Constituents of pigment system I are located on

Options

A. Granal thylakoids
B. Stromal thylakoids
C. Outer surface of granal and stromal thylakoids
D. Stroma.

Answer

To answer the question regarding the location of the constituents of pigment system I (Photosystem I), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photosystem I (PS I)**:
- Photosystem I is one of the two photosystems involved in photosynthesis, the other being Photosystem II. PS I is crucial for the light-dependent reactions of photosynthesis.

2. **Components of Photosystem I**:
- Photosystem I consists of a central core complex and light-harvesting complexes. The central core complex contains proteins, two special chlorophyll a molecules, and a primary electron acceptor.

3. **Location of Photosystem I**:
- The constituents of Photosystem I are located in the thylakoid membranes of chloroplasts. Specifically, they are found on the outer surface of the thylakoid membranes, which are organized into structures called grana.

4. **Identifying the Correct Option**:
- The question provides four options regarding the location of the constituents of Photosystem I:
1. Granule thylakoids
2. Stromal thylakoids
3. Outer surface of granule and stromal thylakoids
4. Stroma
- Based on our understanding, the correct answer is that the constituents of Photosystem I are located on the outer surface of granule and stromal thylakoids.

5. **Conclusion**:
- Therefore, the correct answer to the question is option 3: "Outer surface of granule and stromal thylakoids."