Question

The most abundant element in living beings is
A. Oxygen
B. Nitrogen
C. Carbon
D. Hydrogen

Answer 1

Hint: This is the most abundant element found in the matter of the living organisms. It is used as one of the most essential processes i.e. respiration.
The gas inhaled supports the oxidation of food and releases energy.
It plays a crucial role in the organic process occurring within the mitochondria.

Complete answer: Organic molecules exist in three-dimensional space, and the same set of atoms can be put together in many recognizably different ways, resulting in molecules that build the bodies of living organisms.
The properties of different biological molecules depend on certain characteristic groupings of atoms called functional groups.
Oxygen is the most abundant element contained within living organisms, composing about 65% of the whole-body mass.
Oxygen's presence within the body is essentially stored in the form of water molecules, which is employed to supply the energy within the body needed to sustain life.

So, the correct answer is option A. Oxygen.

Note: Biological molecules, or biomolecules, are built by joining atoms through covalent bonds. Although almost 25 kinds of elements can be found in biomolecules, among them six elements are the most common: these are carbon, hydrogen, nitrogen, oxygen, phosphorus, and Sulphur.