Question

Define a reflex arc. Why have reflex arcs evolved in animals ? Trace the sequence of events which occur, when you suddenly touch a hot object.

Name the part of nervous system which helps in communication between the central nervous system and other parts of the body. What are the two components of this system ?

Leaves of chhui-mui plant begin to fold up and droop in response to a stimulus. Name the stimulus and write the cause for such a rapid movement. Is there any growth involved in the movement ?

Define geotropism in plants. What is meant by positive and negative geotropism ? Give one example of each type.