ReviseRush logoREVISERUSH

AQA GCSE Geography

Ecosystems, rainforests and hot deserts — AQA GCSE Geography revision

Free revision notes, key terms, common exam traps and 5 practice questions with answers. About 8 minutes to read.

Ecosystem basics

  • An ecosystem links biotic (living) and abiotic (non-living) components through food chains, food webs and nutrient cycles; changing one component causes knock-on effects throughout.
  • Producers convert sunlight to energy, consumers eat other organisms and decomposers return nutrients to the soil. Energy is lost at each trophic level, so pyramids narrow upwards.
  • Global biomes (rainforest, savanna, desert, temperate forest, taiga, tundra) are distributed largely by global atmospheric circulation, latitude and continentality.

Tropical rainforests

  • Hot (25-30°C) and wet (over 2000 mm/yr) all year with rapid nutrient cycling: most nutrients are stored in biomass, not the thin, leached soil.
  • Adaptations: buttress roots for stability, drip-tip leaves to shed water, lianas and epiphytes to reach light, emergent and canopy layering; animals show camouflage, nocturnal habits and specialised diets.
  • Deforestation causes: logging, cattle ranching, soya and palm oil, mineral extraction, road building, hydroelectric dams, population pressure. Impacts include biodiversity loss, soil erosion, reduced rainfall and carbon release; management includes selective logging, replanting, ecotourism, debt-for-nature swaps and international agreements.

Key terms

Biotic
The living parts of an ecosystem.
Abiotic
The non-living parts, such as climate, soil and water.
Nutrient cycle
The movement of nutrients between biomass, litter and soil stores.
Biodiversity
The variety of plant and animal species in an ecosystem.
Deforestation
The permanent clearing of forest for other land uses.
Selective logging
Removing only mature or selected trees so the forest structure recovers.

Common exam traps

  • Saying rainforest soils are rich — they are thin and leached; the nutrients are in the biomass.
  • Listing 'hot' as a rainforest adaptation instead of describing a plant or animal feature.
  • Confusing desertification (land degradation) with drought (a temporary rainfall deficit).

Practice questions with answers

  1. 1. Which is an abiotic component of an ecosystem?

    • • Fungi
    • • Rainfall
    • • Insects
    • • Trees

    Answer: Rainfall

    Abiotic means non-living — climate, soil, water, light.

  2. 2. Explain what happens to a food web if a top predator is removed.

    Answer: Prey numbers rise, over-grazing plants, so producer numbers fall and the web becomes unbalanced

    Show a chain of consequences, not a single statement.

  3. 3. Where are most nutrients stored in a tropical rainforest?

    • • Soil
    • • Litter
    • • Biomass
    • • Groundwater

    Answer: Biomass

    Rapid uptake by plants keeps nutrients in living matter.

  4. 4. Drip-tip leaves are an adaptation to:

    • • Reduce water loss
    • • Shed heavy rainfall quickly
    • • Capture insects
    • • Store nutrients

    Answer: Shed heavy rainfall quickly

    Fast drainage prevents fungal growth and leaf damage.

  5. 5. Give two causes of deforestation in tropical rainforests.

    Answer: Cattle ranching and commercial logging (also mining, soya, roads, HEP)

    Economic drivers dominate rainforest clearance.

Keep going in the app

This topic has 51 questions in total, plus flashcards, cram mode and Grade 9 Push challenges.

Open the full topic Quick-fire quiz

More free Geography revision

ReviseRush is an independent educational revision aid. It is not affiliated with, endorsed by or connected to AQA, Edexcel, OCR, WJEC, Pearson or any exam board. All notes and questions are original. Always check content against your official course and specification. No grade outcome is guaranteed.