Question

If a tree flowers thrice in a year (Oct., Jan. and July) in Northern India, it is said to be

(a) photo and thermo-insensitive

(b) photo and thermo-sensitive

(c) photosensitive but thermo-insensitive

(d) thermosensitive but photo-insensitive.

Answer 1

Answer:(d) thermosensitive but photo-insensitive

Since the flowering is taking place in different parts of the year,like the month of January,October and July which is almost a part of all the seasons.Therefore plant is not sensitive to photo-period.But these are thermosenitive.Photoperiodism is the physiological reaction of organisms to the length of day or night.Many flowering plants (angiosperms) use a photoreceptor protein, such as phytochrome or cryptochrome, to sense seasonal changes in night length, or photoperiod, which they take as signals to flower.