for all defence aspirants environment


Environment is the natural component in which biotic(living) and abiotic (non living)factors interact with each other. These interactions shape the habitat and ecosystem of an organism.


habitat is the physical environment in which an organism lives. It is an ecological or environmental area habited by particular species of plants animals, fungi etc. many habitats make up the environment. A single habitat may be common for more than organism which have similar requirements.


The biosphere is the biological component (supporting life) of earth which includes the lithosphere, hydrosphere and atmosphere.it includes all living organism on earth, together with the dead organic matter produced by them.

Biosphere is deficient at extremes of the north and south poles, the highest mountains and the deepest oceans ,since existing hostile conditions there do not support life(life is the characteristic feature of biosphere). Occasionally spores of fungi and bacteria do occur at great height beyond inactive and hence represent only dormant life.

Ecology is the branch of biology concerned with the relations of organism to one another (energy flow and mineral cycling) and to their physical surroundings (environment).

Ecology encompasses study of individual organism, population, community, ecosystem, biome and biosphere which form the various levels of ecological organization.

Levels of organizations in ecology

The five levels of ecological organization are species population, community ,ecosystem and biosphere

Individual- organism is an individual living being that has the ability to act or function independently.it may be any organism.

Species- species is a community of interbreeding organism (same species), occupying a defined area during a specific time.

Population growth rate- it is the percentage variation between the number of individuals in a population at two different times .it can be positive due to birth and/or immigration or negative due to death and/or emigration.

Population density- the number of individuals per unit area at a given time is termed as population density.

Community-communities in most instances are named after the dominant plant form(species).for e.g. a grassland community is dominated by grasses, though it may contain herbs, shrubs, and trees, along with associated insects and animals of different species. A community is not fixed or rigid.

Major communities: these are large sized and relatively independent. They depend only on the sun’s energy from outside: tropical evergreen forests.

Minor communities: these are dependent on neighbouring communities and are often called societies. They are secondary aggregations within a major community .e.g.: a mat of lichen on a cow dung pad.

Biome- biome is a large naturally occurring community of flora and fauna occupying a major habitat. e.g rainforest biome or tundra biome.

Plants and animals in a biome have common characteristics due to similar climates and can be found over a range of continents.

Biomes are distinct from habitats, because any biome can comprise a variety of habitats.

Biosphere-their biosphere is the biological component of earth which includes the lithosphere, hydrosphere and atmosphere. The biosphere includes all living organism on earth, together with the dead organic matter produced by them.

Er. HartaJ is one of the main Instructors and a part of the team At NCA. He himself has cleared the SSB process thrice, but as per his grandfather's Late Lt. Col H.S.Dhaliwal Wish he is continuing teaching and making officers. Been associated with New Careers Academy for the last 8 years, he also has been succefull in making Second and Third Generation Of officers. Once Taught by his Grandfather and Father Capt. Dhaliwal. He is know all across with students for the way he teaches and he is more of a role model for them .