Producers and consumers, predator and prey cycles, the carbon, water and nitrogen cycles, what speeds up decay, and the milk and lipase decay practical with rate = 1000 ÷ time (Biology only).
What you will learn
- Name the roles in a food chain
- Read a predator-prey graph and explain the lag
- Describe the carbon cycle and the water cycle
- Describe the nitrogen cycle and the bacteria in it (Edexcel)
- Calculate a rate of decay and spot an anomaly (Biology only)
Food chains and predator-prey cycles
Every chain starts with a producer (a plant or alga that photosynthesises), then the primary consumer (herbivore), secondary and tertiary consumers.
The arrows point the way the biomass goes. The top carnivore is the apex predator.
Predator and prey numbers rise and fall in cycles. Plenty of prey means the predators breed and increase; then they eat more prey, the prey fall, and the predators fall soon after. The predator peaks come after the prey peaks.
The rest of this lesson and its 15 practice questions are locked.
In this lesson
- Food chains and predator-prey cycles
- The carbon and water cycles
- The nitrogen cycle (Edexcel)
- Required practical: rate of decay (Biology only)
- Try it: Your first chain
15 practice questions, marked as you go; about 25 minutes in all.
Key terms
Producer, Primary consumer, Secondary, Tertiary consumers, Apex predator, After, Nitrate ions, Nitrogen-fixing, Denitrifying
In this unit: Ecology
Communities and adaptations, sampling with quadrats, transects and capture-recapture, food chains and the carbon, water and nitrogen cycles, decay, parasitism and mutualism, eutrophication, biodiversity and human impact, biomass transfer and food security.
- Communities, interdependence and adaptations
- Sampling with quadrats, transects and capture-recapture
- Food chains, cycles and decay
- Biodiversity and human impact
- Trophic levels, pyramids and efficiency
- Food security and farming
- Biological control and bioaccumulation
- Fish farming, introduced species and the cycles in depth