Why is metabolism considered the main sign of life?

All due to the fact that only in the presence of metabolism other life processes are possible. During metabolism, organisms receive the necessary compounds for energy or for the creation of proteins. If you remove the metabolism from the body, then it will use up its small supply and after a while will die. Metabolism has both heterotrophs, which absorb ready-made organic substances, and autotrophs, which synthesize them on their own. Autotrophs absorb inorganic compounds and can release organic and inorganic substances.