UPSC Prelims 2012 · Question 63 of 98

UPSC Prelims 2012 question on Origin of Life Elements

Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?

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Answer: B. Carbon, Hydrogen, Nitrogen

Correct Answer: Carbon, Hydrogen, Nitrogen

Carbon, hydrogen and nitrogen were primarily responsible for the origin of life on Earth.

These elements formed the basic building blocks of early organic molecules such as amino acids, proteins and nucleic acids.

1. Carbon, Hydrogen, Nitrogen — Correct

Carbon forms the backbone of organic compounds.

Hydrogen and nitrogen are also essential for amino acids, proteins and nucleic acids like DNA and RNA, which are crucial for life.

2. Oxygen-containing combinations — Incorrect

Free oxygen was largely absent in the early reducing atmosphere.

Do not confuse oxygen’s importance for modern life with its role in the earliest origin of life.

3. Sodium, Calcium or Potassium combinations — Incorrect

These elements are important for biological functions in living organisms.

However, they were not the primary elements responsible for the initial formation of life-building organic molecules.

* The Oparin-Haldane hypothesis explains chemical evolution as the origin of life from simple inorganic molecules.

* Early Earth’s atmosphere was reducing and lacked free oxygen.

* The Miller-Urey experiment showed that amino acids could form from simple gases under early Earth-like conditions.

* Important gases in the Miller-Urey experiment included methane, ammonia, hydrogen and water vapour.

* CHNOPS refers to six major elements of life: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur.

* Amino acids are the building blocks of proteins, while nucleotides form DNA and RNA.

Carbon, hydrogen and nitrogen were central to the formation of early organic molecules, making them primarily responsible for the origin of life.

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