Question

How does carbon exist in all life forms ?

Answer 1

Carbon is a nonmetal with tetra valency and having catenation property, exist or found in various life forms . it occurs in the elemental form as diamonds and graphite , In the combined state it is found in CO2. All life forms are based on carbon containing molecules like carbohydrates, fats, nucleic acids and vitamins.
All life on earth can be thought as carbon based.