Miller's Experiment & Chemical Evolution — NEET Biology
✅ Asked in NEET 2020Oparin 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, NH3 and water vapour at 800°C. 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.
NTA tests Miller's experimental conditions and what he proved about chemical evolution. The experiment simulated early Earth's reducing atmosphere (CH₄, NH₃, H₂O) with electric discharge at 800°C to show that organic molecules (amino acids) can form from inorganic substances. Students commonly confuse what Miller created: he made amino acids, NOT life itself. The experiment only demonstrates chemical evolution (formation of organic compounds), not biological evolution or abiogenesis. Remember: Miller proved organic molecules can form spontaneously under prebiotic conditions—this was the first step toward life, supporting Oparin-Haldane's theory. Focus on which compounds he used, the temperature, and the products formed.
From his experiments, S.L. Miller produced amino acids by mixing the following in a closed flask: (NEET 2020)
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