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 Do What I Do What I Do is the twelfth studio album by American country music artist Alan Jackson. It was released on September 7, 2004, and produced four singles for Jackson on the Hot Country Songs charts: "Too Much of a Good Thing" and "Monday Morning Church" both reached #5, while "The Talkin' Song Repair Blues" and "USA Today" both reached #18. "What I Do", however, was the first album of his career not to produce any #1 hits. The Wrights, a duo composed of Adam and Shannon Wright (the former of whom is Jackson's nephew) are featured as background