Elements Found in Living Organisms

Out of approximately 100 chemical elements, about 20 are found in living organisms. (Actually not all of them are present in every organism. The elements available in each organism differ by nature) These elements could be divided into 2 major groups as Macro Elements and Micro Elements, according to their presence within organisms. 

Macro Elements

Hydrogen(H), Carbon(C), Oxygen(O), Nitrogen(N), Phosphorus(P) and Sulphur(S) are contained in about 90% of body weight of an organism, and these elements are considered as the 6 most abundant elements in living matter. Including them, the elements present in comparatively large amounts within organisms, usually more than 0.01% of the dry weight (0.01% inclusive), are considered as Macro Elements.

In plants, Hydrogen(H), Carbon(C), Oxygen(O), Nitrogen(N), Phosphorus(P), Sulphur(S), Potassium(K), Calcium(Ca) and Magnesium(Mg) are considered as Macro Elements. In animals, in addition to the above elements, Sodium(Na), Ferrous(Fe) and Chlorine(Cl) are available as Macro Elements.

Micro/Trace Elements

The availability of this kind of elements are in very small amounts; usually less than 0.01% of the dry weight. But though they are of small amounts, they are essential to complete the life cycle.

Boron(B), Manganese(Mn), Zinc(Zn), Copper(Cu), Molybdenum(Mo), Aluminium(Al), Silicon(Si) and Vanadium(V) are considered as Micro Elements in animals. In plants, in addition to them, Sodium(Na), Ferrous(Fe) and Chlorine(Cl) can be termed as Micro Elements.