In which of the following photolysis of water takes place ?

Options

A. PS I
B. PS II
C. Both PS I and PS II
D. Occurs in stroma of chloroplast

Answer

To determine where the photolysis of water takes place, we need to understand the process involved in photosynthesis, specifically in the light-dependent reactions.

### Step-by-Step Solution:

1. **Understanding Photolysis**:
- Photolysis refers to the process in which water molecules are split into hydrogen and oxygen atoms using light energy. This process is essential in photosynthesis, particularly in the light-dependent reactions.

2. **Identifying Photosystems**:
- In plants, photosynthesis occurs in two main photosystems: Photosystem I (PSI) and Photosystem II (PSII). Each photosystem has different roles and components.

3. **Role of Manganese**:
- Manganese (Mn²⁺) is a crucial element involved in the photolysis of water. It acts as a cofactor in the oxygen-evolving complex of Photosystem II.

4. **Location of Photolysis**:
- Photolysis of water occurs in Photosystem II. This is where the splitting of water molecules takes place, releasing oxygen as a byproduct. Photosystem II operates at a wavelength of 680 nm, which is optimal for the absorption of light required for this reaction.

5. **Conclusion**:
- Since manganese is present in Photosystem II and is essential for the photolysis of water, we conclude that the correct answer to the question is **Photosystem II**.

### Final Answer:
Photolysis of water takes place in **Photosystem II**.

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