Enzyme

Definition

A biological catalyst that speeds up a reaction without being used up.

Used by Edexcel and OCR

Specification 7.8, 9.33C · Paper 2

A biological catalyst: a substance made by living organisms that speeds up a reaction without being used up.
An enzyme is a biological catalyst, made by a living organism. Enzymes allow reactions in living things to happen faster.
Revise: Enzymes
A biological catalyst that increases the rate of a reaction without being used up.
Revise: Fermentation

1
Do not call yeast an enzyme: yeast is a microorganism that contains enzymes.
2
Link alcoholic drinks to fermentation: yeast enzymes catalyse the conversion of sugars into ethanol and carbon dioxide.
3
Do not write yeast or enzymes as reactants: yeast supplies enzymes that catalyse the reaction.

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Specification C5.2i · Paper 2 (Foundation), Paper 4 (Higher)

A protein that acts as a catalyst in a biological system.
An enzyme is a protein that acts as a catalyst in a biological system, such as a living cell. Enzymes are therefore biological catalysts: they do the same essential job as other catalysts, but in the reactions of living things. For example, enzymes speed up reactions involved in digestion and respiration.
Revise: Enzymes

Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)

A catalyst produced by living organisms that increases the rate of a biological reaction.
Enzymes are biological catalysts. They allow the many reactions needed by living organisms to occur quickly under relatively mild conditions, without the enzyme being used up overall. Like other catalysts, enzymes are usually specific to particular reactions.
Revise: Catalysts
A protein that acts as a catalyst in a biological reaction.
Revise: Enzymes