A-LevelBiologyCell membranes and transportFeb/Mar 2025Paper 1 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?
A0.58:1
B0.67:1
C1.50:1
D1.71:1
✓ Correct Answer
The correct answer is B: 0.67:1
📋 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.
🔒
Unlock the Examiner's Analysis
Sign up for free to reveal the full examiner report, trap analysis, and mark scheme breakdown for this question.
Sign Up Free to Unlock →Join thousands of Cambridge students already using Oracle Prep