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CIE IGCSE Biology: Enzymes


Catalyst: a substance that speeds up a chemical reaction and is not changed by the reaction.
Enzymes: proteins that function as biological catalysts.

The enzyme action:

1. The substrate molecule fits onto the active site of the enzyme.
2. The substrate molecule has a…

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CIE IGCSE Biology: Enzymes

(protease) that works in the stomach at a very low pH ­ pH2 which is why the stomach secretes hydrochloric acid.
Amylase works best at pH 7 or slightly above and is found in the mouth.

Germination of Seeds
1. The seed contains the following enzymes:…

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CIE IGCSE Biology: Enzymes

The use of microorganisms and fermenters to manufacture the antibiotic penicillin and enzymes
for use in biological washing powders:

In a fermenter, the microorganism grows in a liquid called the medium. The medium must contain everything that the
microorganism needs to live and produce the desired…

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CIE IGCSE Biology: Enzymes

3. Bacteria provided with oxygen for aerobic respiration
4. Optimum temperature (26°C) and optimum pH 56 are set
5. The mixture is stirred to prevent settling
6. Bacteria grow and reproduce rapidly
7. Bacteria/fungi secret enzymes ­ either intracellular which are obtained by filtering the bacteria/fungi…


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