Describe how the products of photosynthesis are used by a plant, and explain why photosynthesis is essential for the plant's survival.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Plants are the primary producers in most ecosystems. They use photosynthesis to convert light energy into chemical energy stored in glucose. Without photosynthesis, plants could not grow, reproduce, or respond to their environment.
Model answer (5 marks)
1. Glucose is oxidised in cellular respiration to release ATP, which powers the plant’s life processes.
2. Excess glucose is polymerised into starch and stored in chloroplasts, roots or seeds for later use.
3. Glucose is a precursor for cellulose synthesis, forming the structural component of cell walls.
4. Glucose reacts with nitrate ions taken up from the soil to form amino acids, which are then polymerised into proteins.
5. Without photosynthesis the plant cannot produce glucose or other organic molecules, so it cannot grow, respire or build biomass, leading to death.
2. Excess glucose is polymerised into starch and stored in chloroplasts, roots or seeds for later use.
3. Glucose is a precursor for cellulose synthesis, forming the structural component of cell walls.
4. Glucose reacts with nitrate ions taken up from the soil to form amino acids, which are then polymerised into proteins.
5. Without photosynthesis the plant cannot produce glucose or other organic molecules, so it cannot grow, respire or build biomass, leading to death.
Examiner tips
- Use the exact terms (respiration, starch, cellulose, amino acids, proteins).
- Show the flow from glucose to each product. 5 points are awarded for covering all five items.
Mark scheme (5 marks)
- Glucose is used in respiration to release energy for the plant's life processes
- Glucose is converted into starch for storage
- Glucose is used to make cellulose for cell walls
- Glucose combined with nitrate ions (from the soil) to make amino acids / proteins
- Without photosynthesis the plant cannot make glucose / organic molecules, so it cannot grow, respire or produce biomass
Key terms in this question
Related
- All Edexcel A-Level Biology A: Salters-Nuffield (9BN0) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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