Explain why a stable ecosystem such as a coral reef is able to support a large number of different species.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A coral reef is a complex ecosystem containing hundreds of species of fish, invertebrates, algae and microorganisms. Scientists describe it as having high biodiversity.
Model answer (4 marks)
A coral reef can support many species because it contains many different food sources and complex feeding relationships. Energy enters the system through producers such as algae, which are eaten by primary consumers and then by higher‑level consumers, forming a food web that transfers energy between species. Organisms occupy different niches or roles, which reduces competition and allows many species to coexist. Finally, decomposers recycle materials and nutrients, keeping the environment self‑sustaining and suitable for life.
Examiner tips
- Use the word ‘food web’ to show understanding of energy flow.
- Mention both producers and decomposers to cover all parts of the mark scheme.
Common mistakes
- Failing to mention producers or decomposers.
- Using vague terms like ‘lots of species’ without explaining the mechanisms.
Mark scheme (4 marks)
- A large number of different food sources / feeding relationships exist in the ecosystem
- Energy enters the ecosystem through producers (e.g. algae) which are eaten by consumers, transferring energy through the food web
- Organisms occupy different niches / roles so competition between species is reduced, allowing more species to coexist
- The ecosystem is self-sustaining because materials / nutrients are recycled by decomposers, maintaining conditions for life
Key terms in this question
Related
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- Decode the mark scheme abbreviations →