Multiple Choice
Why is there free oxygen in the air?
A) Organisms need oxygen to manufacture ATP.
B) Free oxygen has been present since the formation of the earth's atmosphere.
C) Evaporation of the oceans liberated oxygen.
D) It is a by-product of photosynthesis.
E) Free oxygen has seeped from cracks in the earth's crust.
Correct Answer:
Verified
Correct Answer:
Verified
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