Final answer:
The statement that NADPH is the final electron carrier is false. It serves as a carrier transferring electrons to the Calvin cycle in photosynthesis. Electrons originate from water and are excited by light before being transferred to NADP+ to form NADPH.
Step-by-step explanation:
The statement saying the final electron carrier is NADPH is false. In photosynthesis, NADPH is not the final electron carrier; it is instead a carrier that transfers the high-energy electrons derived from light excitation to the Calvin cycle for carbon fixation. The primary role of NADPH in photosynthesis is as a reducing agent, donating electrons that are ultimately used to reduce carbon dioxide into glucose.
In the context of the photosynthetic electron transport chains, the external source of the electrons that ultimately pass through is water. These electrons are excited by the light energy absorbed by a light-harvesting pigment molecule and are then passed down the electron transport chain, eventually to NADP+ to form NADPH.
During the light-dependent reactions, two types of energy-carrier molecules are produced: ATP and NADPH. These molecules carry the energy necessary for the subsequent light-independent reactions (Calvin cycle), where the synthesis of sugars takes place.