Photosynthesis explained
The equation, where it happens and what limits its rate.
The equation
carbon dioxide + water → glucose + oxygen, using light energy. Symbols: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. It is endothermic, meaning it takes in energy.
Where it happens
In the chloroplasts of plant cells, which contain green chlorophyll that absorbs light.
Limiting factors
The rate is limited by whichever is in shortest supply: light intensity, carbon dioxide concentration or temperature (and the amount of chlorophyll).
✏️ Worked example
A plant in bright light has its CO₂ increased and the rate goes up. What was limiting it?
Carbon dioxide concentration was the limiting factor.
🧠 Test yourself
What gas is released by photosynthesis?
Oxygen.
What do plants use glucose for?
E.g. respiration, making starch, cellulose and proteins.
Is photosynthesis exothermic or endothermic?
Endothermic.
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