Lesson 3.7.3.1

3.7.3.1 Variation, selection and the evolution of species Quiz: AQA Biology, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.7.3.1, Variation, selection and the evolution of species: 20 multiple choice questions for the AQA Biology (7402), Unit 7: Genetics, populations, evolution and ecosystems, written with Revision Ninja.

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The 20 questions

  1. What is the primary source of genetic variation in a population?

    • Random fertilisation
    • Natural selection
    • Mutation
    • Meiosis

  2. Which meiotic process creates further genetic variation during sexual reproduction?

    • Independent assortment
    • Cytokinesis
    • Binary fission
    • DNA replication

  3. What is the primary driver of natural selection in a population?

    • Random genetic drift
    • Identical reproduction
    • Differential survival
    • Environmental stasis

  4. Which phenotypes are favoured by stabilising selection in a population?

    • Mutated phenotypes
    • Intermediate phenotypes
    • Extreme phenotypes
    • Recessive phenotypes

  5. In which direction does the population mean shift during directional selection?

    • Towards one extreme
    • Away from extremes
    • Towards both extremes
    • Towards the centre

  6. What does disruptive selection predominantly select against in a population?

    • Extreme phenotypes
    • Novel mutations
    • Rare alleles
    • Intermediate phenotypes

  7. What biological factor strictly defines evolution over generations?

    • Population decline
    • Species extinction
    • Allele frequency change
    • Phenotype constancy

  8. In a bird population most individuals have a medium beak size, while very small and very large beaks are disadvantageous. Which type of selection is operating?

    • Stabilising selection
    • Sexual selection
    • Disruptive selection
    • Directional selection

  9. Antibiotic resistance in bacteria is an example of which evolutionary process?

    • Directional selection
    • Artificial selection
    • Stabilising selection
    • Disruptive selection

  10. Predation and disease directly cause what outcome in a population?

    • Genetic equilibrium
    • Uniform survival
    • Reduced mutation
    • Differential reproduction

  11. Which process introduces brand new alleles into a gene pool?

    • Mitosis
    • Fertilisation
    • Mutation
    • Respiration

  12. Industrial melanism in peppered moths is a classic example of what?

    • Disruptive selection
    • Stabilising selection
    • Directional selection
    • Allopatric speciation

  13. What is the typical effect of stabilising selection on genetic variation?

    • Doubled variation
    • Decreased variation
    • Increased variation
    • No change

  14. Disruptive selection can eventually lead to the formation of how many distinct phenotypes?

    • Three
    • Two
    • One
    • Four

  15. Why is a newly arisen mutant allele initially very rare?

    • Dominant inheritance
    • Rapid degradation
    • Single origin
    • Always lethal

  16. What accumulates over successive generations under directional selection?

    • Constant phenotypes
    • Recessive alleles
    • Lethal mutations
    • Favoured alleles

  17. Survival to reproduction is 0.6 for phenotype X and 0.9 for phenotype Y. What is the relative fitness of X compared with Y?

    • 0.54
    • 1.50
    • 0.30
    • 0.67

  18. What type of variation is strictly required for natural selection to act?

    • Environmental variation
    • Heritable variation
    • Temporary variation
    • Acquired variation

  19. Accumulated genetic differences over long evolutionary periods lead directly to what?

    • Cloning
    • Mitosis
    • Speciation
    • Homeostasis

  20. Put these events in the most likely order during selection: 1 a phenotype is favoured, 2 favoured alleles rise in frequency, 3 individuals with the phenotype produce more offspring, 4 the gene pool changes. Which sequence is correct?

    • 1, 3, 2, 4
    • 1, 2, 3, 4
    • 2, 1, 3, 4
    • 3, 1, 2, 4

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