Question

how was o2 form in atmosphere

Answer 1

These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen. In fact, all the plants on Earth incorporate symbiotic cyanobacteria (known as chloroplasts) to do their photosynthesis for them down to this day.

Answer 2

Early Bacterial life introduced oxygen to the atmosphere. As the first free oxygen was released through photosynthesis by Cyanobacteria, it was initially soaked up by iron dissolved in the ocean and formed red Coloured iron Oxide, which settled to the ocean Floor.



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