A-LevelBiologyCell membranes and transportOct/Nov 2025Paper 2 Q47 Marks
Bacteria can be classified according to the type of cell wall they have. Gram-negative bacteria have a cell wall with an outer layer known as the outer membrane. Gram-positive bacteria do not have an outer membrane, but have a much thicker peptidoglycan layer than Gram-negative bacteria. Fig. 4.1 is a diagram of a section through the cell wall of a Gram-negative bacterium. [Figure 4.1]
📋 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.
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