(a) Explain feed back mechanism for regulation of hormonal secretion with the help
of one example .
(b) State two different types of movement in plant. Mention two points of difference
between them.

Explanation

(a) The timing and amount of hormones relaased by various glands are controlled by the
'feedback mechanism' which is in-bulit in our body. Example, if the suger level in the
blood rises too much, it is detected by the cells of pancreas which responds by
producing and secreting more insulin into the blood, and as the blood suger falls to
a cartain level the secretion of insulin in reduced automatically.
(b) The plant movements made in response to external stimuli fall into two main
categories - (i) tropism and (ii) nasties .
Tropisms. A growth movements made in repsonse to external stimuli in
which the dircetion of stimulus determines the direction of response is called
tropism . So it is a directional movement.
Nasties. The movement of a plant part in response to an external stimuli in
the direction of response is not determined by the direction of stimulus is called
nastic movement.
.