Describe how trophic levels are organised in a food chain and explain why producers are described as providing biomass for all living things.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
A trophic level is the position of an organism in a food chain.
Producers occupy the first trophic level – they are at the start of the food chain.
Producers are photosynthetic organisms that use light energy to produce organic material, i.e. biomass.
All other organisms (consumers) obtain biomass by eating producers or organisms that have eaten producers, so all biomass in the food chain originates from producers.
Producers occupy the first trophic level – they are at the start of the food chain.
Producers are photosynthetic organisms that use light energy to produce organic material, i.e. biomass.
All other organisms (consumers) obtain biomass by eating producers or organisms that have eaten producers, so all biomass in the food chain originates from producers.
Examiner tips
- Use the term "trophic level" and state it is a position in a food chain. Mention that producers are at the first level. Explain that they are photosynthetic and convert light energy into biomass. Show the chain of biomass transfer from producers to consumers.
Common mistakes
- Confusing producers with consumers. Failing to mention that producers use light energy. Lacking the link that all biomass originates from producers.
Mark scheme (4 marks)
- A trophic level is the position of an organism in a food chain
- Producers are at the first trophic level / start of the food chain
- Producers are photosynthetic organisms that use light energy to produce organic material / biomass
- All other organisms (consumers) obtain biomass by eating producers or organisms that have eaten producers, so all biomass in the food chain originates from producers
Key terms in this question
trophic level · producer · biomass · food chain
Related
- Revision notes: Trophic levels in an ecosystem (Bio only) →
- How to answer a "Describe and Explain" question →
- Decode the mark scheme abbreviations →
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