`P_(680)` is related with

Options

A. Light
B. Dark
C. Both
D. None

Answer

### Step-by-Step Solution:

1. **Understanding P680**:
- P680 is a special pair of chlorophyll a molecules found in Photosystem II (PS II) of the photosynthetic apparatus in plants.

2. **Role of Photosystems**:
- Photosystems are complexes made up of proteins and pigments that are crucial for the process of photosynthesis. They are responsible for capturing light energy.

3. **Types of Photosystems**:
- There are two types of photosystems in plants: Photosystem I (PS I) and Photosystem II (PS II).
- PS I has a special pair of chlorophyll known as P700, while PS II has P680.

4. **Light Absorption**:
- P680 absorbs light energy, which excites the electrons in the chlorophyll molecules. This excitation is essential for the photosynthetic process.

5. **Electron Donation**:
- Upon excitation, P680 donates an electron to an electron acceptor, initiating a series of reactions that ultimately lead to the conversion of light energy into chemical energy.

6. **Light-Dependent Reactions**:
- P680 is involved in the light-dependent reactions of photosynthesis, which occur in the thylakoid membranes of chloroplasts. These reactions require light to proceed.

7. **Conclusion**:
- Since P680 is directly involved in the absorption of light and the light-dependent reactions, it is related to light.

### Final Answer:
P680 is related with **light**.

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