Question

(a) Plants do not have any nervous system but yet, if we touch a sensitive plant, some observable changes take place in its leaves. Explain how could this plant respond to the external stimuli and how it is communicated.
(b) Name the hormone that needs to be administered to
(i) increase the height of a dwarf plant.
(ii) cause rapid cell division in fruits and seeds.

Answer 1

Plaats have a hormonal system for controlling and co-ordinating the activities in plants. Plants respond to light, touch, gravitational force and other stimuli. They show two different lypes of movements, they are-
* dependent on growth and *independent of growth.
In the sensitive or 'touch - me- not' plant the leaves begin to fold up and droop an touching. It uses electrical-chemical means to convey this information from cell to cell .Some cells their shape (by changing the amount of water in them) in order for movement to happen. This type of movement is indeperident of growth called nastic movement.
(b) (i) Auxin (ii) Cytokin.