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.
What is meant by reflex action? Give one example.
A spontaneous, mechanical and automatic response to a stimulus controlled by the spinal cord without the involvement of the brain is called reflex action.
For eg. Watering of mouth while seeing tasty food.