Question

Oxygen was initially created in Earth's atmosphere by _____.

Answer 1

Which would also be known as cyanobacteria photosynthesizing. Good Luck!

Answer 2

Oxygen was initially created in Earth's atmosphere by algaes. It is estimated that marine plants produce between 70 and 80 percent of the oxygen in the atmosphere. Nearly all marine plants are single celled, photosynthetic algae. Hope this answers the question.