Fiducia TogetherEnzymes
Biological catalysts. Specific, and easily destroyed.
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
Enzymes are proteins that speed up reactions without being used up. Each has an active site shaped to fit one substrate — the lock and key model, refined by the induced fit model.
Where it applies
GCSE biology and combined science, and a required practical.
How it works
Rate rises with temperature until the enzyme denatures — the active site changes shape and no longer fits. pH has an optimum for the same reason.
Denaturing is permanent. Enzymes are not "killed"; they are proteins and they unfold.
How to use it in your work
Never write that an enzyme is killed. It is not alive. Say denatured, and say the active site changes shape so the substrate no longer fits — that phrase is the mark.
On a rate graph, explain both sides of the peak, with different reasons: more kinetic energy before, denaturing after.
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.