What you'll learn
How living things interact in ecosystems.
Ecosystems
- Producers, consumers and decomposers; food chains and webs.
- Energy decreases up trophic levels.
- Biodiversity and competition.
Cycles
- The carbon cycle (photosynthesis, respiration, combustion, decay).
- The nitrogen cycle and nitrogen-fixing bacteria.
- Sampling with a quadrat.
Exam tips
- Explain why energy is lost between trophic levels.
- Learn how each cycle recycles nutrients.
Common mistakes
- Reversing the direction of energy flow.
- Forgetting decomposers in the cycles.