In electron transport chain of photosynthesis when `P_(680)` absorbs light its electrons are transferred to an electron acceptor molecule and it becomes a

Options

A. strong reducing agent and splits a molecule of water
B. strong oxidising agent and splits a molecule of water
C. weak oxidising agent and splits a molecule of ATP
D. strong oxidising agent and splits a molecule of `CO_(2)`

Answer

To answer the question regarding what happens when P680 absorbs light in the electron transport chain of photosynthesis, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding P680**: P680 is a chlorophyll molecule located in the photosystem II (PSII) of the thylakoid membrane in chloroplasts. It is called P680 because it absorbs light most efficiently at a wavelength of 680 nm.

2. **Absorption of Light**: When P680 absorbs light energy, it becomes excited. This excitation causes it to lose an electron, which is transferred to an electron acceptor molecule.

3. **Formation of P680+**: After losing an electron, P680 becomes positively charged and is referred to as P680+. This state indicates that it has been oxidized because it has lost an electron.

4. **Electron Replacement**: To replace the lost electron, P680+ must receive an electron from another source. In the context of photosynthesis, this source is water (H2O).

5. **Splitting of Water**: The process of replacing the lost electron involves the splitting of water molecules (photolysis). This reaction produces oxygen (O2), protons (H+), and electrons (e-). The reaction can be summarized as:
\[ 2H_2O \rightarrow 4H^+ + 4e^- + O_2 \]

6. **Role of Water**: The electrons released from the splitting of water are used to reduce P680+ back to P680, allowing the electron transport chain to continue functioning.

7. **Conclusion**: Therefore, when P680 absorbs light and loses an electron, it becomes P680+, which is a strong oxidizing agent that facilitates the splitting of water molecules.

### Final Answer:
When P680 absorbs light, it loses an electron and becomes P680+, a strong oxidizing agent that splits water molecules.

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