SSC MTS EXAM

Detailed explanation-1: -The purified phytochrome from dark-grown plants is blue in color and absorbs red light (termed Pr, absorbs maximally at 660 nm). On exposure to red light, the Pr form converts to the far-red light absorption form (Pfr) which is olive-green in color and absorbs maximally at 730 nm (Quail, 1997, Figure 2).

Detailed explanation-2: -Pfr absorbs far-red light ( 730 nm) and is quickly converted back to Pr. Absorption of red or far-red light causes a massive change to the shape of the chromophore, altering the conformation and activity of the phytochrome protein to which it is bound.

Detailed explanation-3: -In plants, red light changes phytochrome to its biologically active form, while far red light changes the protein to its biologically inactive form.