Biosphere – Any living plant or animal is called an organism. The living organisms exist in a variety of habitats (living places) like land, water and air. The earth has land surface, water and air which support living organisms like plants and animals. A zone consisting of land, water, and air where life exists is called a biosphere. Biosphere includes all the living organisms of earth and all the life –supporting regions of the earth.

The biosphere consists of four parts

1. Lithosphere (land, surface or soil) – The term lithosphere in Greek “stony sphere”. The earth has soil and rocks on its surface as well as under oceans. The solid outer portion of the earth containing soil and rocks is called lithosphere. The lithosphere forms the crust of earth. The biosphere is supported by lithosphere.
2. Hydrosphere – In this region, there is a lot of water on the surface in the form of ponds, lakes, rivers, oceans, and even underground water. The region of water on the surface of earth is called hydrosphere. Most of the water is in the oceans. The life originated in this ocean water and later spread on the land and air. The organisms can exist in water at about 4km below the sea-level.                                      
3. Atmosphere – There is a mixture of gases surrounding the surface of earth. The mixture of gases is called air. The air above the surface of earth is a mixture of gases and forms the atmosphere. The air is a gaseous component of the earth. The organisms can exist up to 7 to 8 kilometers in the air above the sea-level.           
4. Living organisms (like plants and animals) – The lithosphere, the hydrosphere and the atmosphere consist of the solid, liquid and gaseous matter. The lithosphere, hydrosphere and the atmosphere of the earth, along with all the living organisms like plants and animals in them is called biosphere or sphere of life.

Components of biosphere – The biosphere has two components

1. Non living component – The non-living component of the biosphere consist of the physical environment like soil, water, and air along with the inorganic substances like carbon dioxide, nitrogen, oxygen, water, phosphorus, sulphur, sodium, potassium, calcium, and other elements present in them. The factors like sunlight, temperature, pressure, and humidity are also a sort of non-living component of the biosphere and they constitute the climatic conditions. The climate in an area along with the nature of soil and water in that area determines the types of organisms which will be found in that part of the biosphere.
2. Living component – The living component of the biosphere consist of three organisms called producers, consumers, and decomposers. The producers are plants, consumers are animals whereas decomposers are microscopic non green plants. So the living component of the biosphere consists of plants and animals.