4.2.3 Hardy-Weinberg and reproductive isolation Quiz: Pearson Edexcel Biology, Unit 4

The 20 questions

1. What does the Hardy-Weinberg equation p² + 2pq + q² = 1 calculate?

   • Allele frequencies
   • Mutation rates
   • Expected genotype frequencies
   • Phenotypic ratio

2. In the Hardy-Weinberg equation, what does p represent?

   • Recessive allele frequency
   • Homozygous dominant frequency
   • Heterozygous genotype frequency
   • Dominant allele frequency

3. Which condition disrupts Hardy-Weinberg equilibrium in a population?

   • No natural selection
   • Large population size
   • High mutation rate
   • Random mating

4. What term describes two groups that can no longer interbreed and so no longer share genes?

   • Directional selection
   • Stabilising selection
   • Reproductive isolation
   • Genetic drift

5. How does reproductive isolation lead to speciation between populations?

   • Promotes random mating
   • Prevents gene flow
   • Increases mutation rate
   • Reduces genetic drift

6. Which mechanism is an example of prezygotic reproductive isolation?

   • Hybrid sterility
   • Reduced hybrid fertility
   • Behavioural differences
   • Hybrid inviability

7. If the frequency of the recessive allele q is 0.3, what is the frequency of the dominant allele p?

   • 0.09
   • 0.3
   • 0.7
   • 0.6

8. In a population in Hardy-Weinberg equilibrium, q = 0.2. What is the expected frequency of heterozygotes (2pq)?

   • 0.32
   • 0.16
   • 0.04
   • 0.64

9. A recessive genetic condition affects 1 in 10000 people (q^2 = 0.0001). Approximately what fraction of people are carriers (heterozygotes)?

   • About 1 in 200
   • About 1 in 100
   • About 1 in 50
   • About 1 in 10

10. In a sample of 500 individuals, 45 show the recessive phenotype (aa). What is the frequency q of allele a?

    • 0.45
    • 0.7
    • 0.09
    • 0.3

11. A population of 1000 has 360 AA, 480 Aa and 160 aa individuals. What is the frequency of allele A?

    • 0.6
    • 0.36
    • 0.72
    • 0.5

12. A population is in Hardy-Weinberg equilibrium with p = 0.6 and q = 0.4. How many of 1000 individuals are expected to be heterozygous?

    • 240
    • 360
    • 600
    • 480

13. What process occurs when allele frequencies change over successive generations?

    • Genetic bottleneck
    • Hardy-Weinberg equilibrium
    • Sympatric speciation
    • Evolution

14. In a population of 200 with p = 0.5, what is the expected number of homozygous recessive individuals?

    • 25
    • 50
    • 100
    • 150

15. Hybrids from two diverged populations are sterile, as with mules. Which type of isolating mechanism is this?

    • Postzygotic isolation
    • Prezygotic isolation
    • Geographic isolation only
    • Temporal isolation

16. Why is natural selection slow to eliminate rare recessive alleles?

    • High mutation rate
    • Dominant phenotype expression
    • Gametic incompatibility
    • Masked in heterozygotes

17. Which condition allows two isolated populations to diverge genetically over time?

    • High gene flow
    • Constant environment
    • Random mating
    • No gene flow

18. A population has p = 0.7. Each generation, individuals with p = 0.3 migrate in and make up 10% of the breeding population. What is p after one generation of migration (ignoring other forces)?

    • 0.70
    • 0.66
    • 0.78
    • 0.52

19. A population starts with AA 0.5, Aa 0.0 and aa 0.5, with random mating and no other forces. What are the genotype frequencies in the next generation?

    • AA 0.25, Aa 0.50, aa 0.25
    • AA 0.50, Aa 0.25, aa 0.25
    • AA 0.125, Aa 0.75, aa 0.125
    • AA 0.50, Aa 0.00, aa 0.50

20. In which type of population is genetic drift most significant?

    • Migrating population
    • Large population
    • Small population
    • Equilibrium population

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