The early organisms that produced the first oxygen gas in Earth's atmosphere were
A) aerobic eukaryotes.
B) anaerobic eukaryotes.
C) photosynthetic prokaryotes.
D) aerobic prokaryotes.
E) completely unlike modern organisms.

Question

Quizplus · Accepted Answer

The early organisms that produced the first oxygen gas in Earth's atmosphere were photosynthetic prokaryotes. This is supported by the fact that the oldest rocks in the world contain evidence of photosynthetic bacteria, and that the ability to photosynthesize is found in many prokaryotic groups.

The Early Organisms That Produced the First Oxygen Gas in Earth's