Expert: Walter Hintz - 3/14/2008

Question
Oxygen is the third largest Gas in our atmosphere. Then why did all organism evolve to use Oxygen as a source to live? Why not nitrogen? Why didnt our bodies develop as such to use Nitrogen?

Thanks Sudip

Answer
Hi sudip;
Why questions are always tough and are in the realm of evolutionary biology but the answer lies in the way in which oxygen and nitrogen combine with other molecules.  Life processes require energy and the release of energy comes about through the combining of oxygen with organic compounds (oxidation)  Nitrogen will not do this.