The biosphere in its widest sense consists of the earth’s crust, the atmosphere and the various species of life that exist in the zone 600 m above and 10,000 m below sea level. The biosphere is very large and complex and, hence, is divided into smaller units called ecosystems. An ecosystem consists of plants, animals and micro-organisms that live in a definite zone along with the physical factors such as soil, water and air.
THE NATURAL CYCLES OF THE ENVIRONMENT