Ecosystems - AQA GCSE Geography (Paper 1) Exam Questions

Practise 34 exam-style questions on Ecosystems for AQA GCSE Geography (Paper 1). Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.

34 questions
1–12 marks each
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20 questions, marked as you go

Sample questions with model answers

Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.

Question 1

1 mark

Which one of the following large-scale ecosystems is found mainly between about 15° and 30° north and south of the Equator?

A Tropical rainforest
B Hot desert
C Tundra
D Temperate deciduous forest

Give the letter of the correct answer.

Model answer

Explanation

Hot deserts such as the Sahara and the Kalahari lie near the Tropics of Cancer and Capricorn, where sinking air creates high pressure and very little rain. Tropical rainforests are near the Equator, temperate deciduous forests at about 40-60°N, and tundra in the far north.

Mark scheme

1 mark
B (hot desert)
accept the letter or the option written out; do not accept more than one answer

Question 2

2 marks

Suggest two ways in which human activity can change a small-scale ecosystem in the UK, such as a pond or a hedgerow.

Model answer

Fertiliser can run off nearby fields into a pond, causing algae to grow rapidly, and farmers may remove hedgerows to make bigger fields for machinery.

Explanation

Human changes can be negative (pollution, drainage, removing habitats, introducing invasive species) or positive (conservation such as creating ponds or replanting hedgerows). Any two clearly different ways are credited.

Mark scheme

1 mark
Fertiliser running off farmland into a pond causes eutrophication (algal blooms)
max 2; 1 mark per way
1 mark
Draining or filling in ponds for farming or building
1 mark
Removing hedgerows to make larger fields
1 mark
Introducing non-native species, e.g. signal crayfish or Himalayan balsam
1 mark
Pollution, e.g. litter, oil or chemicals from roads
1 mark
Spraying pesticides or herbicides that kill insects or plants
1 mark
Cutting hedges at the wrong time of year (e.g. during bird nesting)
1 mark
Conservation work, e.g. creating new ponds or planting hedges
accept positive changes

Question 3

4 marks

Explain how the introduction of a non-native species can affect a small-scale ecosystem in the UK.

Model answer

Non-native species often have no natural predators in the UK, so their numbers can grow very quickly and they compete with native species. For example, Himalayan balsam, a plant introduced from Asia, grows tall and dense along riverbanks and pond edges, shading out native plants so that they die. Insects and other animals that depended on those native plants then lose their food, so biodiversity falls. In winter the balsam dies back, leaving the banks bare, so they are easily eroded by water. In this way one introduced species can upset the balance of the whole ecosystem.

Explanation

Level 2 traces the effect beyond the first step: the invader outcompetes a native species, and that change then affects other parts of the food web or the physical environment. A named example, such as grey squirrels, signal crayfish or Himalayan balsam, makes the answer specific.

Mark scheme

4 marks
Levels of response (4 marks).
Level 2 (3-4 marks): clear explanation of how a non-native species affects other components of the ecosystem, with developed chains of effects; may use a named example.
Level 1 (1-2 marks): basic statements, e.g. it kills native species, with little explanation.
0 marks: nothing worthy of credit.
Indicative content (not a checklist; credit other valid points): non-native species often have no natural predators or diseases, so their numbers increase rapidly; they compete with native species for food, light or space; grey squirrels, introduced from North America, outcompete native red squirrels for food and carry squirrelpox, which kills reds; signal crayfish carry crayfish plague, which kills native white-clawed crayfish, and burrow into riverbanks, causing erosion; Himalayan balsam grows tall along rivers and ponds and shades out native plants, then dies back in winter leaving banks bare and easily eroded; Japanese knotweed spreads rapidly; native species decline, reducing biodiversity; food webs change because species that depended on the native species lose a food source; the balance of the ecosystem is upset; management (e.g. removal) is costly.

Question 4

6 marks

Explain how energy flows and nutrients are cycled in a small-scale UK ecosystem you have studied.

Model answer

In the freshwater pond I studied, energy enters the ecosystem as sunlight. Producers such as algae, pondweed and reeds capture this energy through photosynthesis and use it to grow. The energy then passes along food chains when organisms are eaten: algae are eaten by water fleas, which are eaten by sticklebacks, which are eaten by pike or herons. Many of these food chains are linked to form a food web. At each stage, most of the energy is used for movement and growth or lost as heat and waste, so only about 10% passes on to the next level. This is why there are many water fleas but only one or two herons visiting the pond. Energy flows through the ecosystem in one direction and is not recycled.

Nutrients, however, are recycled. Plants take up nutrients such as nitrates dissolved in the pond water and from the mud. These nutrients pass to animals when they feed. When plants and animals die, or when animals produce waste, the material sinks to the bottom of the pond. Decomposers such as bacteria and fungi break it down, releasing the nutrients back into the water and mud, where plants can absorb them again. Leaves falling from trees around the pond in autumn add extra nutrients. In this way the same nutrients are used over and over again.

Explanation

The key distinction is that energy flows (in one direction, with losses at each level) while nutrients cycle (they are reused). Level 3 explains both processes clearly using named producers, consumers and decomposers from a specific ecosystem.

Mark scheme

6 marks
Levels of response (6 marks).
Level 3 (5-6 marks): detailed, well-developed explanation of both energy flow (producers, consumers, food chains and webs) and nutrient cycling (stores, decomposers); clear understanding that energy flows through and is lost while nutrients are recycled; detailed reference to a named small-scale UK ecosystem with named species.
Level 2 (3-4 marks): clear explanation of energy flow and/or nutrient cycling with some development; some specific detail of a named example.
Level 1 (1-2 marks): basic statements with little explanation; generic, not related to a named example.
0 marks: nothing worthy of credit.
Indicative content (not a checklist; credit other valid points): energy enters the ecosystem as sunlight, captured by producers through photosynthesis (e.g. algae and pondweed in a pond; oak, beech and bluebells in a woodland); energy passes to primary consumers (herbivores, e.g. water snails, mayfly larvae, caterpillars), then to secondary and tertiary consumers (e.g. sticklebacks, newts, pike, herons; blue tits, sparrowhawks); food webs show many interlinked chains; at each trophic level most energy is lost as heat, movement and waste, so only about 10% passes on and there are fewer top consumers; energy flows in one direction and is not recycled; nutrients are recycled: plants take up nutrients from soil or water; nutrients pass to consumers when they eat; dead plants and animals, fallen leaves and waste form litter; decomposers (bacteria, fungi) and detritivores (earthworms, woodlice) break this down, releasing nutrients back into the soil or water to be taken up again; in a deciduous woodland, autumn leaf fall supplies the litter; nutrients are added by rain and weathering and lost by leaching; credit any appropriate named example.

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