Photosynthesis called P680. The source of electrons for photosynthesis in green plants and cyanobacteria is water. Two water molecules are oxidized by four successive charge-separation reactions by photosystem II to yield a molecule of diatomic oxygen and four hydrogen ions. The electrons yielded are transferred to a redox-active tyrosine residue that then reduces the oxidized P680. This resets the ability of P680 to absorb another photon and release another photo-dissociated electron. The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions and a calcium ion; this oxygen-evolving complex binds two water molecules and
What You Need from Me of the album. "What You Need from Me" was later released as the second track on the CD single of "This Is Gonna Hurt" on 16 August 2013. "What You Need From Me" received mixed reviews from music critics. Norbert Schiegel of "G+J Entertainment Media" described the song as "sensational," and Dirk Neuhaus of "Country Rock Magazine" called it a "fantastic track," while Adam Carroll from "Seen It Heard It" thought that the song was one of the weakest tracks from "Rocks and Honey", describing Tyler's voice as "rough and beaten" and that her and Vince Gill's voices do not