Members of which bacterial phylum generated the first atmospheric oxygen on earth?

The correct answer is cyanobacteria (ancient cyanobacteria).

The huge concentration of oxygen in the atmosphere is believed to have been initially produced by the actions of ancient cyanobacteria. They are usually observed as symbionts with a number of another group of species, like coral, lichens (fungi), Azolla (pteridophytes), angiosperms, and others.

The atmosphere of oxygen was generated by various cyanobacteria at the time of Proterozoic and Archaean periods.

the calvin cycle has three stages. in stage 1, the enzyme rubisco incorporates carbon dioxide into an organic molecule. in stage 2, the organic molecule is reduced. in stage 3, rubp, the molecule that starts the cycle, is regenerated so that the cycle can continue

b is dominant over the allele for the white fur.