Question

Which of the following was most likely responsible for the fact that organic molecules no longer form spontaneously on Earth? The amount of UV radiation increased. The amount of oxygen in the atmosphere increased. Water accumulated in the oceans. Earth's surface temperature warmed.

Answer 1

The amount of oxygen in the atmosphere increased:)

Step-by-step explanation:

Answer 2

The amount of oxygen in the atmosphere increased.

Step-by-step explanation:

Spontaneous formation of organic molecules occurred on primitive earth since its atmosphere did not have oxygen. The reducing atmosphere allowed chemogenesis. Evolution of photosynthesizing organisms that use water as a source of electron led to the accumulation of oxygen in the atmosphere. Presence of oxygen does not allow the spontaneous formation of organic molecules since the molecules are readily oxidized.