An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to
A) generate intense lightning storms.
B) change the atmosphere from oxidizing to reducing.
C) make it easier to maintain reduced molecules.
D) cause iron in ocean water and terrestrial rocks to rust (oxidize).
E) prevent the formation of an ozone layer.

Question

Quizplus · Accepted Answer

Oxygen gas would react with iron in ocean water and terrestrial rocks, causing them to rust (oxidize). This is evident by the many iron formations found in rock layers before and after the Great Oxygenation Event.

Answer: E
 The release of oxygen gas eventually led to the formation of an ozone layer, which prevented harmful UV radiation from reaching the Earth's surface. However, at the onset of oxygenation, there would have been a period of time where there was insufficient ozone to block harmful UV radiation, leading to environmental stresses on early life forms.

An Early Consequence of the Release of Oxygen Gas by Plant