Lesson 5.6.1

5.6.1 Evolution by gene mutation and natural selection Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.6.1, Evolution by gene mutation and natural selection: 20 multiple choice questions for the Pearson Edexcel Biology A (Salters-Nuffield) (9BI0), Unit 5: On the Wild Side, written with Revision Ninja.

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The 20 questions

  1. What is the source of new alleles in a population?

    • Genetic drift in small populations
    • Gene flow between populations
    • Natural selection
    • Gene mutation

  2. What does natural selection act on?

    • The number of predators in the habitat only
    • Random changes in environmental temperature only
    • Heritable variation affecting survival and reproduction
    • Acquired characteristics that are not inherited

  3. What is evolution, in terms of allele frequencies?

    • A change in the temperature of a habitat
    • A change in the number of species in a habitat each year
    • A change in the allele frequency of a population over generations
    • A change in the colour of an individual during its life

  4. Which process can lead to a change in allele frequency through differential survival?

    • Osmosis
    • Photosynthesis
    • Natural selection
    • Respiration

  5. In a population, a mutation gives a beak allele that improves seed-cracking. Over generations, what is the most likely outcome?

    • The allele has no effect on allele frequency
    • The allele frequency rises as its carriers breed more
    • The allele disappears because it is beneficial
    • The allele becomes dominant in the population instantly

  6. Why is gene mutation described as random?

    • Mutations arise without regard to whether they benefit the organism
    • Mutations are caused by natural selection choosing them
    • Mutations always occur in the same gene in every organism
    • Mutations only arise in plants

  7. Which is the correct sequence of steps in evolution by natural selection?

    • Species are created in a single step with no change in allele frequency
    • Individuals change their genes during their lifetime to suit the environment
    • Mutation gives variation; selection changes allele frequency
    • Allele frequency changes first, then mutations arise to match it

  8. A population is exposed to an antibiotic. Resistant bacteria survive and reproduce. What process has occurred?

    • Osmosis across the bacterial cell membrane
    • Photosynthesis occurring in the bacterial cells
    • Acquired immunity developed by each bacterium
    • Natural selection favouring a resistance allele

  9. Why does a rare recessive allele persist in a population for several generations?

    • It hides in heterozygotes, escaping selection
    • It is immediately expressed in all individuals
    • Recessive alleles cannot be passed on
    • It is always lost after a single generation

  10. Which statement about isolation and gene flow is correct?

    • Isolation increases gene flow between populations
    • Isolation reduces gene flow and lets populations diverge
    • Isolation has no effect on allele frequencies
    • Gene flow is only possible between identical populations

  11. What is allopatric speciation?

    • Speciation that occurs after populations are geographically separated
    • Speciation that occurs within a single population with no separation
    • Speciation caused by a change in photosynthesis rate
    • Speciation caused by respiration in different habitats

  12. What is sympatric speciation?

    • Speciation that occurs in the same area without geographic separation
    • Speciation caused by movement of organisms to a new continent
    • Speciation that occurs only after geographic separation
    • Speciation caused by extinction of all but one population

  13. Which factor can lead to sympatric speciation?

    • A geographic barrier such as a mountain range
    • A behavioural difference that stops interbreeding
    • Identical allele frequencies in every subgroup
    • A total absence of mutation in the population

  14. Why does reduced gene flow between populations lead to speciation over time?

    • Reduced gene flow makes all populations identical
    • Reduced gene flow removes all variation from the populations
    • Reduced gene flow stops mutations from occurring
    • Alleles diverge, possibly preventing interbreeding

  15. A student says natural selection creates new alleles. What is the best evaluation?

    • Incorrect, because alleles are never created at all
    • Correct, because selection and mutation are identical processes
    • Incorrect: selection acts on existing variation
    • Correct, because selection creates new alleles directly

  16. A snail population is split by a river. After many generations, the two groups differ in shell shape. Which process is most consistent with this?

    • Sympatric speciation within a single shared area
    • Allopatric speciation after geographic separation
    • Random change of shell colour during life
    • Acquired changes caused by feeding on different plants

  17. Why must a change in allele frequency be heritable to contribute to evolution?

    • Heritable changes are never passed to offspring
    • Non-heritable changes always increase allele frequency
    • Evolution does not depend on any inheritance
    • Only inherited changes reach the next generation

  18. What is genetic drift?

    • Directed changes in allele frequency caused by beneficial mutations
    • Random changes in allele frequency, most pronounced in small populations
    • Selection that always favours the dominant allele
    • Movement of alleles between populations only

  19. Why does a population with more genetic variation usually respond better to a changing environment?

    • Variation stops natural selection from acting on the population
    • Variation makes all individuals identical, which helps them survive
    • More alleles give more phenotypes to select from
    • Variation prevents any change in allele frequency

  20. Which example is a geographic barrier that could drive allopatric speciation?

    • Two fish groups breeding at different times of year in one lake
    • Two groups of birds feeding on different seeds in the same wood
    • A river separating two groups of the same snail species
    • Two plant groups flowering at different times in one meadow

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