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A-LevelBiologyBiological moleculesFeb/Mar 2020Paper 3 Q218 Marks

Starch grains from different types of plant differ in size and shape. Some starch grains have rings on their surfaces. You will now observe and draw starch grains from one type of plant. 1. Put one clean and dry microscope slide onto a paper towel. 2. Using a pipette, put a few drops of S onto the slide. S is a suspension of starch grains. 3. Cover the drops of S on the slide with a coverslip and use a paper towel to remove any excess suspension. 4. Use the microscope to find and observe the starch grains on the slide. You may need to reduce the amount of light entering the microscope and adjust the fine focus to observe the starch grains clearly. 5. Select, from a single field of view, four starch grains that show different sizes and features.

📋 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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About This A-Level Biology Question

Topic

This structured question tests Biological molecules in A-Level Biology (syllabus code 9700). It is worth 18 marks.

Source

This question appeared in the Cambridge A-Level Biology Feb/Mar 2020 examination, Paper 3 Variant 3.

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