The photosystem I can function itself if the phosphorylation occurs by the cyclic movement of electrons, such a process is termed as cyclic photophosphorylation. The excited electrons get cycled back in the cyclic photophosphorylation. The electrons will not pass to NADP+ so the formation of NADPH+ H+ does not occur in the cyclic photophosphorylation. In this photophosphorylation the photolysis of water, formation of NADPH and oxygen does not take place.
