Which of the following organisms was the first to introduce oxygen into Earth's atmosphere?
A)cyanobacteria
B)early protozoans
C)plants
D)green algae

Question

Quizplus · Accepted Answer

Cyanobacteria, also known as blue-green algae, are believed to be the first organisms to produce oxygen via photosynthesis around 2.5 billion years ago. This process dramatically changed the Earth's atmosphere and paved the way for the evolution of oxygen-dependent life forms. Early protozoans and green algae also played a role in the oxygenation of the atmosphere, but cyanobacteria were the first. Plants evolved much later, around 500 million years ago, and played a significant role in increasing oxygen levels in the atmosphere.

Which of the Following Organisms Was the First to Introduce