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andrew11 [14]
3 years ago
13

The oxygen build-up in the atmosphere was caused by .

Biology
2 answers:
Ymorist [56]3 years ago
6 0

<em>Eukaryotic Organisms</em>

vladimir1956 [14]3 years ago
3 0
Most scientists believe that for half of Earth's 4.6-billion-year history, the atmosphere<span>contained almost no </span>oxygen. Cyanobacteria or blue-green algae became the first microbes to produce oxygen<span> by photosynthesis, perhaps as long ago as 3.5 billion years ago and certainly by 2.7 billion years ago.
this answer came from this website </span>The Rise of Oxygen - Astrobiology Magazine<span>www.astrobio.net/news-exclusive/the-rise-of-oxygen/
it should help</span>
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