Grass-Biotic
Table-Abiotic
Rocks-Abiotic
Butterfly-Biotic
Mushroom-Biotic
Clouds-Abiotic
Sand-Abiotic
Shark-Biotic
Trees-Biotic
Temperature-Abiotic
<u>Answer:</u>
Cyanobacteria start producing pure oxygen around 200 million years ago.
<u>Explanation:</u>
Many scientists believed that Earth did not have any oxygen. Cyanobacteria or the blue green algae are the microbes which produced oxygen for the first time with the help of photosynthesis. This was around 4.5 billion years ago: after Hadean eon.
They were very simple, but they produced oxygen in the early earth’s atmosphere. So, they brought evolution on earth. This “blue-green algae” exists in salt water, rocks and soils and play a major role in maintaining the ecosystem.
