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 Can Do for You 1996 mini-calendar. In the UK charts, it reached number 84 in its first release on February 19, 1994 and then number 43 on November 11, 1995. The song deals with sexual harassment with which Sheryl says she experienced her share of during her road to fame. What I Can Do for You "What I Can Do for You" is a single by Sheryl Crow from the album "Tuesday Night Music Club" released on A&M Records. It was originally released in 1993 and the single includes a rare speedier version of LP track "The Na-Na Song" (i.e. "Volvo Cowgirl 99"). "What