A-LevelBiologyPhotosynthesisFeb/Mar 2025Paper 4 Q99 Marks
The chloroplasts of leaves of tobacco plants, Nicotiana sp., contain chlorophyll a and chlorophyll b. (a) Describe the role of chlorophyll b in photosynthesis. (b) A mutant tobacco plant was found to contain more chlorophyll b than normal tobacco plants. An investigation was carried out to measure the rate of photosynthesis of normal and mutant tobacco plants at increasing light intensities. The rate of production of oxygen was used as a measure of the rate of photosynthesis. Other variables were kept constant. [Figure 9.1] shows the results of this investigation.
📋 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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