Early organisms were anaerobic. As early organisms evolved the ability to harness energy from the sun, other organisms began to die out because they were ____.
A) destroyed by a meteorite
B) outcompeted by multicelled organisms
C) consumed by dinosaurs
D) poisoned by oxygen gas
E) starved

Question

Quizplus · Accepted Answer

As early organisms evolved the ability to harness energy from the sun through photosynthesis, they began producing oxygen as a byproduct. This increase in atmospheric oxygen was toxic to the existing anaerobic organisms, leading to what is known as the Great Oxygenation Event.

Early Organisms Were Anaerobic