What is the function of NADPH in photosynthesis?

NADPH plays a crucial role in photosynthesis as an electron carrier and donor. During the light-dependent reactions of photosynthesis, light energy is captured by chlorophyll and used to split water molecules, releasing oxygen and generating energy-rich molecules, including ATP and NADPH. The primary function of NADPH is to provide the reducing power necessary for the conversion of carbon dioxide into glucose during the light-independent reactions, also known as the Calvin cycle.

In this phase, NADPH donates electrons to the carbon compounds, facilitating the reduction reactions that ultimately lead to the synthesis of carbohydrate molecules. This contrasts sharply with other processes listed in the choices. Energy storage is more directly attributed to glucose and ATP rather than NADPH itself. Oxygen release occurs as a byproduct of water splitting in the light-dependent reactions, but it is not the function of NADPH. Water absorption is involved in photosynthesis but does not relate to NADPH's specific role. Thus, the identification of NADPH as an electron carrier/donor accurately represents its critical function in the biochemical pathways of photosynthesis.