How a leaf makes food
A leaf has no mouth. Yet it makes the food the whole plant lives on. That food is glucose, a sugar.
- Some leaf cells hold green dots. They are called chloroplasts.
- Carbon dioxide enters through a pore.
- Water comes up from the roots.
- Chlorophyll, the green colouring in them, catches sunlight.
- Glucose is made. Oxygen leaves.
Loading lab…
Tap each item. Is it a need, or a product?
The rule
Photosynthesis is how a green plant makes food. Some leaf cells hold green dots. These are chloroplasts. They contain chlorophyll, the green colouring that takes in sunlight.
Photosynthesis needs carbon dioxide, water, sunlight and chlorophyll. It makes glucose and oxygen. Extra glucose is stored as starch. Starch is a food that plants store.
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
| Event | What happens |
|---|---|
| Catch | Chlorophyll takes in light energy. |
| Split | Light energy is turned into chemical energy. Water breaks into hydrogen and oxygen. |
| Build | Carbon dioxide gains hydrogen and becomes sugar. This is called reduction. |
Carbon dioxide enters through tiny pores called stomata. Each pore has two guard cells. A guard cell fills with water and swells. Then the pore opens. When the cells lose water, they shrink and the pore closes. Open pores let water escape. A closed pore keeps water in.