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 solve the question regarding where the photolysis of water takes place, we can break down the information step by step:

### Step 1: Understand Photolysis of Water
Photolysis of water is a process that occurs during photosynthesis where water molecules are split into oxygen, protons, and electrons using light energy. This process is crucial for the light-dependent reactions of photosynthesis.

### Step 2: Identify the Photosystems
In plants, there are two main photosystems involved in photosynthesis:
- **Photosystem I (PS1)**
- **Photosystem II (PS2)**

### Step 3: Functions of Photosystems
- **Photosystem II (PS2)**: The primary function of PS2 is the photolysis of water. It absorbs light energy, which is used to split water molecules, releasing oxygen as a by-product, protons, and electrons.
- **Photosystem I (PS1)**: The main role of PS1 is to synthesize NADPH by receiving electrons from PS2.

### Step 4: Location of Photolysis
The photolysis of water occurs in the **thylakoid membranes** of chloroplasts, specifically in the **thylakoid lumen**. This is where the light-dependent reactions take place.

### Step 5: Conclusion
Since the question asks where the photolysis of water occurs, the correct answer is:
- **Photosystem II (PS2)**

Thus, the answer to the question is **Photosystem II (PS2)**.

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