Microorganisms Were Probably Restricted to the Oceans and Subsurface Environments

Question

Microorganisms were probably restricted to the oceans and subsurface environments until
A) aquatic life brought them onto land.
B) chemoorganotrophy developed.
C) phototrophy evolved.
D) the ozone layer was made.

Accepted Answer

The ozone layer, which protects living organisms from harmful ultraviolet (UV) radiation, had to form before microorganisms could safely inhabit terrestrial environments. The presence of the ozone layer made it possible for life to move from the protective waters and subsurface areas to land, as it shielded them from UV radiation that could damage or kill them.