Lesson 5.6.3

5.6.3 Isolation, gene flow and speciation Quiz: Pearson Edexcel Biology, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.6.3, Isolation, gene flow and speciation: 20 multiple choice questions for the Pearson Edexcel Biology (9BI0), Unit 5: On the Wild Side, written with Revision Ninja.

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The 20 questions

  1. What name is given to the movement of alleles between different populations?

    • Natural selection
    • Gene flow
    • Gene mutation
    • Genetic drift

  2. What type of isolation causes allopatric speciation to occur?

    • Geographical isolation
    • Ecological isolation
    • Temporal isolation
    • Behavioural isolation

  3. Where does sympatric speciation occur relative to the original population?

    • In isolated islands
    • In same area
    • Across physical barriers
    • In separate continents

  4. Which of these is an example of prezygotic reproductive isolation?

    • Hybrid sterility
    • Hybrid inviability
    • Hybrid breakdown
    • Temporal isolation

  5. What type of isolation occurs when hybrid embryos fail to develop after fertilisation?

    • Prezygotic isolation
    • Geographical isolation
    • Temporal isolation
    • Postzygotic isolation

  6. What has evolved when two separated populations can no longer interbreed successfully?

    • Sympatric speciation
    • Reproductive isolation
    • Gene flow
    • Genetic equilibrium

  7. Evolution is best defined as a change in which quantity over time?

    • Chromosome number
    • Mutation rate
    • Gene number
    • Allele frequency

  8. Which process causes random changes in allele frequencies, mostly affecting small populations?

    • Genetic drift
    • Directional selection
    • Gene flow
    • Artificial selection

  9. What happens to allele frequencies in two populations separated by a physical barrier?

    • They become equal
    • They diverge
    • They stabilise completely
    • They remain identical

  10. Population A has a frequency of 0.60 for allele A and population B has a frequency of 0.40. What is the difference in frequency of allele A between the two populations?

    • 1.00
    • 0.60
    • 0.20
    • 0.40

  11. In a population, 160 of 400 individuals show a recessive phenotype. What is frequency q?

    • 0.16
    • 0.40
    • 0.37
    • 0.63

  12. Allele B has a frequency of 0.30 in a population at the start and 0.45 after 10 generations. What is the average change in frequency per generation?

    • 0.045 per generation
    • 0.15 per generation
    • 0.015 per generation
    • 0.0015 per generation

  13. In Hardy-Weinberg equilibrium with allele frequency p = 0.7, what is the heterozygote frequency?

    • 0.42
    • 0.49
    • 0.09
    • 0.21

  14. Two frog populations live together but breed at different times of year. What isolation is this?

    • Ecological isolation
    • Temporal isolation
    • Behavioural isolation
    • Geographical isolation

  15. Which genetic mechanism can rapidly cause sympatric speciation in plants?

    • Natural selection
    • Gene flow
    • Polyploidy
    • Genetic drift

  16. What must evolve during geographical isolation for speciation to permanently occur?

    • Reproductive isolation
    • Polyploidy
    • Continuous gene flow
    • Identical mutations

  17. Two separated populations reunite and interbreed successfully. What failed to evolve between them?

    • Phenotypic variation
    • Reproductive isolation
    • Geographical barriers
    • Allele mutations

  18. Reduced gene flow between two populations leads to which outcome?

    • Equal allele frequencies
    • Increased gene flow
    • Faster allele divergence
    • Lower mutation rates

  19. Which factor reduces the effect of genetic drift in a population?

    • High mutation rate
    • Low gene flow
    • Small population size
    • Large population size

  20. Why do mutations provide the raw material for speciation?

    • Fixing allele frequencies
    • Creating new alleles
    • Causing geographic isolation
    • Preventing gene flow

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