A-LevelBiologyCell membranes and transport9700/12 · Feb/Mar 2025 · Q161 Mark

The diagram shows the dimensions of two blocks of agar. The diagram has been drawn to scale. [Figure 16.1] The blocks of agar were stained pink with a pH indicator. In acidic conditions, the pink pH indicator becomes colourless. The two blocks of agar were placed in a beaker of acid at the same time. As the acid diffused into the blocks, the blocks became colourless. What is the surface area to volume ratio of the block that became completely colourless first?

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A0.58:1

B0.67:1

C1.50:1

D1.71:1

✓ Correct answer

B: 0.67:1

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Topic: Cell membranes and transport, A-Level Biology (syllabus 9700). Multiple choice, 1 mark.
Source: A-Level Biology, Feb/Mar 2025 Paper 1 Variant 2, question 16.

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