Hi, i'm having trouble on understand the Photosystems as my book is not really clear about it. It says that in the non-cyclic photophosphorylation electrons are released from photosystem II and are released then the electrons are accepted by the primary electron acceptor then by plastoquinone then cytochrome b6f complex then plastocyanin and then to photosystem I. In photosystem I the high energy electron is ejected and passes onto electron acceptor ferredoxin and then NADP+ reductase and the NADP+ reductase makes NADPH and release it to the stroma. Then it says in the cyclic photophosphorylation, electron are released from the photosystem I and the electron are passed on to an electron acceptor called FeS. FeS then passes the electron to ferredoxin. I'm confused, aren't FeS ferredoxin? and it also says that in cytochrome b6f complex, the flow of electrons provides energy to pump H+ across the thylakoid membrane. What does this means? Thank you.