Lesson 3.7.4.1

3.7.4.1 Niches, habitats and competition Quiz: AQA Biology, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.7.4.1, Niches, habitats and competition: 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 a niche?

    • The total number of species present in an ecosystem, counted across all the habitats that make up the community in that area
    • The physical place where a species lives, including the soil, water and air that surround the organisms that are found there
    • The interaction between two predators that hunt the same prey, which determines how many individuals of each species can survive
    • The role of a species in its habitat, governed by its adaptations to abiotic and biotic conditions

  2. What is a habitat?

    • The total population of a species
    • The role an organism plays in its community
    • The place where an organism lives
    • The number of species present in a community

  3. What is meant by the carrying capacity of an ecosystem?

    • The maximum rate at which a population can grow
    • The largest population size that an ecosystem can support over time
    • The number of predators that a habitat can hold
    • The total biomass of all producers in the ecosystem

  4. Intraspecific competition is:

    • Competition between individuals of the same species
    • Competition between populations in different habitats
    • Competition between individuals of different species
    • Competition between plants and animals only

  5. A community is best defined as:

    • All the non-living components of an environment
    • Populations of different species living together in the same area
    • The area occupied by one ecosystem
    • A single population of one species

  6. Which sampling method is used for slow-moving or non-motile organisms?

    • Mist netting for birds, which are caught in fine nets so that they can be ringed and released in the same place after sampling
    • Randomly placed quadrats or quadrats along a belt transect
    • Mark-release-recapture, in which animals are caught, marked, released and then caught again to estimate the size of the population
    • Pitfall traps only, which are sunk into the ground so that small animals fall in and are counted once they have been caught

  7. Which method is used to estimate the size of a motile population?

    • Random quadrats
    • Mark-release-recapture
    • Belt transects
    • Percentage cover measurements

  8. In a mark-release-recapture study, 50 animals are marked and released. A second sample of 40 contains 10 marked animals. Using the Lincoln index N = (M x n) / m, what is the population estimate?

    • 2000
    • 8
    • 200
    • 125

  9. Which is an assumption of mark-release-recapture?

    • Marked individuals are more likely to be caught in the second sample
    • Marked individuals mix randomly with the unmarked population
    • Births and deaths occur only in the marked group
    • The marks are removed from the animals before the second sample

  10. In a survey, what does percentage cover measure?

    • The number of individuals per square metre
    • The number of species in the whole habitat
    • The proportion of quadrats in which a species is present
    • The proportion of an area covered by a species

  11. Which is the correct order of stages in primary succession?

    • Pioneer species, intermediate communities, then a climax community
    • Pioneer species, then climax community, with no intermediate stages
    • Climax community, then pioneer species, then intermediate communities
    • Intermediate communities, then climax community, then pioneer species

  12. Which of these is an abiotic factor that can change population size?

    • Disease transmitted between individuals
    • Predation
    • Temperature
    • Competition for food

  13. What is interspecific competition?

    • Competition for light between plants of one species only
    • Competition between individuals of the same species for mates
    • Competition between individuals of different species for the same limited resource
    • Competition between predators for the same food in one habitat

  14. A student counts 12 daisies in 10 quadrats, each of area 0.25 m2. What is the density of daisies in the area sampled?

    • 48 per m2
    • 0.48 per m2
    • 1.2 per m2
    • 4.8 per m2

  15. Predation can affect a population of prey. What is the most direct effect?

    • Individuals are killed, which can reduce the prey population size
    • Predators always become extinct when prey are removed
    • Prey populations always increase because predators limit competition
    • Predation has no effect on prey population size

  16. Why can two species not occupy exactly the same niche for long in one habitat?

    • Identical niches always produce two stable populations with equal numbers, because the two species then share the same resources equally
    • Niche overlap never affects population size, since each species regulates its own numbers independently of the other species present
    • Species with identical niches always breed at different times of year and so avoid competition for food and shelter completely
    • Competition for the same limited resources means one species is usually eliminated, according to competitive exclusion

  17. A quadrat survey finds a species is denser in one half of a field. Which criticism is most important?

    • The field has no abiotic factors that could affect the species
    • The quadrats were too small to contain any organisms
    • The quadrats may not have been placed randomly, so the result may be biased
    • Quadrat surveys can only be used in ponds

  18. A mark-release-recapture study marks 30 animals. The second sample contains 50 animals, of which 5 are marked. What is the population estimate?

    • 30
    • 500
    • 60
    • 300

  19. Why does ecological succession occur?

    • Succession happens only when humans clear vegetation from an area, so natural habitats never change in composition over time
    • Each species is permanently fixed in one habitat and never changes it, so the community stays the same once it has become established
    • Succession occurs because all climax communities are identical in species, so every habitat moves towards the same single community
    • Each species changes the environment so that other species with different adaptations can replace it

  20. A population exceeds the carrying capacity of its ecosystem. What is the most likely outcome?

    • The population falls because resources become limiting and deaths exceed births
    • The population doubles because competition stops
    • The population continues to grow because the carrying capacity has increased
    • The carrying capacity disappears and the population stays fixed

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