4(b) Feeding relationships
Pearson Edexcel International GCSE Biology · 4BI1
Paper 1 | Whole paper: Core content, all five topics
Food chains and webs, the pyramids that represent them, and why energy runs out so quickly.
Specification coverage
Topic 4 Ecology and the environment (b) Feeding relationships — statements 4.5–4.8
Assessment objectives: AO1, AO2. Suggested learning time: 55 minutes.
Required knowledge
- Food chains, food webs, and the terms producer, consumer, decomposer, herbivore and carnivore
- Pyramids of number, biomass and energy transfer
- Why the transfer of energy from one trophic level to the next is inefficient
Required skills
- Construct and interpret pyramids from data
- Predict the effect on a food web of removing one organism
- Explain why food chains rarely exceed four or five trophic levels
How it is examined
- Multiple-choice and short-answer recall
- Application of the content to an unfamiliar context
- Extended open-response, marked on the quality of a connected explanation
Common mistakes
- Drawing pyramid arrows the wrong way. Arrows show the direction of energy transfer, so they point toward the consumer.
- Saying energy is 'lost'. It is transferred to the surroundings, largely by respiration, movement and excretion.
- Expecting a pyramid of numbers always to be pyramid-shaped. A single tree supporting many insects inverts it.