The earliest photosynthetic microbes, before the cyanobacterial lineage developed, oxidized substances other than water. What was produced by these microbes instead of oxygen?
A) nitrate
B) elemental sulfur
C) ferrous iron
D) hydrogen sulfide

Question

Quizplus · Accepted Answer

These early photosynthetic microbes, such as purple and green sulfur bacteria, used hydrogen sulfide instead of water as an electron donor, producing elemental sulfur as a byproduct.

The Earliest Photosynthetic Microbes, Before the Cyanobacterial Lineage Developed, Oxidized