Production of Oxygen by Photosynthesis
- Primitive plants and algae began photosynthesising which used up carbon dioxide from the atmosphere and released oxygen:
Carbon dioxide and water producing glucose and oxygen during photosynthesis
- The balanced symbol equation for photosynthesis is:
Balanced symbol equation for photosynthesis
- Through these processes over a long period of time, the amount of O2 in the atmosphere increased and the amount of CO2 decreased
- Algae first evolved around 2.7 billion years ago and during the next billion years or so small green plants began to appear
- As more and more plants began to appear the levels of oxygen began to increase which allowed for more complex life forms to evolve
- This trend continued until around 200 million years ago the composition of the atmosphere reached similar characteristics as today: around 20% oxygen, 80% nitrogen and tiny amounts of other gases
- Marine algae are throught to be responsible for about 90% of all the atmospheric oxygen produced
