How to Revise Photosynthesis — OCR A-Level Biology
Photosynthesis is a topic in the OCR A-Level Biology specification. This guide covers learning objectives, examiner tips, common mistakes, and key terminology to help you revise effectively.
Examiner Tips for Photosynthesis
- Be prepared to interpret graphs showing the effect of limiting factors on the rate of photosynthesis
- Ensure you can link the Calvin cycle intermediates (GP, RuBP, TP) to the changes in their concentrations when a limiting factor is altered
- Use precise terminology when describing the role of RuBisCO and the regeneration of RuBP
- Practice calculating rates of photosynthesis from experimental data provided in graphs
Common Mistakes in Photosynthesis
- Confusing the products of the light-dependent stage with the reactants of the light-independent stage
- Failing to correctly identify the specific site of each stage within the chloroplast
- Misinterpreting the effect of limiting factors on the concentrations of Calvin cycle intermediates (GP, RuBP, TP)
- Confusing cyclic and non-cyclic photophosphorylation mechanisms
Key Marking Points
- Interrelationship between photosynthesis and respiration regarding raw materials and products
- Structure of the chloroplast (outer membrane, lamellae, grana, thylakoid, stroma, DNA)
- Role of photosynthetic pigments in light harvesting systems and photosystems
- Light-dependent stage: production of ATP and reduced NADP via electron carriers, cyclic and non-cyclic photophosphorylation, and the role of water
- Light-independent stage (Calvin cycle): fixation of CO2, role of RuBP, RuBisCO, and GP to produce triose phosphate (TP)
- Uses of triose phosphate for synthesis of carbohydrates, lipids, and amino acids, and regeneration of RuBP