What process produces NADPH in addition to ATP and requires the presence of water?

The process that produces NADPH in addition to ATP and requires the presence of water is indeed non-cyclic photophosphorylation. This process occurs during the light-dependent reactions of photosynthesis in the thylakoid membranes of chloroplasts.

In non-cyclic photophosphorylation, chlorophyll absorbs light energy, which is then used to excite electrons. Those excited electrons are transferred through a series of proteins in the electron transport chain. As these electrons move, they help to pump protons into the thylakoid lumen, creating a proton gradient that ultimately drives ATP synthesis.

Additionally, water molecules are split in a process known as photolysis, providing both electrons and protons while releasing oxygen as a byproduct. The electrons that are derived from the splitting of water replace those lost by chlorophyll. Importantly, some of these excited electrons are used to reduce NADP+ to form NADPH, which is then utilized in the Calvin cycle for the fixation of carbon dioxide into organic molecules.

In contrast, cyclic photophosphorylation only produces ATP and does not involve the splitting of water or the production of NADPH. The Calvin cycle operates using ATP and NADPH produced in the light-dependent reactions but does not perform the