Question

The most important gas for origin of life?
A. Carbon
B. Oxygen
C. Water
D. Nitrogen

Answer 1

Hint: The origin of life is an outcome of some magical events arising from non-living particles or components. The process is considered spontaneous. It all began with some chemical reactions that are a sequence which is impossible to believe.

Complete answer:
We know that Carbon is present in all the living things starting from small organisms to large animals, in the form of organic compounds. During the origin of life, two important gases – carbon dioxide and carbon monoxide were used as the primary source of carbon for producing organic compounds. At that time, the concentration/amount of oxygen in the atmosphere was very less (less than 0.1%). But all the other compounds such as carbon dioxide, carbon monoxide, hydrogen and nitrogen were present in large amounts. As the temperature was also very high, it provided energy for the chemical reactions to begin along with the energy produced by lightning. Reactions occurred among hydrogen and oxygen along with carbon and nitrogen to produce the first products – ammonia, cyanide and methane. The early life started on the surface of water which supported polymerization and hydrolyzation. All these steps were possible because the amount of oxygen was almost negligible in the atmosphere at that time.
If oxygen were present at that time, it would have oxidized all the monomers as well as polymers. Thus oxygen is the most important gas for origin of life, even at present it is a limiting factor for origin of new life. At present, oxygen is the most important gas for the survival of organisms as it helps in photosynthesis and respiration.

So the correct option is (B) Oxygen.

Note: Oxygen is the third most abundant element present on earth, only after Hydrogen and Helium. Oxygen is a reactive non-metal that forms compounds with almost all the other elements.