Explain the process of photosynthesis. Draw a labelled diagram of a chloroplast.

1. 1 · Define in one line. Photosynthesis is the process by which green plants make glucose from CO₂ and water using light energy, in the presence of chlorophyll, releasing oxygen.
2. 2 · Write the equation. 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O (light, chlorophyll).
3. 3 · Draw the chloroplast. [Oval with a double membrane; grana, thylakoid, stroma lamellae, stroma, DNA, ribosomes]
4. 4 · Light reaction.
   • In the grana; chlorophyll absorbs light.
   • Photolysis: 2H₂O → 4H⁺ + 4e⁻ + O₂; oxygen is released.
   • ATP and NADPH₂ are formed.
5. 5 · Dark reaction.
   • In the stroma; the Calvin cycle; does not need light directly.
   • ATP and NADPH₂ from the light reaction are used to fix CO₂ into glucose.
6. 6 · Factors. External: light, CO₂, temperature, water, minerals. Internal: pigments, leaf age, sugar build-up, hormones.
7. 7 · Real life. All our food grains and the oxygen we breathe come from photosynthesis.
8. 8 · Close in one line. So light energy becomes chemical energy stored in glucose.

Scoring tip: Write the equation and both phases with their sites. The labelled chloroplast carries about 2 marks.