Photosynthesis
Plants convert light, water and CO₂ into glucose and oxygen.
About this topic
Photosynthesis is the process in which plants, algae and some bacteria use light energy to make glucose from carbon dioxide and water, releasing oxygen: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. It occurs in chloroplasts, where chlorophyll absorbs mainly red and blue light.
It has two stages: light-dependent reactions in the thylakoids and the Calvin cycle in the stroma. Photosynthesis supplies the food and oxygen for nearly all life, and is the origin of fossil fuels.
A simple experiment shows it: a water plant under a lamp releases bubbles of oxygen, and more bubbles appear if the lamp is moved closer. Plants take carbon dioxide from the air through stomata, water from the soil through roots, and use light absorbed by chlorophyll to build glucose, which is used for respiration, converted to starch for storage or cellulose for walls.
Photosynthesis produced the oxygen in our atmosphere and is the base of nearly every food chain, and it also removes carbon dioxide, which is why forests matter for climate. Students often think plants get their mass from the soil; in reality most of it comes from carbon dioxide in the air. Another error is saying plants respire only at night; they respire day and night but photosynthesise only in light.
Key ideas
- 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
- Occurs in chloroplasts
- Chlorophyll absorbs light
Quick check
Use cases: where Photosynthesis helps
- Homework: review the key idea behind Photosynthesis before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Photosynthesis without notes.
- Visual learning: play with the interactive lab to see how Photosynthesis changes when you adjust its inputs.
- Teaching a friend: explain Photosynthesis in your own words, then compare your version with the key ideas.
Biology underpins medicine, farming, conservation and biotechnology.
Frequently asked questions
What is Photosynthesis?
Plants convert light, water and CO₂ into glucose and oxygen.
What will I learn in Photosynthesis?
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Occurs in chloroplasts. Chlorophyll absorbs light.
Is Photosynthesis part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Photosynthesis lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Photosynthesis?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.