Question

Cyanobacteria were the first photosynthetic organisms. How were they responsible for allowing higher life forms to evolve? A. They released oxygen, which mixed to form iron, and later ferrous oxide, in the air. B. They released carbon dioxide, which evolving animals needed. Or C. They released oxygen, which created the ozone layer, resulting in reduced mutation rate.

Answer 1

C - the ozone layer created by the oxygen from photosynthesis acts as a layer in the atmosphere which blocks UV radiation from the sun. Whilst some still gets through a much larger portion was blocked and so there were less mutations caused. The mutation in question is the formation of thymine dimers in DNA which causes a frame-shift mutation in the DNA where it occurs, leaving a significant change to protein structures. By stopping this organisms were much more stable and became able to develop into a more complex life form.

Answer 2

c for sure - kakitchener response was right

Answer 3

agreed, its C. kakitchener is right on the money

Answer 4

Actually,big up Kakitchener.Ur too right

Answer 5

i agree with Kakitchener...C is the best option...Photosynthetic bacteria consume CO2 and release O2, therefore B is incorrect