A-LevelBiologyEnzymesOct/Nov 2017Paper 1 Q151 Mark
An experiment was carried out in which the enzyme lipase was used to hydrolyse a triglyceride. The pH was recorded at regular intervals during the reaction. The results are shown in the table. [Figure 15.1 - table of pH changes over time during lipase reaction] At 14 minutes unreacted triglyceride was still present. What explains the results after 10 minutes?
AThe end-products acted as competitive inhibitors.
BThe end-products acted as non-competitive inhibitors.
CThe enzyme reaction had reached Vmax.
DThe tertiary structure of the enzyme had been lost.
✓ Correct Answer
The correct answer is D: The tertiary structure of the enzyme had been lost.
📋 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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