a] Name the two main constituents of the Central Nervous System in human beings.
b] What is the need for a system of control and coordination in human beings?

Explanation

a] The two main constituents of the Central Nervous System in human beings are the brain and the spinal cord.
b] A living being does not live in isolation. It has to constantly interact with its external environment and has to respond properly for its survival. For example, when a hungry lion spots a deer, the lion has to quickly make a move so that it can have its food. On the other hand, the deer needs to quickly make a move to run for its life. The responses which a living being makes in relation to external stimuli are controlled and coordinated by a system, especially in complex animals. So, control and coordination is essential in maintaining a state of stability and a steady state between the internal conditions of an organism and the external environment.