Biosphere is the highest level of organisation. It consists of all the living organisms of world along with their physical environment. Before we try to understand biosphere, let us first recall the terms like organism, population, biotic community, ecosystem and biome.

1. Individual Organism:

An individual is a distinct entity capable out life processes.

All the individuals of a particular kind form a species.


2. Population:

Population is the next higher level of organism. An individual cannot live in isolation in nature. For its survival and multiplication, an individual often associates with other individuals of its own kind. All the individuals of a particular kind living at a place, which form a single interbreeding group, constitute a population. Thus,

Population is a group of interbreeding individuals having common characteristics and living together at a place.

For example, all the frogs living in a particular pond constitute one population of frogs. Organisms of a particular kind may form several populations’ inhabitating different geographical areas. For example, frogs found in a pond, a lake and a marsh are different populations of the same organism, frog. A species includes all the population of a particular individual.


3. Biotic Community:

Various populations of different species living together from a biotic community. They interact with one another and share the same habitat and environmental conditions. A biotic community includes only living entities (organisms). If non-living factors are also considered with the living beings, then we are dealing with ecosystem. Thus,

Biotic community may be defined as various populations of different species living together within the same habitat.

For example, the population of various species such as frogs, fishes, snakes, turtles, etc. living in a pond constitutes a biotic community.