Pearson Edexcel International GCSE Biology · specification 4BI1 · Paper 1 | Whole paper: Core content, all five topics · Free · no account needed
4(b) Feeding relationships (4BI1 specification)
Food chains and webs, the pyramids that represent them, and why energy runs out so quickly.
Learn it on Incandio
The 3 Incandio pages that teach this — each explained in full, then proved in marked questions, taught back to an AI pupil and defended in a debate. Completely free.
- Biodiversity, Distribution and Limiting Factors — Why organisms are where they are and not somewhere else — and how to measure the variety of life in a place rather than just its quantity.
- Food Chains, Webs and Pyramids — Who eats whom, drawn three different ways — and why only one of the three can come out upside down.
- Energy Transfer Along a Food Chain — About nine tenths of the energy disappears at every step. Here is exactly where it goes — and what that means for how the world is fed.
The teaching route this belongs to: Topic 4 · Ecology and the environment (Biology) — the lessons in order, with every gate.
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.
This page maps the specification. The pages above teach it, and the Biology lessons hold the whole course — completely free.