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