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Q.
Physiologically active form of phytochrome is
BHUBHU 2007
Solution:
Phytochrome is a photoreceptive pigment which is a bright blue or bluish green pigment. Phytochrome occurs in $2$ forms ie, $P_{R}$ and $P_{F R}$ (ie, red light and for red light absorming forms) in which $P _{ FR }$ is the active form.
$P _{ R }$ absorbs red light of $660\, nm$ and $P _{ FR }$ absorbs far red light of $730 \,nm$.
Phytochrome affects many processes like stem elongation, leaf expansion, stomatal development, flowering and seed germination.