A-LevelBiologyCell membranes and transportFeb/Mar 2021Paper 1 Q171 Mark
When living pancreatic cells were placed in a solution of a red stain called neutral red, the cytoplasm became red. The cells were then removed from the solution of neutral red. The red stain in the cytoplasm moved into vesicles, which were exported from the cell, eventually leaving the cell colourless. Which transport mechanisms could explain how the red stain entered and left the cells?
Aactive transport and facilitated diffusion
Bdiffusion and exocytosis
Cfacilitated diffusion and endocytosis
Dosmosis and exocytosis
✓ Correct Answer
The correct answer is B: diffusion and exocytosis
📋 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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