Question

Which of the following treatments would enhance the level of the Pfr form of phytochrome?A) exposure to far-red lightB) exposure to red lightC) long dark periodD) inhibition of protein synthesisE) synthesis of phosphorylating enzymes

Answer 1

B) exposure to red light

Step-by-step explanation:

Plants use a phytochrome system to sense the level, intensity, duration, and color of environmental light do as to adjust their physiology.

The phytochromes are a family of chromoproteins with a linear tetrapyrrole chromophore, similar to the chlorophyll. Phytochromes have two photo-interconvertible forms: Pr and Pfr. Pr absorbs red light (~667 nm) and is immediately converted to Pfr. 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. Together, the two forms represent the phytochrome system.