Mutation that inactivates cytochrome system would

Options

A. inhibit movement of electrons from PSI to PSII
B. inbibit movement of `e^(-)` from PSII to PSI
C. promote `NADPH+H^(+)` formation
D. promote photolysis of water

Answer

### Step-by-Step Solution:

1. **Understand the Role of the Cytochrome System**: The cytochrome system is a crucial part of the electron transport chain in photosynthesis, located in the thylakoid membrane. It facilitates the transfer of electrons from plastoquinone to plastocyanin and eventually to Photosystem I (PSI).

2. **Identify the Impact of Mutation**: A mutation that inactivates the cytochrome system would disrupt the normal flow of electrons through this pathway. This means that electrons would not be able to move from plastoquinone to plastocyanin, and consequently, they would not reach PSI.

3. **Analyze the Options**:
- **Option A**: "Inhibit movement of electrons from PS1 to PS2" - This is incorrect because electrons do not flow from PS1 to PS2; they flow in the opposite direction.
- **Option B**: "Inhibit movement of electrons from PS2 to PS1" - This is correct because if the cytochrome system is inactive, the electrons cannot flow from PS2 to PS1.
- **Option C**: "Promote NADPH Formation" - This is incorrect because NADPH formation requires electrons, which would not be available if the cytochrome system is inactive.
- **Option D**: "Promote the photolysis of water" - This is also incorrect because photolysis of water requires a supply of electrons, which would be hindered if the cytochrome system is not functioning.

4. **Conclusion**: Based on the analysis of the options, the correct answer is that the mutation would inhibit the movement of electrons from PS2 to PS1.

### Final Answer:
The mutation that inactivates the cytochrome system would inhibit the movement of electrons from PS2 to PS1.

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