Cyanobacteria were the first photosynthetic organisms. How were they responsible for allowing higher life forms to evolve?

They released oxygen, which mixed to form iron, and later ferrous oxide, in the air.

They released carbon dioxide, which evolving animals needed.

They released oxygen, which created the ozone layer, resulting in reduced mutation rate.

Question

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

abhisar · Answer

They were responsible for oxygen revolution. They evolved great amounts of oxygen by oxygenic photosynthesis.

abhisar · Answer

Ozone is O3, which blocks the UV rays which are highly mutagenic. Thus 3rd option is the most relevant one.