NADPH is produced in Photosystem I through a non-cyclic pathway. In this process, light energy excites electrons in Photosystem I, causing them to be transferred to a primary electron acceptor. These high-energy electrons then travel through a series of proteins in the electron transport chain, ultimately leading to the reduction of NADP+ to NADPH.
To clarify further, the term ‘cyclic’ refers to the cyclic photophosphorylation process where electrons are recycled back to the Photosystem I reaction center, primarily producing ATP, but not NADPH. Non-cyclic photophosphorylation, on the other hand, involves the linear flow of electrons that results in the production of both ATP and NADPH. Therefore, in the context of NADPH production, it clearly occurs in a non-cyclic fashion during the light reactions of photosynthesis.