BOTANY
PLANT REPRODUCTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Pfr is converted by red light to Pr which acts as a promoter of flowering.
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Pr is converted by red light to Pfr which acts as an inhibitor of flowering.
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Pr is converted by red light to Pfr which acts as a promoter of flowering.
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Pfr is converted by red light to Pr which acts as an inhibitor of flowering.
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Detailed explanation-1: -1: Phytochrome system: The biologically-inactive form of phytochrome (Pr) is converted to the biologically-active form Pfr under illumination with red light. Far-red light and darkness convert the molecule back to the inactive form. The phytochrome system acts as a biological light switch.
Detailed explanation-2: -Red light from the sun converts the chromoprotein into Pfr (active form), so plants grow towards the sunlight. It stimulates the growth of the plant. Plants grow slowly in shade as soon as the dormant form (Pr) is produced. When a seed experiences light with the help of the phytochrome system, it germinates.
Detailed explanation-3: -In long day plants, the active form of the phytochrome pigment, leads to transcription of a gene that controls flowering (FT gene). The FT mRNA is transported to the shoot apical meristem in the phloem, where it is translated into the FT protein.
Detailed explanation-4: -A low phytochrome photoequilibrium (Pfr/Ptot), attained by a far-red irradiation at the close of long days under fluorescent light, also promotes flowering.
Detailed explanation-5: -During long periods of darkness (long nights), Pfr is converted to Pr. With Pfr no longer present, flowering is not suppressed, and short-day plants flower. If a flash of light interrupts the dark period, Pr is converted back to Pfr, and flowering is suppressed.