A-LevelBiologyCell membranes and transportMay/June 2025Paper 1 Q191 Mark
The graph shows the results of an osmosis investigation using potato tissue. [Figure 19.1 (graph of percentage change in mass vs concentration of sodium chloride)] What is the concentration of sodium chloride solution that has the equivalent water potential to this potato tissue and what is correct about the movement of water at that point?
A0.37 mol dm⁻³ and no net movement of water
B17 mol dm⁻³ and net movement of water out of the potato tissue
C0 mol dm⁻³ and no net movement of water
D0.9 mol dm⁻³ and net movement of water into the potato tissue
✓ Correct Answer
The correct answer is A: 0.37 mol dm⁻³ and no net movement of water
📋 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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