Which one occurs both during cyclic and non-cycclic modes of photophosphorylation

Options

A. Involvement of both `PS` I and `PS` II
B. Formation of `ATP`
C. Release of `O_(2)`
D. Formation of `NADPH`.

Answer

To answer the question "Which one occurs both during cyclic and non-cyclic modes of photophosphorylation?", we can analyze the options provided:

1. **Involvement of PS1 and PS2**:
- In non-cyclic photophosphorylation, both Photosystem I (PS1) and Photosystem II (PS2) are involved.
- In cyclic photophosphorylation, only Photosystem I (PS1) is involved.
- Therefore, this option is incorrect as it does not occur in both modes.

2. **Formation of ATP**:
- ATP is produced in both cyclic and non-cyclic photophosphorylation.
- In cyclic photophosphorylation, ATP is generated through the electron transport chain involving PS1.
- In non-cyclic photophosphorylation, ATP is also produced alongside NADPH and oxygen.
- Thus, this option is correct as it occurs in both modes.

3. **Release of Oxygen**:
- Oxygen is released only during non-cyclic photophosphorylation due to the photolysis of water.
- In cyclic photophosphorylation, there is no release of oxygen.
- Therefore, this option is incorrect.

4. **Formation of NADPH**:
- NADPH is formed only during non-cyclic photophosphorylation.
- It is not produced in cyclic photophosphorylation.
- Hence, this option is also incorrect.

Based on this analysis, the correct answer is that **formation of ATP** occurs in both cyclic and non-cyclic modes of photophosphorylation.

**Final Answer**: Formation of ATP.