Summarise the process of photosynthesis.

Photosynthesis is a process used by plants, algae, and certain bacteria to convert light energy, usually from the sun, into chemical energy in the form of glucose (or sugar). Here are the steps involved:

1. Absorption of Light: The process begins when the chlorophyll in the chloroplasts of the plant cells absorbs sunlight. This light energy is used to excite electrons to a higher energy state.

2. Water Splitting: The excited electrons cause water molecules to split in a process called photolysis. This splitting of water molecules releases oxygen gas and hydrogen ions. The oxygen is released into the atmosphere, and the hydrogen ions are used in the next step.

3. Carbon Dioxide Fixation: The hydrogen ions combine with carbon dioxide (taken from the atmosphere) in a series of reactions known as the Calvin cycle. This process converts the carbon dioxide and hydrogen into glucose.

4. Release of Oxygen: The oxygen produced during photolysis is released into the atmosphere as a by-product of photosynthesis.

5. Formation of Glucose: The glucose produced is used by the plant for growth and energy. Some of it is also converted into other substances like cellulose and starch, which are stored for later use.

In summary, photosynthesis is a process that converts light energy into chemical energy, producing oxygen and glucose in the process. This process is vital for life on Earth as it is the primary source of oxygen in the atmosphere, and it forms the basis of the food chain.