What is photosynthesis?

Green plants make their own sugars by the process of photosynthesis.

Microscope view of plant cells.
Microscope view of plant cells

Photosynthesis takes place inside the chloroplasts of plant cells. Chlorophyll, the green pigment found in chloroplasts, traps light energy, usually from the sun.

Plants also take in raw materials from the environment, water through their roots and carbon dioxide through the stomata of their leaves by diffusion.

Sugar is made for plants to use and oxygen is released into the atmosphere which is very useful for humans and other organisms that carry out aerobic respiration.

Overall energy conversion during photosynthesis

Energy cannot be produced or used up, it can only be converted from one form to another.

In photosynthesis, light energy is converted into chemical energy which is stored in the sugar molecules produced. This stored energy is then available to the plant cells to use.

The process of photosynthesis

The word photosynthesis can be broken down into its two parts: 'photo' meaning light and 'synthesis' meaning to make. So plants use light to make their own food (in the form of sugar).

The overall process of photosynthesis can be summarised by the word equation shown below.

A flow chart demonstrating the definition of an enzyme. 2 raw materials - carbon dioxide and water are added tofether.  Light is added along with chlorophyll and enzymes.  The result is 2 products - sugar and oxygen.

In reality photosynthesis consists of a series of chemical reactions, with each reaction being catalysed by a specific enzyme. The reactions of photosynthesis can be divided into two separate stages that take place in different locations within the chloroplast.