Fiducia TogetherFood chains and ecosystems
What eats what, and where the energy goes.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
A food chain shows feeding relationships: producer → primary consumer → secondary consumer. Trophic levels are the positions in it. A food web links several chains.
Where it applies
GCSE biology and combined science, and it overlaps with geography.
How it works
Only about 10% of energy transfers between trophic levels; the rest is lost to respiration, movement and waste. That is why food chains are short and why there are fewer top predators.
Biodiversity, interdependence and the effects of removing one species are common question territory.
How to use it in your work
When asked why energy is lost, give the specific routes — respiration, movement, egestion, excretion — not just "it is lost".
For "what happens if X is removed", trace effects both up and down the chain, and mention that other species may be affected indirectly.
Where to get help
Your teacher, your board's specification for the depth required at your tier, and Bitesize for the diagrams. The subject song runs the topics in order.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Biology Song The GCSE biology specification, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.