What is meant by stimulus and reaction?
Stimulus is the change in the environment or environmental factors to to which the organism can respond or react. Theresponse shown by organisms towards or awaya stimulus is called reaction.
Pituitary gland is called master glands. Why?
We all know, the pituitary gland controls and stimulates many activities of the body and the secretion of other endocrine glands too. So, it is called master gland.