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

B) exposure to red light

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.

pe = weightxheight = 2000x1000=2,000,000joules

spectral lines lyman is one set