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Genetics

Population Genetics Practice Questions

39 free Population Genetics practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.

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Question 1 of 39 Medium

Population genetics primarily studies:

  1. A Inheritance patterns within individual family pedigrees
  2. B Changes in allele frequencies within populations
  3. C Structure of chromosomes
  4. D Development of embryos

Correct answer: Changes in allele frequencies within populations

Population genetics focuses on how allele frequencies change over time within populations. These changes are driven by evolutionary forces such as selection, drift, mutation, and gene flow.

Question 2 of 39 Medium

Allele frequency refers to the:

  1. A Proportion of heterozygous individuals in a population
  2. B Number of alleles per gene
  3. C Relative abundance of an allele in a population
  4. D Rate of mutation of an allele

Correct answer: Relative abundance of an allele in a population

Allele frequency measures how common a particular allele is relative to other alleles of the same gene. It is expressed as a proportion of all alleles at that locus.

Question 3 of 39 Medium

The Hardy–Weinberg principle provides a model for populations that are:

  1. A Under strong natural selection
  2. B Very small in size
  3. C Not evolving
  4. D Experiencing high mutation rates

Correct answer: Not evolving

Hardy–Weinberg equilibrium describes populations where allele frequencies remain constant. This occurs when no evolutionary forces act on the population.

Question 4 of 39 Medium

Which condition is required for a population to remain in Hardy–Weinberg equilibrium?

  1. A Small population size
  2. B Non-random mating
  3. C No gene flow
  4. D High mutation rate

Correct answer: No gene flow

For Hardy–Weinberg equilibrium, populations must be closed to migration. Gene flow introduces or removes alleles and disrupts equilibrium.

Question 5 of 39 Medium

Gene flow is best described as:

  1. A Random change in allele frequencies over generations
  2. B Exchange of genes between populations
  3. C Creation of new alleles
  4. D Elimination of harmful alleles

Correct answer: Exchange of genes between populations

Gene flow involves movement of individuals or gametes between populations. This movement transfers alleles and alters allele frequencies.

Question 6 of 39 Medium

Which evolutionary force tends to reduce genetic differences between populations?

  1. A Genetic drift
  2. B Natural selection
  3. C Gene flow
  4. D Mutation

Correct answer: Gene flow

Gene flow introduces alleles into populations and makes them genetically more similar. It counteracts divergence caused by drift or selection.

Question 7 of 39 Medium

If the frequency of allele A is 0.7 in a population, the frequency of allele a (assuming two alleles) is:

  1. A 0.3
  2. B 0.49
  3. C 0.21
  4. D 0.7

Correct answer: 0.3

In a two-allele system, allele frequencies sum to 1. Therefore, the frequency of allele a is 1 − 0.7 = 0.3.

Question 8 of 39 Medium

Which factor directly introduces new alleles into a population?

  1. A Natural selection
  2. B Genetic drift
  3. C Mutation
  4. D Non-random mating

Correct answer: Mutation

Mutation creates new alleles by altering DNA sequences. Other forces only change the frequencies of existing alleles.

Question 9 of 39 Medium

In a Hardy–Weinberg population, the frequency of heterozygotes is represented by:

  1. A p²
  2. B q²
  3. C 2pq
  4. D p + q

Correct answer: 2pq

Under Hardy–Weinberg equilibrium, heterozygotes occur with frequency 2pq. Here, p and q represent allele frequencies.

Question 10 of 39 Medium

Migration of individuals into a population is known as:

  1. A Emigration out of the population
  2. B Immigration
  3. C Random mutation of alleles
  4. D Directional selection

Correct answer: Immigration

Immigration adds new individuals and alleles to a population. This can change allele frequencies through gene flow.

Question 11 of 39 Medium

Genetic drift has the strongest effect in populations that are:

  1. A Large and stable
  2. B Small and isolated
  3. C Experiencing high gene flow
  4. D Under strong selection

Correct answer: Small and isolated

Genetic drift causes random fluctuations in allele frequencies. Its effects are strongest in small populations.

Question 12 of 39 Medium

Which of the following violates the assumptions of Hardy–Weinberg equilibrium?

  1. A Completely random mating among individuals
  2. B Large effective population size
  3. C No mutation over time
  4. D Directional selection

Correct answer: Directional selection

Directional selection favors one allele over others. This changes allele frequencies and violates equilibrium conditions.

Question 13 of 39 Medium

Gene flow can introduce maladaptive alleles into a population, a process known as:

  1. A Accumulated genetic load
  2. B Outbreeding depression
  3. C Founder effect after colonization
  4. D Adaptive radiation of species

Correct answer: Outbreeding depression

Outbreeding depression occurs when gene flow introduces alleles poorly suited to local conditions. This can reduce population fitness.

Question 14 of 39 Medium

The founder effect is a special case of:

  1. A Gene flow
  2. B Mutation
  3. C Genetic drift
  4. D Natural selection

Correct answer: Genetic drift

The founder effect occurs when a small number of individuals establish a new population. Allele frequencies can differ greatly due to genetic drift.

Question 15 of 39 Medium

Which equation represents Hardy–Weinberg equilibrium?

  1. A p² + q² = 1 for the two alleles
  2. B p + q = 1
  3. C p² + 2pq + q² = 1
  4. D p − q = 1

Correct answer: p² + 2pq + q² = 1

The Hardy–Weinberg equation p² + 2pq + q² = 1 describes genotype frequencies. It assumes random mating and no evolutionary forces.

Question 16 of 39 Medium

Which type of gene flow occurs when pollen is carried between plant populations?

  1. A Gamete migration
  2. B Somatic mutation in body cells
  3. C Random genetic drift over time
  4. D Selection against pollen

Correct answer: Gamete migration

In plants, gene flow often occurs via pollen dispersal. This represents migration of gametes between populations.

Question 17 of 39 Medium

An increase in homozygosity within a population is most likely due to:

  1. A Random mating
  2. B Gene flow
  3. C Inbreeding
  4. D High mutation rates

Correct answer: Inbreeding

Inbreeding increases the likelihood that related individuals mate. This raises homozygosity without changing allele frequencies.

Question 18 of 39 Medium

Which evolutionary force changes allele frequencies in a non-random direction based on fitness?

  1. A Random genetic drift over generations
  2. B Spontaneous mutation of DNA
  3. C Gene flow between populations
  4. D Natural selection

Correct answer: Natural selection

Natural selection favors alleles that increase fitness. This leads to predictable, non-random changes in allele frequencies.

Question 19 of 39 Medium

If a population experiences high gene flow, local adaptation is likely to be:

  1. A Enhanced
  2. B Unchanged
  3. C Reduced
  4. D Fixed permanently

Correct answer: Reduced

High gene flow introduces alleles from other populations. This can dilute locally adapted gene combinations.

Question 20 of 39 Medium

Population subdivision most directly promotes:

  1. A Uniform allele frequencies
  2. B Genetic divergence
  3. C Hardy–Weinberg equilibrium
  4. D Increased gene flow

Correct answer: Genetic divergence

Subdivision restricts gene flow between groups. Over time, this leads to genetic divergence among populations.

Question 21 of 39 Medium

Allele frequency in a population refers to:

  1. A Number of individuals with a trait
  2. B Proportion of a specific allele among all alleles of a gene
  3. C The total count of every distinct gene locus found within a population's gene pool
  4. D Number of mutations per generation

Correct answer: Proportion of a specific allele among all alleles of a gene

Allele frequency is the relative proportion of a particular allele among all alleles of that gene in a population. It is a key measure in population genetics.

Question 22 of 39 Medium

If the frequency of allele A (p) is 0.6, what is the frequency of allele a (q) in a two-allele system?

  1. A 0.2
  2. B 0.4
  3. C 0.6
  4. D 1.0

Correct answer: 0.4

In a two-allele system, p + q = 1. If p = 0.6, then q = 1 - 0.6 = 0.4.

Question 23 of 39 Medium

Which process directly moves alleles between populations?

  1. A Mutation
  2. B Gene flow
  3. C Genetic drift
  4. D Natural selection

Correct answer: Gene flow

Gene flow involves the transfer of alleles between populations through migration or movement of gametes. It increases genetic connectivity between populations.

Question 24 of 39 Medium

Which factor tends to homogenize allele frequencies between populations?

  1. A Genetic drift
  2. B Mutation
  3. C Gene flow
  4. D Selection

Correct answer: Gene flow

Gene flow reduces differences between populations by spreading alleles. This leads to more similar allele frequencies across populations.

Question 25 of 39 Medium

In Hardy–Weinberg equilibrium, what does p^2 represent?

  1. A Frequency of heterozygotes
  2. B Frequency of homozygous dominant genotype
  3. C Frequency of homozygous recessive genotype
  4. D Mutation rate

Correct answer: Frequency of homozygous dominant genotype

In Hardy–Weinberg equilibrium, p^2 represents the frequency of the homozygous dominant genotype. It is derived from allele frequency p.

Question 26 of 39 Medium

Which condition is NOT required for Hardy–Weinberg equilibrium?

  1. A Random mating
  2. B Large population size
  3. C Natural selection
  4. D No mutation

Correct answer: Natural selection

Hardy–Weinberg equilibrium assumes no natural selection. Selection would change allele frequencies and violate equilibrium conditions.

Question 27 of 39 Medium

What is the expected frequency of heterozygotes if p = 0.5 and q = 0.5?

  1. A 0.25
  2. B 0.75
  3. C 1.0
  4. D 0.5

Correct answer: 0.5

The frequency of heterozygotes is given by 2pq. If p = q = 0.5, then 2pq = 2 × 0.5 × 0.5 = 0.5.

Question 28 of 39 Medium

Which evolutionary force introduces entirely new alleles into a population?

  1. A Gene flow
  2. B Genetic drift
  3. C Migration
  4. D Mutations

Correct answer: Mutations

Mutation creates new alleles by altering DNA sequences. It is the ultimate source of genetic variation.

Question 29 of 39 Medium

What is gene flow also commonly referred to as?

  1. A Selection
  2. B Recombination
  3. C Mutation
  4. D Migration

Correct answer: Migration

Gene flow is often described as migration because it involves the movement of individuals or gametes between populations. This results in allele transfer.

Question 30 of 39 Medium

Which situation would most likely increase genetic variation within a population?

  1. A Isolation
  2. B Inbreeding
  3. C Selection against variation
  4. D Gene flow

Correct answer: Gene flow

Gene flow introduces new alleles into a population. This increases genetic diversity and variation.

Question 31 of 39 Medium

Which term describes the sum of all alleles in a population?

  1. A Gene pool
  2. B Genome
  3. C Karyotype
  4. D Phenotype

Correct answer: Gene pool

The gene pool includes all alleles present in a population. It represents the total genetic diversity available.

Question 32 of 39 Medium

Which Hardy–Weinberg assumption is violated if individuals prefer mates with similar traits?

  1. A Random mating
  2. B No mutation
  3. C Large population size
  4. D No gene flow

Correct answer: Random mating

Preference for similar mates is non-random mating. This violates one of the key assumptions of Hardy–Weinberg equilibrium.

Question 33 of 39 Medium

Which genotype frequency is represented by q^2 in Hardy–Weinberg equilibrium?

  1. A Homozygous dominant genotype
  2. B Heterozygous
  3. C Homozygous recessive
  4. D Mutant genotype

Correct answer: Homozygous recessive

q^2 represents the frequency of homozygous recessive individuals. It is derived from allele frequency q.

Question 34 of 39 Medium

What effect does isolation have on allele frequencies?

  1. A Makes populations identical
  2. B Prevents any changes in allele frequencies
  3. C Allows divergence between populations
  4. D Increases gene flow

Correct answer: Allows divergence between populations

Isolation prevents gene flow, allowing populations to evolve independently. This can lead to divergence in allele frequencies.

Question 35 of 39 Medium

Which process can counteract the effects of genetic drift?

  1. A Gene flow
  2. B Mutation
  3. C Selection
  4. D Inbreeding

Correct answer: Gene flow

Gene flow introduces alleles from other populations, reducing random changes caused by genetic drift. It stabilizes allele frequencies.

Question 36 of 39 Medium

What happens to allele frequencies under Hardy–Weinberg equilibrium?

  1. A They increase continuously
  2. B They decrease continuously
  3. C They remain constant
  4. D They fluctuate

Correct answer: They remain constant

Under Hardy–Weinberg equilibrium, allele frequencies remain constant across generations. This occurs when no evolutionary forces act on the population.

Question 37 of 39 Medium

Which factor is most likely to cause a sudden change in allele frequency in a small population?

  1. A Gene flow
  2. B Spontaneous mutation
  3. C Selection
  4. D Genetic drift

Correct answer: Genetic drift

Genetic drift has a stronger effect in small populations. It can cause rapid and random changes in allele frequencies.

Question 38 of 39 Medium

Which type of mating increases homozygosity in a population?

  1. A Random mating
  2. B Outbreeding
  3. C Cross-pollination
  4. D Close inbreeding

Correct answer: Close inbreeding

Inbreeding increases the likelihood of individuals inheriting identical alleles from both parents. This leads to increased homozygosity.

Question 39 of 39 Medium

Which statement best describes allele frequency change due to gene flow?

  1. A It introduces outside alleles
  2. B It is always random
  3. C It removes alleles permanently
  4. D It only affects small populations

Correct answer: It introduces outside alleles

Gene flow involves the movement of alleles between populations. It can introduce new alleles and alter allele frequencies.

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