Z-scheme of noncyclic photophosphorylation

Left - diagram of the Z-scheme of noncyclic photophosporylation (click to enlarge).

A photon is absorbed by Photosystem II and the two resultant excited electrons are passed to Photosystem I, which employs a second photon to further boost their energy for the overall reaction: NADP+ + H+ + 2e- → NADPH