Which of the Following Treatments Would Enhance the Level of the Pfr

Question

Which of the following treatments would enhance the level of the Pfr form of phytochrome?
A)exposure to far-red light
B)exposure to red light
C)long dark period
D)inhibition of protein synthesis
E)synthesis of phosphorylating enzymes

Accepted Answer

Phytochrome exists in two forms, the Pr form and the Pfr form. The conversion of the Pr form to the Pfr form is triggered by exposure to red light, whereas exposure to far-red light reverses this conversion back to the Pr form. Therefore, exposure to red light would enhance the level of the Pfr form of phytochrome.