A-LevelBiologyEnzymesMay/June 2019Paper 1 Q101 Mark
A fixed volume of the enzyme catalase was added to a fixed volume of hydrogen peroxide solution. The diagram shows how the concentration of product changed over the course of the reaction. [Figure: Graph showing concentration of product vs time] What explains the shape of this graph?
AThe active sites become saturated.
BThe enzyme was denatured.
CThe hydrogen peroxide inhibited the reaction.
DThe substrate molecules were used up.
✓ Correct Answer
The correct answer is D: The substrate molecules were used up.
📋 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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