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| Description: The P700 in photosystem I absorbs photons of a 700-nanometer wavelength. The P680 of photosystem II absorbs photons at 680 nanometers. Energy inputs boost P700 and P680 to an excited state in which they lose electrons. A The noncyclic pathway involves a one-way flow of electrons from water, to photosystem II, to photosystem I, to NADPH. As long as electrons continue to flow through the two electron transfer chains, H+ continues to be carried across the thylakoid membrane, and ATP and NADPH keep forming. Light provides the energy boosts that keep the pathway going. B In the cyclic pathway, electrons ejected from photosystem I are returned to it. As long as electrons continue to pass through its electron transfer chain, H+ continues to be carried across the thylakoid membrane, and ATP continues to form. Light provides the energy boost that keeps the cycle going. Picture Stats: Views: 153 Filesize: 189.87kB Height: 1053 Width: 558 Source: https://biology-forums.com/index.php?action=gallery;sa=view;id=49478 |