We all know that living beings are bio-chemical organisms. They are made up of chemicals. A number of metabolic activities are taking place inside of us at all times. Metabolism is defined as the sum total of all chemical reactions that take place inside the body. Metabolism is purely characteristic of living beings. No living organism can exhibit metabolism.

However, these reactions can be replicated outside a living body i.e. in a cell free system. But that doesn’t make them living. The reactions do not lead to generation of life or maintenance of life hence cannot be called living.