Metabolic reactions can be demonstrated outside the
body in cell-free systems. When an isolated metabolic
reaction is performed outside the body of an organism
in a test tube, it is neither living nor non-living. Hence,
while metabolism is a defining feature of all living
organisms without exception. isolated metabolic
reactions in vitro are not living things, but are living
reactions. Here. it can also be said that cellular
organisation of the body is the defining feature of life
forms.