Answer: Activating FT (florigen) transcription in leaves only in long-day conditions when CO protein accumulates in the light (CO is degraded in dark by COP1).
- A Directly activating the entire complete set of vegetative growth genes simultaneously, all at the exact same developmental time under usual circumstances
- B Activating FT (florigen) transcription in leaves only in long-day conditions when CO protein accumulates in the light (CO is degraded in dark by COP1)
- C Inhibiting gibberellin biosynthesis specifically within the actively dividing cells of the shoot apical meristem region according to most researchers
- D Directly triggering the onset of meiosis within developing reproductive cells of the flower, bypassing other key signals in the majority of cases studied
Correct answer: B. Activating FT (florigen) transcription in leaves only in long-day conditions when CO protein accumulates in the light (CO is degraded in dark by COP1)
Explanation: CO protein: transcribed constitutively, but protein is rapidly degraded in dark by COP1 E3 ligase. In long days, CO accumulates in evening light, activating FT transcription. FT moves to apex to trigger flowering.
Double fertilisation in angiosperms: one male gamete fuses with the egg to form the diploid zygote (syngamy), while the second fuses with the two polar nuclei to form the triploid primary endosperm nucleus (triple fusion). Image: Triploid, CC BY 3.0, via Wikimedia Commons.
Concept context
Flower structure, pollination, double fertilization, and seed/fruit development - the highest-scoring Class 12 biology chapter in NEET.
Read the full Sexual Reproduction in Flowering Plants notes →