CBSE Class 10 Answered

Nervous coordination by itself is insufficient to communicate informations within the body. Due to certain limitations of the use of of electrical impulses, chemical coordination is also required.

Chemical coordination involves communication through hormones. It does not require any specialised tissue like nervous tissue for the signalling to take place.

Nervous coordination is very rapid but after an electrical impulse is generatted in a cell and transmitted, the cell needs some time to reset its mechanism before it can continue with further signalling. Chemical coordination on the other hand is slow but can take place continously.

Nervous coordination is limited to only those regions which are connected by nerves while chemical coordination can take place throughout the body because hormones travel through blood.

Chemical coordination uses a wide variety of cell surface receptors so as to carry out different types of functions.

Chemical coordination can be done steadily and persistently.

In plants, chemical coordination takes place through plant hormones. Different plant hormones help to coordinate growth, development and responses to the environment. They are synthesised at places away from where they act and simply diffuse to the area of action.

The principal plant hormones are auxins, cytokinins, gibberellins, abscisic acid and ethylene. Each of these are responsible for bringing about different functions in the plant body and thereby effecting their overall growth and development.