Which of the following is correct for phytochrome conversion reaction

Options

A.
B.
C.
D.

Answer

To answer the question about the correct statement regarding the phytochrome conversion reaction, we can break down the information provided in the video transcript into a step-by-step solution.

### Step-by-Step Solution:

1. **Understanding Phytochrome**: Phytochromes are photoreceptors in plants that are sensitive to light. They exist in two forms: Pr (phytochrome red) and Pfr (phytochrome far-red).

2. **Conversion of Forms**:
- **Pr to Pfr**: When Pr absorbs red light (around 660 nm), it is converted into the active form Pfr.
- **Pfr to Pr**: Conversely, when Pfr absorbs far-red light (around 730 nm), it is converted back to the inactive form Pr.

3. **Physiological Activity**:
- The Pfr form is considered the physiologically active form of phytochrome, which means it plays a crucial role in various plant processes such as seed germination, flowering, and shade avoidance.

4. **Impact of Light**:
- The conversion reactions are crucial for plants to respond to changes in light conditions. For example, exposure to red light promotes growth and development, while far-red light can indicate shading from other plants.

5. **Conclusion**: Based on the information, the correct statement regarding phytochrome conversion reactions is that red light converts Pr to Pfr, and far-red light converts Pfr back to Pr.

### Final Answer:
The correct option regarding the phytochrome conversion reaction is **Option 3**: Red light converts phytochrome Pr to phytochrome Pfr, while far-red light converts phytochrome Pfr back to phytochrome Pr.

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