1.1 Environment

• Environment is the natural component in which biotic (living) and abiotic (non-living)factors interact among themselves and with each other.

• These interactions shape the habitat and ecosystem of an organism.

• In biological sense, environment constitutes the physical (nutrients, water, air) and biological factors (biomolecules, organisms) along with their chemical interactions (chemical cycles – carbon cycle, nitrogen cycle etc.) that affect an organism or a group of organisms.

• All organisms are dependent on the environment to carry out their natural life processes and to meet their physical requirements (food, energy, water, oxygen, shelter etc.).

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Biosphere

• The biosphere is the biological component(supporting life) of earth which includes the lithosphere, hydrosphere and atmosphere.

The biosphere includes all living organisms on earth,together with the dead organic matter produced by them.

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Biosphere (Source)

• Biosphere is absent 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 bio- sphere).

• Occasionally spores of fungi and bacteria do occur at great height beyond 8,000 metres, but they are metabolically inactive, and hence represent only dormant life.

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Habitat

• Habitat is the physical environment in which an organism lives (address of an organism).

• Many habitats make up the environment.

• A single habitat may be common for more than one organism which have similar requirements.

• For example, a single aquatic habitat may support a fish,frog, crab, phytoplankton and many others.