About _______ years ago, prokaryotes probably first added adequate quantities of oxygen to the atmosphere to allow for the evolution of aerobic cellular metabolism.

Question

Quizplus · Accepted Answer

This is known as the Great Oxygenation Event and is estimated to have occurred around 2.5 billion years ago. This significant increase in atmospheric oxygen allowed for the evolution of aerobic cellular metabolism. The other options are too early (such as 3.8 and 4.6 billion years ago) or too late (such as 500 million and 1 billion years ago) to coincide with this event.

About _______ Years Ago, Prokaryotes Probably First Added Adequate Quantities