Explain why the recycling of materials is important for life on Earth to continue.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
1. Living organisms use elements such as C, H, O, N, P and S to build cells and tissues.
2. The total amount of these elements on Earth is limited and cannot be created by life.
3. When organisms die or decay, the elements are released back into the environment.
4. This return allows the elements to be reused by other organisms, sustaining life.
2. The total amount of these elements on Earth is limited and cannot be created by life.
3. When organisms die or decay, the elements are released back into the environment.
4. This return allows the elements to be reused by other organisms, sustaining life.
Examiner tips
- Use the exact wording from the mark scheme; each point counts as one mark.
- Show the causal link: finite supply → need recycling → release on death → reuse by new organisms.
- Keep each point short and to the point.
Common mistakes
- Mixing up the order of points; the sequence matters for full marks.
- Using vague terms like "nutrients" instead of the specific elements listed in the scheme.
Mark scheme (4 marks)
- Elements/materials are used by living organisms
- The supply of elements/materials on Earth is finite/limited
- Materials must be returned to the environment / released when organisms die or decay
- So that the materials can be used again by other/new organisms
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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