Question

What is true about phytochrome?
A) $P_r$ absorbs red light and becomes Pfr
B) $P_r$ absorbs yellow light and becomes Pfr.
C) $P_fr$ absorbs yellow light and becomes Pr
D) $P_fr$ absorbs red light and becomes Pr.

Answer 1

Hint:Phytochrome is a pigment found in plants which is associated with different plant measures like seed germination. Seed germination requires adequate measure of Ppr Pr is blended by developing seeds and is changed over to Ppr at the point when presented to red light. In any case, when seeds are presented to far-red light, they won't develop as Ppr is changed over to Pr.

Complete Answer:
Phytochromes are a class of photoreceptors in plants, microorganisms and parasites used to distinguish light. They are delicate to light in the red and far-red locale of the obvious range and can be classed as either Type I, which are actuated by a wide margin red light, or Type II that are enacted by red light. Ongoing advances have recommended that phytochromes additionally go about as temperature sensors, as hotter temperatures improve their de-enactment. These elements add to the plant's capacity to grow.
Pr ingests red light (~667 nm) and is promptly changed over to Pfr. Pfr retains far-red light (~730 nm) and is immediately changed over back to Pr. Ingestion of red or far-red light makes a gigantic change in the state of the chromophore, modifying the compliance and action of the phytochrome protein to which it is bound. So, Pr absorbs red light and becomes Pfr.

So the correct answer is option ‘A’.

Note: The compound 2,4- dichlorophenoxyacetic acid ir 2,4-D is a herbicide used to kill any dicot plant tissue. It is a synthetic auxin.