EVERYDAY SCIENCE

Detailed explanation-1: -Cyanobacteria produced the oxygen that began to accumulate on Earth 2.5 billion years ago, at the dawn of the Proterozoic Eon. By 2.4 billion years ago, the Great Oxidation Event (GOE) marked the onset of an atmosphere containing oxygen.

Detailed explanation-2: -That changed with the Great Oxygenation Event (GOE), a period that scientists believe marked the beginning of oxygen’s permanent presence in the atmosphere. Previous estimates have placed the start of the GOE at around 2.3 billion years ago, though with uncertainties of tens to hundreds of millions of years.

Detailed explanation-3: -Earth’s oxygen supply originated with cyanobacteria, tiny water-dwelling organisms that survive by photosynthesis. In that process, the bacteria convert carbon dioxide and water into organic carbon and free oxygen.

Detailed explanation-4: -These microbes possessed the remarkable ability to perform photosynthesis, (i.e., they could generate energy from sunlight). Cyanobacteria possessed the machinery to utilize water as a fuel source by oxidizing it. More significantly, the by-product of photosynthesis happened to be oxygen.

Detailed explanation-5: -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.