Levels of organisation — AQA GCSE Biology
Test yourself on Levels of organisation with AQA GCSE practice questions.
7 days Premium · Then free forever · No card, no charge
Levels of organisation explained
A producer is an organism that makes its own organic nutrients, usually by photosynthesis.
Read the full explanation
Producers synthesise molecules such as glucose from carbon dioxide and water using light energy, and they build these molecules into carbohydrates, proteins and lipids that form their biomass. Because producers do not need to eat other organisms to obtain carbon, they occupy the first trophic level of every food chain. Consumers obtain their carbon and energy by eating producers or other consumers, so all food chains depend on the molecules synthesised by producers. In a few ecosystems, chemosynthetic bacteria act as producers, but the principle is the same: the first organism in the chain makes its own organic molecules.
Your focus
- Define a producer and explain why it is the first organism in a food chain.
- Describe how producers synthesise biological molecules.
- Explain why consumers depend on the molecules synthesised by producers.
Levels of organisation exam tips
Marking Points
- A producer is an organism that synthesises its own organic molecules, usually by photosynthesis.
- Producers use carbon dioxide, water and light energy to make glucose and other biological molecules.
- Producers occupy the first trophic level of a food chain.
- Consumers depend on the molecules made by producers because they cannot make their own organic nutrients in the same way.
- Some producers, such as chemosynthetic bacteria, synthesise molecules without light, but they still form the base of their food chain.
Examiner Tips
- 💡Name the producer in a given food chain and state that it synthesises molecules by photosynthesis.
- 💡Use the phrase 'first trophic level' when identifying the position of the producer.
- 💡If a food chain is shown, check that it starts with a producer before describing the consumers.
Common Mistakes
- Thinking the producer is always the largest organism; correction: producers are defined by how they obtain nutrients, not by size.
- Saying producers take in food from the soil; correction: producers synthesise organic molecules, although they do absorb water and mineral ions from the soil.
- Forgetting that the arrow from a producer points to the consumer that eats it; correction: the arrow shows the direction of energy transfer, from producer to consumer.