In: Biology
1. What are short-day and long-day plants? How interrupting the night with a flash of light affect flowering in these plants?
2. Define plant phototropism. Describe a simple experiment to demonstrate phototropism in plants.
1. Answer- Short day plants are the plants which requires less photo period time than critical photo period time for flowering. It means short day plants flower when plants are exposed to long periods of darkness and short periods of light.
Long day plants are the plants which requires more photo period time than critical photo period time for flowering. It means long day plants flower when plants are exposed to long periods of light and short periods of darkness.
If interruption of night with a flash of light will occur in Short day plants then there will be no flowering in case of short day plants whereas interruption of night with a flash of light in long day plants will allow for flowering.
2. Answer- Plant phototropism means growth of plant towards stimulus of light. This is of two type- positive phototropism means response of plant in direction of light source like movement of shoot whereas negative phototropism means response of plant away from the light source as example- growth of root.
Simple experiment to demonstrate phototropism in plants-
Take any small plant in flower pot and keep in dark room and allow the light to come from window only. It can be observed after two week that movement of growth of shoot is towards the direction of light, so there is bending of stem of plant toward the direction of light which shows the effect of phototropism.