The wavelength of light absorbed by Pr form of phytochrome is
- 680 nm
- 720 nm
- 620 nm
- 640 nm
Answer
(1) 680 nm
Solution
Phytochrome exists in two interconvertible forms, Pr and Pfr.
Pr (red-absorbing form) absorbs red light (about 660–680 nm) and changes into Pfr.
Pfr (far-red-absorbing form) absorbs far-red light (about 730 nm) and changes back into Pr.
∴ Among the given values, Pr absorbs 680 nm (red light); 720 nm lies in the far-red region absorbed by Pfr.
Answer: (1)