Life probably would never have emerged on Earth if the ancient atmosphere had been the same as the present one in regard to
A) carbon dioxide.
B) hydrogen.
C) oxygen.
D) nitrogen.
E) carbon monoxide.

Question

Quizplus · Accepted Answer

The presence of oxygen (option C) in the present atmosphere would have prevented the emergence of life on Earth. Oxygen is highly reactive and would have destroyed organic molecules necessary for the origin of life. Therefore, the ancient atmosphere must have been devoid of oxygen or had very little oxygen compared to today's atmosphere. Carbon dioxide (option A), hydrogen (option B), nitrogen (option D), and carbon monoxide (option E) were all present in the early atmosphere and could have played important roles in the origin of life.

Life Probably Would Never Have Emerged on Earth If the Ancient