ORGANISM AND ENVIRONMENT
Everything surrounding us forms our environment. There are two types of environment which are recognized, the non-living environment and the living environment. The relation between these two environments is very intimate. The main factors of non-living environment are soil, water and air which provide food and shelter to the living organisms.
The environment influences our life deeply. We get all kinds of things from the environment that helps us to stay alive. Different types of animals grow in different environments, e.g. rivers, canals, lakes, ponds etc., which are able to meet the requirements of different aquatic animals but the terrestrial animals cannot live in this type of environment. There is scarcity of water in the desert, so the number of plants growing in the desert is very limited. In this type of environment, plants are rarely seen. Aquatic animals and plants are almost rare.
If we observe, we will notice that both plants and animals living in the saline soil of the Sundarbans are not found in the forests of Sylhet and Chittagong Hill tracts. From this, it is understood that the organisms, which grow and live in some particular natural environment have their own individuality. In this way, different organisms (plants or animals) together form a biotic community. Each community consists of plants, animals and micro-organisms. They live together in co-operation with one another. The climatic condition of a particular geographical region depends upon the topography and configuration of that region. The animals and plants of a particular region are influenced by the climate of their habitat.
Besides, the animals of that region also have influence upon the plants. In this way the inseparable relation between the environment and the biotic community of a particular region is formed. The biotic community and its non-living environment are dependable on each other.
You have learnt before that the size and nature of the plants and animals depend on their environment. All the regions of the world are not similar. Sundari, garan and gewa plants are found in the Sundarbans. The rivers of this forest have crocodiles, Royal Bengal Tiger and spotted deer are found on this land. These animals and plants are not found in the forests of Sylhet and Madhupur. Why is this so? It is very natural to ask such a question. All these happen due to the diversity of a particular environment.
The organisms return all the elements that they have taken from the environment. It becomes difficult to survive for the plants and animals if the environment lacks any biological or physical factors. The plants absorb nutrition from the fertile soil. The animals in turn get their food from the plants. Through this mutual co-operation the plants and animals grow.
Due to overpopulation, human habitation and number of industries have increased. For this reason the areas of traditional cultivable land and natural forests have decreased. Sound, smoke, industrial waste, garbage and bad smell of the factories etc. are polluting the environment. As a result the balance of environment is being disrupted.
The different animals of the world are not only dependable on one another, they are also dependable upon the physical factors of the environment e.g. soil, water, air and plants. For this reason, living beings cannot be separated from the nonliving. There is an intimate relationship between the living community and the non living environment for survival. The inter relationship between organisms and their environment is ecology.