Pigment system I performs independently
(a) Non-cyclic photophosphorylation
(b) Cyclic photophosphorylation
(c) Oxidative phosphorylation
(d) Photolysis

Options

A. Non-cyclic photophosphorylation
B. Cyclic photophosphorylation
C. Oxidative phosphorylation
D. Photolysis.

Answer

To solve the question regarding which process is performed independently by pigment system I (Photosystem I or PS1), we can analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Photosystem I (PS1)**:
- Photosystem I is also known as P700 because it absorbs light at a wavelength of 700 nm. It plays a crucial role in the light-dependent reactions of photosynthesis.

2. **Analyzing Each Option**:
- **(a) Non-cyclic photophosphorylation**:
- This process involves both Photosystem I (PS1) and Photosystem II (PS2) working together. Since PS1 cannot perform this process independently, this option is incorrect.

- **(b) Cyclic photophosphorylation**:
- In cyclic photophosphorylation, only Photosystem I is involved. It absorbs light, gets excited, and transfers electrons through an electron transport chain, ultimately returning to PS1. This process produces ATP but does not produce NADPH. Since PS1 can perform this process independently, this option is correct.

- **(c) Oxidative phosphorylation**:
- This process is associated with cellular respiration and involves both PS1 and PS2. Since it requires both systems, this option is incorrect.

- **(d) Photolysis**:
- Photolysis refers to the splitting of water molecules, which is primarily associated with Photosystem II. Since this process does not involve PS1, this option is also incorrect.

3. **Conclusion**:
- The only process that Photosystem I can perform independently is cyclic photophosphorylation. Therefore, the correct answer is **(b) Cyclic photophosphorylation**.

### Final Answer:
(b) Cyclic photophosphorylation