In which of the following aspect PS-I and PS-II differ to each other ?

Options

A. Reaction centre
B. Location on thylakoid membrane
C. Redox behaviour
D. All the above

Answer

To answer the question regarding the differences between Photosystem I (PS-I) and Photosystem II (PS-II), we can break down the aspects in which they differ into several key points:

### Step-by-Step Solution:

1. **Reaction Center Pigments**:
- PS-I has a reaction center known as P700, while PS-II has a reaction center known as P680. This difference in pigment composition is crucial for their function in photosynthesis.

2. **Location in Thylakoid Membrane**:
- PS-I is located in the outer thylakoid membrane, whereas PS-II is found in the inner thylakoid membrane. This spatial arrangement plays a role in the flow of electrons during the light-dependent reactions.

3. **Photolysis of Water**:
- PS-II is directly involved in the photolysis of water, which is the process of splitting water molecules to release oxygen. This is not a function of PS-I, which does not participate in this process.

4. **Types of Photophosphorylation**:
- PS-I can participate in both cyclic and non-cyclic photophosphorylation, while PS-II is only involved in non-cyclic photophosphorylation. This distinction affects how energy is captured and utilized in the photosynthetic process.

5. **Role in Electron Transport Chain**:
- PS-II initiates the electron transport chain by capturing light energy and facilitating the transfer of electrons, which ultimately leads to the production of ATP and NADPH. PS-I, on the other hand, receives electrons from the electron transport chain and can recycle them back in the cyclic pathway.

### Conclusion:
Based on these differences, we can conclude that the aspects in which PS-I and PS-II differ include their reaction center pigments, location in the thylakoid membrane, involvement in photolysis of water, types of photophosphorylation, and their roles in the electron transport chain.