Where does the electron released from splitting water go?

Where does the electron released from splitting water go?

• A. Remains in water
• B. Used to form NADPH directly
• C. Used to build starch
• D. Passed to chlorophyll and helps form ATP

Answer: (D)

Light-driven splitting of water feeds the photosynthetic electron transport chain. The electron released right away goes to the chlorophyll in Photosystem II that lost an electron when it absorbed light. That replacement keeps photosystem II functioning and sets the electron flow in motion. As this electron travels through the chain, its movement powers proton pumping across the thylakoid membrane, creating the gradient that ATP synthase uses to make ATP. Later in the chain, the electrons help reduce NADP+ to NADPH, but the key immediate step is feeding chlorophyll and driving ATP production. So the electron is passed to chlorophyll and helps form ATP. It doesn’t stay in water, it isn’t used directly to make NADPH at that moment, and it isn’t used to build starch.

Light-driven splitting of water feeds the photosynthetic electron transport chain. The electron released right away goes to the chlorophyll in Photosystem II that lost an electron when it absorbed light. That replacement keeps photosystem II functioning and sets the electron flow in motion. As this electron travels through the chain, its movement powers proton pumping across the thylakoid membrane, creating the gradient that ATP synthase uses to make ATP. Later in the chain, the electrons help reduce NADP+ to NADPH, but the key immediate step is feeding chlorophyll and driving ATP production. So the electron is passed to chlorophyll and helps form ATP. It doesn’t stay in water, it isn’t used directly to make NADPH at that moment, and it isn’t used to build starch.