AP BIOLOGY

Detailed explanation-1: -The release of oxygen by cyanobacteria was thus responsible for changes in the earth’s atmospheric composition, the rise of aerobic metabolism and, ultimately, the evolution of multicellularity. Oxygen is the primary molecule that makes Earth what it is today, far more hospitable and beautiful than the early earth.

Detailed explanation-2: -Cyanobacteria, also called blue-green algae, were among the earliest organisms on Earth. These primitive bacteria produce oxygen during photosynthesis as they fix CO2 dissolved in the water.

Detailed explanation-3: -Origin. Available evidence from geobiological studies of Archean (>2500 Ma) sedimentary rocks indicates that life existed 3500 Ma. Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3.4 billion years old, consistent with recent studies of photosynthesis.

Detailed explanation-4: -And some evidence suggests cyanobacteria, the earliest photosynthetic organisms to release oxygen gas as a waste product-although not use it-may have arisen as early as 3.5 billion years ago.