The first oxygen evolving organisms on Earth were:
Cyanobacteria reflects key principle in quiz on section b solved pyqs, where evolutionary mechanisms shape genetic variation and adaptation. In this context, Cyanobacteria aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why Cyanobacteria fits helps integrate natural selection, environment.
Ref: Futuyma, Evolution, Drift and Speciation PYQs.