Photosynthesis More recent studies, reported in March 2018, also suggest that photosynthesis may have begun about 3.4 billion years ago. The main source of oxygen in the Earth's atmosphere derives from oxygenic photosynthesis, and its first appearance is sometimes referred to as the oxygen catastrophe. Geological evidence suggests that oxygenic photosynthesis, such as that in cyanobacteria, became important during the Paleoproterozoic era around 2 billion years ago. Modern photosynthesis in plants and most photosynthetic prokaryotes is oxygenic. Oxygenic photosynthesis uses water as an electron donor, which is oxidized to molecular oxygen () in the photosynthetic reaction center. Several groups of animals
What I Need to Do around" and go back to his lover, then hold her, and then tell her how sorry he is for what he did. What I Need to Do "What I Need To Do" is a song written by Tom Damphier and Bill Luther, and recorded by American country music artist Kenny Chesney. It was released in January 2000 as the fourth and final single from Chesney's 1999 album "Everywhere We Go". The song peaked at number 8 in the United States and number 13 in Canada in 2000. The song describes the narrator thinking about "what [he] need[s] to do" as