Chapter 4

Photosynthesis

See how green plants use sunlight, water and air to make their own food!

How plants make food

Plants are amazing! Unlike animals, they can make their own food. This food-making process is called photosynthesis. It happens mostly in the green leaves.

To make food, a plant needs four things: sunlight, water, carbon dioxide and a green colour called chlorophyll. Chlorophyll is found in the leaves and traps the energy in sunlight.

Key idea

sunlight + water + carbon dioxide → food (sugar) + oxygen. This only happens in green plants.

Where each part comes from

  • Roots soak up water from the soil.
  • Leaves take in carbon dioxide from the air.
  • Leaves catch sunlight using chlorophyll.

The plant turns these into sugar, which is its food. It also gives out oxygen, the gas we need to breathe.

Example

On a sunny day, a leafy tree makes lots of food and lets out oxygen. That is why forests help keep our air fresh.

Remember

  • Photosynthesis happens in the day, when there is light.
  • It gives out oxygen for animals and people.

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