Choose correct statements writ. phytochromes.
A. They absorbs both far-red and red lights
B. The Pfr form is physiologically active and is present in cytosol
C. The Pfr form is physiologically active and is attached to plasma membrane
D. For LDP Pfr/Pr > 1

Options

A. A, B and C are correct
B. A, C and D are correct
C. A, B and D are correct
D. B and D are correct

Answer

To solve the question regarding phytochromes, we need to evaluate each statement provided and determine which ones are correct.

### Step-by-step Solution:

1. **Evaluate Statement A: "They absorb both far-red and red lights."**
- Phytochromes exist in two forms: Pr (red light-absorbing form) and Pfr (far-red light-absorbing form).
- Pr absorbs red light at around 660 nm, while Pfr absorbs far-red light at around 730 nm.
- **Conclusion:** This statement is **correct**.

2. **Evaluate Statement B: "The Pfr form is physiologically active and is present in cytosol."**
- The Pfr form of phytochrome is indeed the physiologically active form.
- It is found in the cytosol and can be transported to the nucleus upon activation by light.
- **Conclusion:** This statement is **correct**.

3. **Evaluate Statement C: "The Pfr form is physiologically active and is attached to plasma membrane."**
- While Pfr is physiologically active, it is not attached to the plasma membrane; it primarily functions in the cytosol and nucleus.
- **Conclusion:** This statement is **incorrect**.

4. **Evaluate Statement D: "For LDP Pfr/Pr > 1."**
- In long-day plants (LDP), the ratio of Pfr to Pr is indeed greater than 1, which is necessary for the flowering process.
- **Conclusion:** This statement is **correct**.

### Summary of Correct Statements:
- The correct statements are A, B, and D.

### Final Answer:
The correct statements regarding phytochromes are A, B, and D.

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