Photosynthesis 3.5 bya
began to trap and use that energy to make food, such as . This process is called photosynthesis, meaning “constructing with light”. This was a great leap forward. Sunlight-using bacteria appeared soon after the first cells did, about 3.5 billion years ago, and sunlight has been the main source of energy for all life ever since. These bacteria are called blue-green bacteria or cyanobacteria (and sometimes wrongly called blue-green algae).
Many blue-green bacteria can also ““ atmospheric . In Southeast Asia, nitrogen-fixing blue-greens often are grown in rice paddies, removing the need for nitrogen fertilizers.
Blue-greens are important in our story for several reasons:
► they were probably the first bacteria which could perform photosynthesis, so leading to the great of 3 billion years ago
► they formed a with to create , which was probably the first living thing to live on land
Structures called stromatolites have been found from this date, and are believed to have been made by these bacteria. These still exist in Australia.
Stromatolites in Shark Bay, Australia, courtesy of Paul Harrison
How photosynthesis works
A cell uses sunlight to create sugar
As they captured sunlight energy to make sugar so carbon dioxide and water were taken in, and was given out. This oxygen had a upon the whole world.
Today we obtain almost all of our food from plants, or from animals which have eaten plants, and so it might be interesting to know a bit about how photosynthesis works. It is a fascinating story of molecular changes. We give more details in the reference section of this website.
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