What Is Photosynthesis?
Science · Life Science and Biology · Grades 3–6
Meaning at a glance
Photosynthesis is how green plants make their own food. They use light energy, water and carbon dioxide, and they release oxygen.
Also searched as: how plants make food, plants make food.
Understand it simply
Plants do not eat. They make their own food in their leaves. This is called photosynthesis.
A plant takes in light energy from the sun, water from the soil through its roots, and carbon dioxide from the air through tiny holes in its leaves. Inside the leaf, a green substance called chlorophyll captures the light. The plant makes sugar (its food) and releases oxygen into the air.
See it work
A bean seedling is growing on a sunny windowsill. Its leaves catch the sunlight. The sugar they make gives the seedling energy and the materials to grow taller. The oxygen it releases is the gas that people and animals breathe in.
Avoid this confusion
Plants do not get their food from the soil. The soil gives water and a few minerals. The food, sugar, is made in the leaves from water, carbon dioxide and light.
Chlorophyll absorbs mostly red and blue light and reflects green light, which is why leaves look green.
Try it yourself
Work these out first, then check your answers below.
Name three things a plant needs for photosynthesis.
Which gas do plants release during photosynthesis?
A plant is kept in a dark cupboard for two weeks. Why does it become weak and pale?
Check your understanding
Show the answer to question 1
Answer: Light (sunlight), water and carbon dioxide.
These are the three things a leaf uses to make sugar.
Show the answer to question 2
Answer: Oxygen
Oxygen is released into the air as the plant makes sugar.
Show the answer to question 3
Answer: It cannot photosynthesise without light.
Without light the leaves cannot make sugar, so the plant runs out of food. Chlorophyll also fades without light.
Understand more with Courseversity
You now know what photosynthesis means. Keep going with a full lesson, then explore the ideas that connect to it.
Learn
Learn this in a full lesson.
- Leaf functions (Grade 3)
- Producers (Grade 3)
- Photosynthesis introduction (Grade 5)
Practise
Practise with Learning Lab questions for the lesson Leaf functions (Grade 3), with an explanation after each answer.
Explore
Ideas that connect to this word.
- Food chain: plants are the producers at the start of food chains.
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Sources and review
- National Geographic Education: Photosynthesis – Encyclopedic entry on the inputs, outputs and chlorophyll.
Written by: Courseversity editorial team (AI-assisted draft).
Review status: checked against the sources above. Educator review is pending, so please tell us if anything looks wrong.
Last updated: 27 October 2026.