Control and Coordination

To coordinate our internal activities, we need a system which influences every cell in the body. For this our body secrets many chemicals. We call them hormones. These Hormones can reach every cell unlike of nerve fibers which reach only to some cells.

Roots of the plant grow in the presence of water. As a result, they tend to increase in the direction where water is available. The reason for growing root towards the earth, Gravitropism is also because of water.