The Calvin cycle isn't photosynthesis, it's known as the "dark reactions" because it can occur in the absence of light.
The electrons in P680 are passed along to Pheophytin, a small molecule that is in the thylakoid membrane of the chloroplast. These electrons then are passed to plastoquinone (another small molecule in the membrane), reducing it. (It takes protons from the outside and will eject them on the inside, creating a proton gradient.) Plastoquinone passes the electrons to cytochrome b6f, which is a protein stuck in the thylakoid membrane. Cytochrome b6f passes the electrons to plastocyanin, which is a protein on the inside of the thylakoid. Plastocyanin passes the electrons to P700 molecules in photo system I, which is also accepting light. P700 will pass electrons to ferredoxin, which will be used by NADP reductase to produce NADPH. By the way, when H2O
O2, protons are put inside the thylakoid. The proton gradient from that and from plastoquinone is used to make ATP.
In short, the stuff that's in your textbook is describing the transfer of electrons. We need all those steps to physically separate photosystem I and photosystem II. If photosystem I and photosystem II were right next to each other, we wouldn't be able to produce NADPH, only ATP. Although I can't really explain why anymore, it's been two years since I took the class that I learned this in.
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