The wavelength of light absorbed by Pr form of phytochrome is

Options

A. 720nm
B. 620nm
C. 640nm
D. 680nm

Answer

**Step-by-Step Solution:**

1. **Understanding Phytochrome:** Phytochrome is a photoreceptor pigment in plants that plays a crucial role in regulating various physiological processes, including flowering. It exists in two forms: Pr (red light-absorbing) and Pfr (far-red light-absorbing).

2. **Identifying the Forms of Phytochrome:**
- Pr form: This form absorbs red light.
- Pfr form: This form absorbs far-red light.

3. **Wavelengths of Light Absorbed:**
- The Pr form of phytochrome absorbs light in the range of approximately 660 to 680 nanometers.
- The Pfr form absorbs light at around 730 nanometers.

4. **Analyzing the Options Given:**
- The question provides four options for the wavelength absorbed by the Pr form:
- 720 nanometers
- 620 nanometers
- 640 nanometers
- 680 nanometers

5. **Determining the Correct Answer:**
- Since the Pr form absorbs light primarily in the range of 660 to 680 nanometers, the correct answer from the options provided is **680 nanometers**.

6. **Conclusion:** Therefore, the wavelength of light absorbed by the Pr form of phytochrome is **680 nanometers**.

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