Question

Scientists think that oxygen produced by the first photosynthetic bacteria contributed to the creation of the ozone layer we have today. If the ozone layer blocked visible instead of UV radiant energy, what do you think would have happened to life on early Earth?

Life on Earth would have evolved more quickly due to mutations in the DNA of early cells.

The photosynthetic bacteria would have lost the radiant energy source they use to make chemical energy and would have died out.

The photosynthetic bacteria would have turned to aerobic respiration for chemical energy production.

Answer 1

Or photosynthetic bacteria on land would have depended on the higher energy UV light to make chemical energy instead.

Answer 2

@radar @karatechopper

Answer 3

1 and 3 are totally false. 2 and 4 are very probable but I am leaning towards 2.

Answer 4

A is wrong as when bacteria are exposed to high doses of UV radiation they enter into SOS DNA repair and (basically) die.
B. is what I am leaning towards.
C. is false as they need oxygen to do aerobic respiration and they wouldn't produce the oxygen
D. Is wrong... Just... Wrong.

Answer 5

I say 2 because photosynthesis relies on light not UV. So without light there is not growth. With four it is possible that they could have evolved to use UV radiation rather then light but it is something that would likely not happen.

Answer 6

Probably, there wouldn't be any photosynthetic bacterias in the first place, if visible light were blocked off from entering the earth.

Answer 7

option 2 is right .. but when they are deprived of light energy there might chance of organism mutating itself to use UV source to synthesize chemical energy.