1. What is the Hardy-Weinberg principle?
A) The principle of evolution in populations
B) The principle of genetic equilibrium in a population
C) The principle of genetic drift in small populations
D) The principle of natural selection
Answer: B) The principle of genetic equilibrium in a population
Explanation: The Hardy-Weinberg principle states that allele frequencies in a population will remain constant in the absence of evolutionary influences.
2. Which of the following is NOT one of the assumptions of Hardy-Weinberg equilibrium?
A) Random mating
B) No mutation
C) Large population size
D) High rate of migration
Answer: D) High rate of migration
Explanation: The Hardy-Weinberg equilibrium assumes no migration (gene flow) into or out of the population.
3. What is the Hardy-Weinberg equation used to calculate?
A) Genotypic frequencies
B) Phenotypic frequencies
C) Allelic frequencies
D) Evolutionary rates
Answer: A) Genotypic frequencies
Explanation: The Hardy-Weinberg equation is used to calculate genotypic frequencies in a population, given the allelic frequencies.
4. Which of the following is true for a population in Hardy-Weinberg equilibrium?
A) Evolution is occurring
B) Allele frequencies remain constant
C) Natural selection is occurring
D) Genetic drift is evident
Answer: B) Allele frequencies remain constant
Explanation: In Hardy-Weinberg equilibrium, allele frequencies remain constant from generation to generation, indicating no evolution.
5. In a population, the frequency of the allele A is 0.6. What is the frequency of the allele a?
A) 0.4
B) 0.6
C) 0.3
D) 0.2
Answer: A) 0.4
Explanation: Allele frequencies must sum to 1, so if the frequency of allele A is 0.6, the frequency of allele a is 1 – 0.6 = 0.4.
6. In the Hardy-Weinberg equation, what do the variables p and q represent?
A) P is the heterozygote frequency, and q is the homozygote frequency
B) P is the allele frequency of one allele, and q is the allele frequency of the other
C) P is the genotypic frequency, and q is the phenotypic frequency
D) P is the mutation rate, and q is the selection coefficient
Answer: B) P is the allele frequency of one allele, and q is the allele frequency of the other
Explanation: In the Hardy-Weinberg equation, p represents the frequency of one allele (e.g., A), and q represents the frequency of the other allele (e.g., a).
7. What is the genotype frequency of a homozygous dominant individual (AA) in a population where p = 0.7 and q = 0.3?
A) 0.49
B) 0.42
C) 0.21
D) 0.09
Answer: A) 0.49
Explanation: The genotype frequency for homozygous dominant (AA) is p², so 0.7² = 0.49.
8. Which of the following would disrupt Hardy-Weinberg equilibrium?
A) No genetic drift
B) No selection pressures
C) A large population size
D) Natural selection
Answer: D) Natural selection
Explanation: Natural selection is one of the evolutionary forces that disrupt Hardy-Weinberg equilibrium by changing allele frequencies.
9. What is the expected genotypic frequency of heterozygotes (Aa) if p = 0.5 and q = 0.5 in a population?
A) 0.25
B) 0.5
C) 0.75
D) 1.0
Answer: B) 0.5
Explanation: The genotypic frequency for heterozygotes (Aa) is 2pq, so 2(0.5)(0.5) = 0.5.
10. What effect would a large population size have on the Hardy-Weinberg equilibrium?
A) It would increase the rate of mutation
B) It would eliminate genetic drift
C) It would make selection pressures stronger
D) It would reduce allele frequencies
Answer: B) It would eliminate genetic drift
Explanation: A large population size reduces the effects of genetic drift, which is the random fluctuation in allele frequencies in small populations.
11. Which of the following factors can change allele frequencies in a population?
A) Random mating
B) Mutation
C) No gene flow
D) No natural selection
Answer: B) Mutation
Explanation: Mutations can introduce new alleles into a population and change allele frequencies over time.
12. If a population of 1,000 individuals has an allele frequency of 0.7 for a gene, how many individuals would be expected to be heterozygotes if Hardy-Weinberg equilibrium is maintained?
A) 210
B) 490
C) 700
D) 300
Answer: B) 490
Explanation: The expected frequency of heterozygotes is 2pq. If p = 0.7 and q = 0.3, then 2pq = 0.42. Therefore, the number of heterozygotes in a population of 1,000 individuals is 0.42 × 1,000 = 490.
13. Which condition does NOT apply to a population in Hardy-Weinberg equilibrium?
A) No migration
B) Random mating
C) No mutations
D) Small population size
Answer: D) Small population size
Explanation: Hardy-Weinberg equilibrium assumes a large population size to prevent genetic drift from affecting allele frequencies.
14. How does gene flow disrupt Hardy-Weinberg equilibrium?
A) By introducing new mutations
B) By changing allele frequencies through migration
C) By increasing the population size
D) By maintaining the allele frequencies
Answer: B) By changing allele frequencies through migration
Explanation: Gene flow, or migration of individuals between populations, introduces new alleles and can change allele frequencies.
15. What does the Hardy-Weinberg equation assume about mutations?
A) Mutations are constantly occurring
B) Mutations occur only in small populations
C) Mutations have no effect on allele frequencies
D) No mutations occur
Answer: D) No mutations occur
Explanation: The Hardy-Weinberg equilibrium assumes that there are no mutations, meaning that no new alleles are introduced into the gene pool.
16. What does the term “genetic drift” refer to in population genetics?
A) The process of evolution due to environmental pressures
B) The random change in allele frequencies due to chance events
C) The selective survival of certain phenotypes
D) The constant introduction of new genetic material
Answer: B) The random change in allele frequencies due to chance events
Explanation: Genetic drift refers to random changes in allele frequencies due to chance events, especially in small populations.
17. Which of the following is an example of natural selection disrupting Hardy-Weinberg equilibrium?
A) A population of birds with different beak sizes, where larger beaks are advantageous
B) A population with no genetic mutations
C) A large population with random mating
D) A population experiencing no gene flow
Answer: A) A population of birds with different beak sizes, where larger beaks are advantageous
Explanation: Natural selection favors larger beaks in this case, changing allele frequencies and disrupting Hardy-Weinberg equilibrium.
18. What would happen to allele frequencies if a population were isolated and subjected to genetic drift?
A) Allele frequencies would remain constant
B) Allele frequencies would fluctuate randomly
C) Allele frequencies would stabilize
D) Allele frequencies would be driven towards fixation of one allele
Answer: B) Allele frequencies would fluctuate randomly
Explanation: In small populations, genetic drift causes allele frequencies to fluctuate randomly, often leading to the fixation or loss of alleles.
19. What does the Hardy-Weinberg equilibrium model not account for?
A) Evolution through natural selection
B) Changes in allele frequencies over generations
C) Random mating in large populations
D) The non-existence of mutations
Answer: A) Evolution through natural selection
Explanation: The Hardy-Weinberg equilibrium model assumes no evolution occurs, meaning natural selection, mutation, or migration is not influencing allele frequencies.
20. In a population of 1,000 individuals, there are 300 individuals with the genotype AA, 500 with Aa, and 200 with aa. What is the allele frequency of A?
A) 0.6
B) 0.7
C) 0.5
D) 0.4
Answer: A) 0.6
Explanation: The allele frequency of A is calculated by adding the number of A alleles in each genotype (2 × AA + 1 × Aa). Total alleles = 2 × 300 + 1 × 500 + 2 × 200 = 1300. The frequency of A is 1300/2000 = 0.6.
21. Which of the following best describes a population in Hardy-Weinberg equilibrium?
A) The population is evolving
B) Allele frequencies are changing
C) The population is in genetic equilibrium
D) Natural selection is acting
Answer: C) The population is in genetic equilibrium
Explanation: A population in Hardy-Weinberg equilibrium has no evolutionary forces acting upon it, and allele frequencies remain constant.
22. Which process can prevent Hardy-Weinberg equilibrium by favoring one allele over others?
A) Random mating
B) Genetic drift
C) Natural selection
D) Gene flow
Answer: C) Natural selection
Explanation: Natural selection can cause certain alleles to become more frequent while others decrease, disrupting Hardy-Weinberg equilibrium.
23. Which scenario would violate the Hardy-Weinberg assumption of no mutation?
A) A gene mutation introduces a new allele into the population
B) There is random mating in the population
C) The population is large
D) No natural selection is occurring
Answer: A) A gene mutation introduces a new allele into the population
Explanation: Hardy-Weinberg assumes no mutations occur, so the introduction of a new allele by mutation violates this assumption.
24. If the frequency of an allele is 0.4, what is the frequency of the homozygous recessive genotype in Hardy-Weinberg equilibrium?
A) 0.16
B) 0.64
C) 0.4
D) 0.36
Answer: A) 0.16
Explanation: The frequency of the homozygous recessive genotype is q². If q = 0.4, then q² = 0.16.
25. Which of the following is most likely to disrupt Hardy-Weinberg equilibrium?
A) Large population size
B) Random mating
C) Mutation introducing a new allele
D) No gene flow
Answer: C) Mutation introducing a new allele
Explanation: Mutation can introduce new alleles into a population, changing allele frequencies and disrupting Hardy-Weinberg equilibrium.
26. How can migration affect Hardy-Weinberg equilibrium?
A) By introducing new mutations
B) By altering allele frequencies through gene flow
C) By reducing the population size
D) By stabilizing allele frequencies
Answer: B) By altering allele frequencies through gene flow
Explanation: Migration allows new alleles to enter or exit a population, changing allele frequencies and disrupting Hardy-Weinberg equilibrium.
27. In a population, the allele frequency for a dominant allele is 0.7. What is the expected frequency of the recessive genotype (aa) according to Hardy-Weinberg?
A) 0.49
B) 0.21
C) 0.3
D) 0.09
Answer: D) 0.09
Explanation: The frequency of the recessive genotype (aa) is q². If p = 0.7, then q = 1 – 0.7 = 0.3, and q² = 0.09.
28. What factor most strongly contributes to genetic variation in populations?
A) Random mating
B) Natural selection
C) Mutations
D) Genetic drift
Answer: C) Mutations
Explanation: Mutations are the ultimate source of genetic variation, introducing new alleles into a population.
29. What happens if Hardy-Weinberg equilibrium is maintained over multiple generations?
A) The population evolves
B) Allele frequencies remain constant
C) New mutations occur constantly
D) Genetic drift increases
Answer: B) Allele frequencies remain constant
Explanation: If Hardy-Weinberg equilibrium is maintained, allele frequencies do not change from one generation to the next.
30. Which of the following is an example of a population not in Hardy-Weinberg equilibrium?
A) A population of birds with no natural predators
B) A population of beetles where the green phenotype is advantageous
C) A population of rabbits with random mating
D) A large population of humans in isolation
Answer: B) A population of beetles where the green phenotype is advantageous
Explanation: Natural selection favoring a particular phenotype, like the green beetles, violates Hardy-Weinberg equilibrium.
