Explain why a woodland ecosystem is described as self-sustaining.

Eduqas GCSE Biology — 1.6.1 Ecosystems · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A woodland contains producers, consumers, decomposers and abiotic factors such as soil, water and sunlight. Together, these components interact to keep the woodland functioning without human intervention.

Model answer (4 marks)

Producers in the woodland use sunlight to photosynthesise, producing organic molecules that form the food for the whole ecosystem.
Energy and matter are transferred through the food chain as organisms eat one another.
Decomposers break down dead plants and animals, returning nutrients and minerals to the soil.
These nutrients are then taken up again by producers, so the materials are continually recycled and the woodland does not run out of resources.

Examiner tips

Use the word ‘photosynthesise’ and mention sunlight. Show the flow of energy through feeding relationships. Explain the role of decomposers in nutrient recycling. Link recycling back to the self‑sustaining nature of the ecosystem.

Common mistakes

Confusing producers with consumers. Omitting the role of decomposers. Failing to mention nutrient recycling.

Mark scheme (4 marks)

Producers photosynthesise / use sunlight to produce organic molecules / food
Energy / matter is passed through the ecosystem via feeding relationships / food chains
Decomposers break down dead organic matter, returning nutrients / minerals to the soil
Nutrients are continuously recycled / reused by producers, so the ecosystem does not run out of materials

Key terms in this question

self-sustaining