Edexcel IGCSEBiologyGeneral Applications7 Marks
Enzymes are biological catalysts that control the rate of metabolic reactions.
- (a)Describe an experiment to investigate the effect of temperature on the rate of enzyme activity.[4]
- (b)Explain the effect of very high temperatures on enzyme activity.[3]
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- M1 for specific enzyme and substrate e.g. amylase and starch
- M1 for method to measure reaction rate e.g. time for starch to disappear (iodine test) / measure product formation (gas production)
- M1 for use of a range of temperatures (at least 3 different temperatures specified)
- A1 for controlled variables mentioned e.g. pH, enzyme concentration, substrate concentration, volume of reagents
- M1 for enzyme denatures / active site changes shape
- M1 for substrate can no longer fit into active site / enzyme-substrate complex cannot form
- A1 for enzyme permanently loses its function / activity drops to zero / irreversible
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