The word ‘environment’ is derived from the French word environ, which means ‘to surround’ or ‘around’ and is referred to as the external conditions in which an organism lives. Environment thus, can be defined as the sum total of physical, chemical and biological factors, which act upon an organism or an ecological community and determine its form and nature of survival. Animate and inanimate objects together constitute the natural environment making even human beings a part of the environment. Man is the most advanced of all living beings and is considered to be a social animal.
Therefore, it can be said that man lives in a socio-cultural environment that either directly or indirectly affects him. In turn, human beings also change or modify the nature Of environment to suit their requirements. However, these changes are not always beneficial. ‘ The environment never remains static for any living organism; it changes with time as well as changes from place to place. We live in a state of dynamic equilibrium with the environment.
The organism thus, has to make adjustments in response to the changes in one or more environmental factor(s) such as temperature, humidity, pH, etc. N order to survive, grow, feed and reproduce. Plants and animals, just like human beings, draw nourishment from the environment and survive in its lap. They grow, develop, reproduce and ultimately perish in the environment. Organisms differ widely in their response to environmental changes.
Some organisms are very sensitive to even the slightest environmental change, while others have the ability to modulate their metabolic processes and cope with these changes. Species which could not cope with a change in environment have either become extinct or are on the verge of extinction.