SSC MTS EXAM

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: -Phytochromes could affect flowering by altering the phase of entrainment of the circadian clock (Somers et al. 1998), thus changing the coincidence between light and a critical circadian phase. Therefore, we examined the behavior of the circadian clock in the se5 mutant.

Detailed explanation-3: -In seedlings, for example, phytochrome activation regulates approximately 10% of plant genes [18], and controls cell growth and division, chloroplast development, and circadian rhythms [3].

Detailed explanation-4: -Pfr is the active form of phytochrome which can either activate florigen production when it accumulates (long day plants) or inhibit florigen production when it accumulates (short day plants).