In non-cyclic photophosphorylation electrons from `P_(680 )` enter electron transport chain and are passed to

Options

A. A lower energy level, that is, the reaction centre, `P_(700)` of Photosystem I.
B. A higher energy level, that is, the reaction centre, `P_(700)` of Photosystem I.
C. A lower energy level to water
D. A higher energy level, that is, the `NADP^(+)`

Answer

**Step-by-Step Solution:**

1. **Understanding Non-Cyclic Photophosphorylation**: Non-cyclic photophosphorylation is a process that occurs in the light-dependent reactions of photosynthesis. It involves the transfer of electrons through a series of proteins embedded in the thylakoid membrane.

2. **Electrons from P680**: In this process, the reaction center of Photosystem II (PSII) contains chlorophyll a, which is designated as P680. When light is absorbed by P680, it gets excited and releases electrons.

3. **Electron Transport Chain**: The electrons released from P680 are passed to a primary electron acceptor, which is Pheophytin. This initiates the electron transport chain.

4. **Transfer of Electrons**: After being accepted by Pheophytin, the electrons are then transferred to Plastoquinone (PQ). This transfer continues through various components of the electron transport chain.

5. **Final Destination of Electrons**: Eventually, the electrons are passed to Photosystem I (PSI), specifically to the reaction center P700. This is where the electrons are re-energized by light absorption again.

6. **Energy Levels**: It is important to note that the electrons move from a higher energy level (P680) to a lower energy level (P700). The overall flow of electrons is from P680 to P700, and then they are ultimately transferred to NADP+, which is the final electron acceptor in the process.

**Final Answer**: In non-cyclic photophosphorylation, electrons from P680 enter the electron transport chain and are passed to Pheophytin, then to Plastoquinone, and finally to P700 in Photosystem I.

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