A-LevelBiologyEnzymesOct/Nov 2020Paper 1 Q131 Mark
Lipase is an enzyme that catalyses the hydrolysis of lipids. An experiment was carried out to investigate changes in pH when lipase is added to a food sample containing a high proportion of lipids. The results are shown in the graph. [Figure 13.1] Which statements are possible explanations of the results of the experiment between 50 minutes and 60 minutes? 1 Enzyme concentration becomes the limiting factor. 2 Substrate concentration becomes the limiting factor. 3 All the enzyme active sites are occupied. 4 Denaturation of the enzyme by the products takes place. 5 Products are acting as competitive inhibitors.
A1, 2 and 3
B1, 4 and 5
C2, 3 and 4
D2, 4 and 5
✓ Correct Answer
The correct answer is D: 2, 4 and 5
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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