Photosynthesis

Photosynthesis is the chemical change which happens in the leaves of green plants. It is the first step towards making food, not just for plants but ultimately every animal on the planet as well. During this reaction, carbon dioxide and water are converted into glucose and oxygen. The reaction requires light energy, which is absorbed by a green substance called chlorophyll.

Photosynthesis takes place in leaf cells. These contain chloroplasts - tiny objects that contain chlorophyll.

Here are the equations for photosynthesis:

Higher tier only for the following equation

Products of photosynthesis

Glucose is soluble. It is transported in the plant as soluble sugars but stored as starch - which is insoluble, so it cannot escape from the cells. The stored starch can be turned back into glucose later and used to release energy by respiration. Starch and glucose can also be used by the plant to make:

• cellulose for their cell walls
• proteins for growth and repair
• fats and oils for storage by the plant