GCSE Biology · AQA 8461 · Topic 4.7
Ecology
Key points
- An ecosystem is the interaction of a community of living organisms with the non-living parts of their environment.
- Organisms compete for resources and are adapted to their conditions; changes in one population affect others (interdependence).
- Materials such as carbon and water are recycled; decomposers return mineral ions to the soil.
- Biodiversity is threatened by human population growth, waste, land use, deforestation and global warming.
- Energy is lost between trophic levels, so biomass decreases up a food chain.
- Food security depends on sustainable food production, including fishing quotas and biotechnology.
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No organism lives in isolation: every plant, animal and microorganism depends on others and on its physical surroundings. Ecology studies these relationships, how materials cycle through ecosystems, and how human activity is changing the…
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