A-LevelBiologyEnzymesOct/Nov 2020Paper 1 Q71 Mark
Diastase is an enzyme that breaks down starch into maltose. Maltose is a reducing sugar. A sample of starch is treated with boiled diastase and left for 15 minutes. Samples of the mixture are then tested with iodine solution and with Benedict's reagent. What are the results? [Figure 7.1]
Aiodine solution: blue-black, Benedict's reagent: blue
Biodine solution: blue-black, Benedict's reagent: red
Ciodine solution: brown, Benedict's reagent: blue
Diodine solution: brown, Benedict's reagent: red
✓ Correct Answer
The correct answer is A: iodine solution: blue-black, Benedict's reagent: blue
📋 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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