Here's why:
* Light-dependent reactions: In the light-dependent reactions, light energy is used to excite electrons in chlorophyll. These energized electrons travel through an electron transport chain, ultimately reducing NADP+ to NADPH.
* Light-independent reactions (Calvin cycle): NADPH is then used as a reducing agent in the Calvin cycle, where carbon dioxide is converted into glucose. This process requires the electrons from NADPH to add hydrogen atoms to carbon dioxide.
So, the final electron acceptor in photosynthesis is NADP+, which is reduced to NADPH and serves as the electron carrier for the Calvin cycle.
