Why are living organisms classified?

Organisms are classified to

How are single celled organism classified?

In artificial system, the organisms are classified on the basis of

[A]: The earliest living organisms were structurally simple. [R]: The earliest living organisms were more complex than present one.

The most diverse chemicals in a living organism are

Viruses are not considered to be living organisms because they are not made of

The living organisms can be undexceptionally distinguished from the non - living things on the basis of their ability for

A completely free living organism which takes part in nitrogen fixation is

Smallest free living organism is

How can living organisms be distinguished from non-living organisms?