In non-cyclic photophosphorylation light energy absorbed by the reaction centre of Photosystem II is used in taking electrons to a

Options

A. Higher energy level, which are then replaced by electrons drawn from water molecules
B. Lower energy level, which are then replaced by electrons drawn from water molecules
C. Higher energy level, which are then replaced by electrons drawn from PSI
D. Lower energy level, which are then replaced by electrons drawn from PSI

Answer

**Step-by-Step Solution:**

1. **Understanding Non-Cyclic Photophosphorylation**: Non-cyclic photophosphorylation is a process that occurs in the thylakoid membranes of chloroplasts during photosynthesis. It involves the transfer of electrons through a series of proteins and molecules.

2. **Role of Photosystem II**: In this process, Photosystem II (PSII) plays a crucial role. The reaction center of PSII is known as P680, which absorbs light energy.

3. **Absorption of Light Energy**: When light energy is absorbed by P680, it excites electrons, raising them to a higher energy state. This is the initial step where light energy is converted into chemical energy.

4. **Electron Transfer**: The excited electrons are then transferred to a primary electron acceptor. In this case, the electrons move to a molecule called plastoquinone (PQ), which is part of the electron transport chain.

5. **Replacement of Electrons**: The electrons that were lost from P680 need to be replaced. This is done by splitting water molecules (H2O) in a process called photolysis. The reaction produces oxygen (O2) and provides new electrons to P680.

6. **Continuation of the Electron Transport Chain**: After being transferred to plastoquinone, the electrons continue to move through the electron transport chain, ultimately leading to the production of ATP and NADPH, which are essential for the Calvin cycle.

7. **Conclusion**: Thus, in non-cyclic photophosphorylation, the light energy absorbed by the reaction center of Photosystem II (P680) is used to take electrons to the primary electron acceptor, replacing the electrons lost from P680 by splitting water molecules.

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