Identify the statements which hold true with respect to origin of life.

(A) Louis Pasteur demonstrated that life comes only from pre-existing life.
(B) Big Bang theory attempts to explain the origin of universe.
(C) Oparin and Haldane proposed first form of life came from pre-existing non-living organic molecules.
(D) Miller's experiment was unable to prove chemical evolution.

Choose the correct answer from the options given below:

(A), (B) and (C) only

The correct answer is Option (3) → (A), (B) and (C) only

Louis Pasteur by careful experimentation demonstrated that life comes only from pre-existing life. He showed that in pre-sterilised flasks, life did not come from killed yeast while in another flask open to air, new living organisms arose from ‘killed yeast’. Spontaneous generation theory was dismissed once and for all.

The universe is very old – almost 20 billion years old. Huge clusters of galaxies comprise the universe. Galaxies contain stars and clouds of gas and dust. Considering the size of universe, earth is indeed a speck. The Big Bang theory attempts to explain to us the origin of universe. It talks of a singular huge explosion unimaginable in physical terms. The universe expanded and hence, the temperature came down.

Oparin of Russia and Haldane of England proposed that the first form of life could have come from pre-existing non-living organic molecules (e.g. RNA, protein, etc.) and that formation of life was preceded by chemical evolution, i.e., formation of diverse organic molecules from inorganic constituents. The conditions on earth were – high temperature, volcanic storms, reducing atmosphere containing CH₄, NH₃, etc.

In 1953, S.L. Miller, an American scientist created similar conditions in a laboratory scale . He created electric discharge in a closed flask containing CH₄, H₂, NH₃ and water vapour at 800^oC. He observed formation of amino acids. In similar experiments others observed, formation of sugars, nitrogen bases, pigment and fats. Analysis of meteorite content also revealed similar compounds indicating that similar processes are occurring elsewhere in space. With this limited evidence, the first part of the conjectured story, i.e., chemical evolution was more or less accepted.