Food chains and trophic levels

Feeding relationships within a community can be represented by food chains.
All food chains begin with a producer, which synthesises molecules (usually a green plant or algae) that makes glucose via photosynthesis. Producers are eaten by primary consumers, which may be eaten by secondary consumers and then tertiary consumers.
Trophic levels refer to the position an organism occupies in a food chain. Trophic levels can be represented by numbers according to how far an organism is along the food chain.
- Level 1: producers like plants and algae make their own food via photosynthesis.
- Level 2: primary consumers are herbivores that eat producers.
- Level 3: secondary consumers are carnivores or herbivores that eat primary consumers.
- Level 4: tertiary consumers are carnivores that eat secondary consumers.
- Apex predators: are at the top of the food chain and have no predators.
Decomposers: break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then diffuse into the microorganism. This also releases mineral ions and nutrients that plants can absorb from the soil. Examples include bacteria, fungi, and worms.

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