Question

In the reaction centers in photosystem II, low-energy electrons are taken from water and high energy-electrons are given to plastiquinone in a process involving?

1) Photosynthesis
2) Cellular respiration
3) Electron transport chain
4) Glycolysis

Answer 1

Light energy is used in photosystem II to extract electrons from water during photosynthesis, passing them through the chloroplast electron transport chain and energizing them for ATP production and reduction of NADP+ to NADPH.

Step-by-step explanation:

In the photosystem II (PSII) reaction centers, light energy is harnessed to extract low-energy electrons from water. These electrons are energized and passed along to plastiquinone (Pq), which is part of the chloroplast electron transport chain. This chain, which operates during photosynthesis, is responsible for transporting the energized electrons through various carriers, including the cytochrome complex and eventually to photosystem I (PSI), where NADP+ is reduced to NADPH. Simultaneously, the splitting of water molecules adds protons to the thylakoid lumen and contributes to the formation of an electrochemical gradient across the thylakoid membrane. High-energy electrons from PSII are crucial for synthesizing ATP, as they enable ATP synthase to utilize this gradient to produce ATP, which is then used to fuel the Calvin cycle for glucose production.