Lesson 3.1.6.2

3.1.6.2 Ecosystems and processes Quiz: AQA Geography, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.6.2, Ecosystems and processes: 20 multiple choice questions for the AQA Geography (7037), Unit 1: Physical geography, written with Revision Ninja.

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The 20 questions

  1. In a food chain, which organisms are primary producers?

    • Carnivores at the top of the chain that hunt other animals and have few natural predators
    • Herbivores that eat plants and are then eaten by carnivores higher up the chain in most habitats
    • Plants and algae that fix energy through photosynthesis and form the base of the chain
    • Decomposers that break down dead matter and return nutrients to the soil for reuse by plants

  2. What is a trophic level?

    • The position an organism occupies in a food chain, based on its feeding relationship
    • The rate of soil formation in a region, which depends on weathering and biological activity
    • The temperature range of a biome, measured across the year and averaged over several decades
    • The depth of a lake at which light stops penetrating and photosynthesis can no longer take place

  3. Approximately what percentage of energy is typically transferred from one trophic level to the next?

    • About 50 per cent, which is shared between the consumer and the decomposers at each level
    • About 1 per cent, because almost all energy is stored in the producers and never reaches consumers
    • About 10 per cent, with the remainder lost mainly as heat through respiration
    • About 90 per cent, since most energy is passed on to the next trophic level in the food chain

  4. Which term describes the total amount of organic matter in a given area at a point in time?

    • Net primary production, which is the energy stored by producers after their own respiration is subtracted
    • Succession, which is the gradual change in species composition in a community over a long period
    • Climatic climax, which is the stable final community that a region's climate supports over time
    • Biomass

  5. Net primary production is best described as:

    • Gross primary production minus the energy used by producers in respiration
    • The total energy captured by all consumers in a food web, including the energy lost as heat at each level
    • The energy lost from the system as heat only, measured at the end of the food chain over a year
    • The mass of dead matter in the soil that has not yet been decomposed by bacteria and fungi

  6. Which of these is an example of a store in an ecosystem?

    • Carbon held in the trunk of a tree for decades
    • Nutrients being moved by a food web as organisms consume and excrete material in the ecosystem
    • Water evaporating from a lake surface and rising into the atmosphere during warm weather
    • Energy flowing between trophic levels as animals eat plants and other animals in the food web

  7. Which of these is a transfer within an ecosystem?

    • Energy stored in the soil as organic matter from roots and dead plant material over many years
    • Biomass accumulated in a mature forest over several centuries of growth and development
    • Nutrients moved from dead leaves into the soil by decomposers
    • Carbon locked in limestone for millions of years, forming a store that is rarely disturbed

  8. Which concept describes a sequence of changes in an ecosystem over time, moving towards a stable community?

    • Succession
    • Mineral nutrient cycling, which describes the circulation of minerals between living organisms and the soil
    • Biome shift, which describes the movement of major vegetation zones in response to climate change
    • Trophic cascade, which describes indirect effects on lower trophic levels when a predator is removed

  9. A seral stage is best described as:

    • A measure of the energy flow in a food web, expressed as the total joules transferred between levels
    • A single species that dominates a biome permanently and prevents any other species from becoming established
    • A stage in a succession sequence, with a characteristic community of plants and animals
    • A type of soil that forms on bedrock after many years of weathering and biological activity in the area

  10. A climatic climax is:

    • The stable, final community that a region's climate would support on well-drained soils without human interference
    • A short-lived pioneer community on bare rock that is quickly replaced by more competitive species
    • A community maintained permanently by grazing animals, which prevents woodland from establishing
    • A community that appears briefly after a fire and disappears within a year as the vegetation is replaced

  11. A plagioclimax differs from a climatic climax because it:

    • Develops on bare rock with no soil and is composed of lichens and mosses that cannot be replaced
    • Forms only in tropical rainforests where high rainfall and warm temperatures favour dense vegetation
    • Has no plant cover at all, because it is a community that has been stripped of vegetation by erosion
    • Is maintained by human activity or other factors, such as grazing or burning, rather than climate alone

  12. Which process is a key part of mineral nutrient cycling?

    • Volcanic ash fall that adds sulphur dioxide to the air, which then reaches the soil in acid rain
    • Continental drift that moves minerals to new locations across the Earth's surface over millions of years
    • Decomposition of litter, releasing nutrients back into the soil
    • Evaporation of ocean water into the atmosphere, which transfers salt and minerals to the land

  13. An ecosystem's energy input is primarily:

    • Geothermal heat from the Earth's core, which warms the soil and water across most ecosystems
    • Chemical energy released from volcanic gases, which supports ecosystems near active vents
    • Tidal forces from the Moon, which move water and energy between the land and sea in coastal habitats
    • Solar radiation captured by producers

  14. Which factor most strongly controls the structure of terrestrial ecosystems at a regional scale?

    • Only the depth of the ocean nearby, which determines the type of plants that can grow on the coast
    • Only the number of volcanoes in the region, which determines the fertility of the soils across the area
    • Climate, including temperature and precipitation, with soil and topography modifying its effects
    • Only the presence of humans in the region, whose land use decisions determine the type of vegetation present

  15. Which statement about climate change and ecosystems is most accurate?

    • Climate change only affects ocean ecosystems, since terrestrial ecosystems are protected by the soil and vegetation
    • Changes in temperature and rainfall can shift ecosystem boundaries and alter species composition
    • Climate change has no effect on ecosystem boundaries, which are fixed by the underlying geology of the region
    • Climate change always increases biomass everywhere, because warmer conditions favour plant growth in every region

  16. Which of these is an example of a system input for an ecosystem?

    • Water lost by transpiration from the leaves of plants into the atmosphere
    • Nutrients leaving through leaching as rainwater carries them down through the soil profile
    • Solar energy entering the ecosystem
    • Heat leaving through respiration as organisms use energy for their metabolism

  17. Which factor best explains why a mature woodland has a larger biomass than a young woodland in the same location?

    • Young woodlands are always taller than mature ones, because they grow faster and are not limited by age
    • Young woodlands receive more solar energy per tree because the canopy is less dense and light is more abundant
    • Mature woodlands have no decomposers, so organic matter is retained and stored in the trees for longer
    • Accumulated growth over many years allows more organic matter to build up

  18. Which statement best evaluates the view that ecosystems always move towards a fixed climatic climax?

    • Succession never occurs in any ecosystem, since communities remain fixed once they have become established
    • Succession can be interrupted by disturbance or human activity, so ecosystems do not always reach the climatic climax
    • Every ecosystem reaches the climatic climax within a single year of the initial colonisation of the site
    • The climatic climax is always the first stage of succession, which is then followed by pioneer communities

  19. A plant produces 500 units of gross primary production and uses 200 units in respiration. What is its net primary production?

    • 300 units
    • 200 units, which is the energy used in respiration that is lost from the plant and not stored
    • 700 units, which is the sum of gross production and the energy used in respiration by the plant
    • 500 units, which is the same as gross production because respiration does not affect the net total

  20. Which of these best illustrates the concept of a biogeochemical cycle within an ecosystem?

    • A volcano erupting once every hundred years, releasing gases that remain in the atmosphere for a long time
    • A single organism moving from one habitat to another during its migration over several seasons
    • Water flowing downhill in a river without evaporation, reaching the sea without returning to the land
    • Carbon moving from the atmosphere into plants through photosynthesis and back to the atmosphere through respiration

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