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

Question

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

Quizplus · Accepted Answer

The presence of oxygen in the atmosphere would have prevented the emergence of life on Earth because oxygen reacts with and destroys organic molecules, which are the building blocks of life. The first life forms on Earth likely emerged in an oxygen-free environment. Therefore, if the ancient atmosphere had the same amount of oxygen as present, life would not have emerged.

Life Probably Would Never Have Emerged on Earth If the Ancient