In which of the following only Ps I is found ?

Options

A. Stroma
B. Granal thylakoids
C. Stromal lamella
D. Matrix

Answer

To solve the question "In which of the following only PS I is found?", we need to understand the locations of Photosystem I (PS I) and Photosystem II (PS II) in the chloroplasts during the light reactions of photosynthesis.

### Step-by-Step Solution:

1. **Understanding Photosystems**:
- Photosystems are complexes involved in the light reactions of photosynthesis. There are two types: Photosystem I (PS I) and Photosystem II (PS II).
- PS I is primarily associated with the absorption of light and the conversion of light energy into chemical energy.

2. **Identifying the Locations**:
- PS I is found in the thylakoid membranes, specifically in the stroma lamellae, which are the regions connecting the thylakoid stacks (granum).
- PS II is also found in the thylakoid membranes but is more concentrated in the granum.

3. **Analyzing the Options**:
- **Stroma**: Both PS I and PS II are present here as they are involved in the light reactions.
- **Granulothylakoids**: Both PS I and PS II are found in the thylakoid lumen.
- **Stroma Lamellae**: This is the region where only PS I is found, as PS II does not extend into this area.
- **Matrix**: Both PS I and PS II are present in the chloroplast matrix.

4. **Conclusion**:
- The only location where only Photosystem I (PS I) is found is the **Stroma Lamellae**.

### Final Answer:
The correct option is **Stroma Lamellae**.

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