Lesson T4.2.3

T4.2.3 Natural selection and competition Quiz: KS3 Biology, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T4.2.3, Natural selection and competition: 20 multiple choice questions for the KS3 Biology (National Curriculum), Unit 4: Genetics and evolution, written with Revision Ninja.

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The 20 questions

  1. What is natural selection?

    • The deliberate breeding of farm animals by humans to select useful traits
    • A change in the environment caused by a single organism moving into a habitat
    • The process where individuals with advantageous variations survive and reproduce more
    • The process of cell division in a zygote that produces identical copies of cells

  2. Why do some organisms compete more successfully than others?

    • They have variations that help them get food, mates or space
    • They are always the oldest organisms in the population being studied
    • They have no competitors because they live in a very isolated place
    • They always have a larger number of cells than other organisms

  3. What is the main resource that organisms compete for?

    • Chromosomes only
    • Oxygen gas only
    • Food, water, light, mates or space
    • Minerals stored in the nucleus

  4. Which result of natural selection leads to evolution?

    • Organisms stop reproducing when they are young, before they can mate
    • Individuals become larger during their lifetime through steady growth
    • All variation in the population disappears at once in a single event
    • Advantageous genes become more common in the population over generations

  5. Why might a bird with a longer beak be more successful in some habitats?

    • It is always taller than other birds in the flock, so it sees food first
    • Its beak makes it immune to disease, so it lives much longer than others
    • It can photosynthesise through its beak, so it needs less food overall
    • It can reach a food source that others cannot, so it survives and reproduces

  6. A moth population has light and dark forms. Dark moths are camouflaged on dirty trees. What is most likely?

    • Light moths are always more common on the dirty trees in the wood
    • Dark moths survive more often and their numbers increase
    • Dark moths stop reproducing once the trees become dirty and grey
    • The environment makes all moths dark in every generation regardless

  7. What happens to individuals that are less well adapted to competing?

    • They are less likely to survive and reproduce
    • They become the new species
    • They stop being affected by competition
    • They always survive best

  8. Which statement describes natural selection correctly?

    • Individuals with useful variations are more likely to pass on their genes
    • Individuals choose which genes they will pass on
    • The environment causes all organisms to change deliberately
    • Natural selection happens only in animals

  9. Why does natural selection need variation within a population?

    • Without variation, no individuals would have advantageous features to be selected
    • Variation makes the environment change so that all species must adapt together
    • Variation stops organisms from competing for food, water, light and mates
    • Variation is needed to make cells divide during growth, repair and reproduction

  10. Which factor can make some individuals in a species less well adapted to compete?

    • Having the same genes as the rest of the population
    • Being born in summer
    • Eating the same food as other individuals
    • A change in the environment, such as a new predator

  11. What is the role of the environment in natural selection?

    • The environment creates new genes in every individual
    • The environment determines which variations are advantageous
    • The environment removes all competition
    • The environment has no effect on selection

  12. Why might a population of rabbits become faster over many generations?

    • Rabbits decide to become faster by practice
    • Faster rabbits escape predators more often and pass on their genes
    • Predators make rabbits grow longer legs in their lifetime
    • Rabbits become faster because they eat more grass

  13. Which example shows competition between two organisms?

    • A plant making glucose in sunlight through photosynthesis
    • Two plants competing for light in a shaded wood
    • A bird building a nest in a tree away from other birds
    • A fish laying eggs in a pond with no other fish nearby

  14. Why do organisms compete for mates?

    • Mates prevent decomposition of dead matter
    • Successful mating allows them to pass on their genes
    • Mates provide the energy needed for photosynthesis
    • Mates supply oxygen to the lungs

  15. What is the best definition of adaptation?

    • A chemical reaction that releases energy
    • A temporary change that happens to an organism during its life
    • A feature that helps an organism survive and reproduce in its environment
    • A way of storing oxygen in cells

  16. Why might a plant with waxy leaves survive better in a dry habitat?

    • Waxy leaves release extra oxygen at night, so the plant grows more quickly
    • Waxy leaves reduce water loss, so the plant is more likely to survive
    • Waxy leaves make the plant absorb more light, so it grows faster in full sun
    • Waxy leaves prevent photosynthesis, so the plant must store food in its roots

  17. What does the phrase survival of the fittest mean?

    • Organisms with the most cells win every contest for food and territory
    • The strongest organisms are always the largest in the population studied
    • Only one organism can survive in any habitat, so the rest must die out
    • Organisms best suited to their environment are more likely to survive and reproduce

  18. What is a limiting factor in a population?

    • A factor that increases the number of organisms without limit
    • A factor that restricts population growth, such as food or space
    • A factor that makes the population evolve in a day
    • A factor that stops all photosynthesis

  19. Why do organisms that are less well adapted produce fewer offspring?

    • They stop photosynthesising at night and so lose energy each day
    • They have lower survival and reproductive success in the environment
    • They have more cells than other organisms in the same population
    • They are not allowed to reproduce by the environment around them

  20. Which statement about competition and natural selection is correct?

    • Competition prevents natural selection from happening in any population
    • Natural selection only occurs when there is no competition for resources
    • Competition can drive natural selection by favouring individuals with advantageous traits
    • Competition only occurs between different species and never within one

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