The evolution of organisms that use oxygen in their respiration was possible only because of the action of a group of bacteria that produced oxygen and changed the Earth's atmosphere from an anoxic one to one rich in oxygen.That group of bacteria was:
A)cyanobacteria
B)spirochaetes
C)proteobacteria
D)Staphylococcus
E)actinobacteria

Question

Quizplus · Accepted Answer

Cyanobacteria are the only group of bacteria known to have produced oxygen through photosynthesis, which made the atmosphere rich in oxygen and allowed for the evolution of organisms that use oxygen in their respiration. The other options listed are not known to have played a significant role in the evolution of oxygen-using organisms.

The Evolution of Organisms That Use Oxygen in Their Respiration