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A-LevelBiologyCell membranes and transportOct/Nov 2024Paper 1 Q161 Mark

In an experiment, pieces of onion epidermis are put into three different concentrations of sucrose solutions, P, Q and R. The pieces of onion are left for an hour and then examined using the low power of a light microscope. Each diagram shows one cell from the epidermis that was placed in each of the sucrose concentrations. What explains the appearance of cells in solution Q?

AThe concentration of solution Q is equal to the concentration of the solutes in the cell sap.
BThe cytoplasm has the same concentration of sucrose as solution Q.
CThe water potential of the cytoplasm is equal to the water potential of the vacuole.
DThe water potential of the cell sap is equal to the water potential of solution Q.

✓ Correct Answer

The correct answer is D: The water potential of the cell sap is equal to the water potential of solution Q.

📋 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 multiple-choice question tests Cell membranes and transport in A-Level Biology (syllabus code 9700). It is worth 1 mark.

Source

This question appeared in the Cambridge A-Level Biology Oct/Nov 2024 examination, Paper 1 Variant 2.

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