg equilibrium are not met. One of these conditions is "no migration." The immigration and interbreeding of individuals from an outside population represents migration (gene flow), which will cause allele frequencies to change.

A key condition for a population to be in Hardy-Weinberg equilibrium is the absence of natural selection. This implies that for the population to remain non-evolving:

A) all genotypes must have equal survival and reproductive rates.

B) the population must be small to limit genetic diversity.

C) mutations must occur to create beneficial adaptations.

D) individuals must selectively choose mates with the best traits.

Correct Answer: A

The condition of "no natural selection" means that no single genotype has a survival or reproductive advantage over another. Therefore, all genotypes must have equal survival and reproductive rates for the allele frequencies to remain stable.