Question

Which compound has very important role in prebiotic evolution?
A. Sulphur dioxide
B. Nitric oxide
C. Methane
D. Sulphur trioxide

Answer 1

Evolution is defined as slow and gradual changes in the living forms. The first evolution in the normal conditions on earth is defined as prebiotic evolution that is before the evolution of the living organisms. Chemical evolution is defined as the formation of diverse organic molecules from inorganic constituents.

Step by step answer: The prebiotic evolution S.L Miller conducted an experiment that has the same condition as that were naturally present on Earth and required for evolution. Miller sealed in a spark chamber a mixture of water $\mathop H\nolimits_2 \mathop O\nolimits^{}$, methane $\mathop {CH}\nolimits_4$, ammonia $\mathop {NH}\nolimits_3$ and hydrogen gas $\mathop H\nolimits_2 \mathop O\nolimits^{}$. He made arrangements for a mixture of two electrodes to provide electrical energy (simulation of lightning) to the spark chamber. $\mathop {CH}\nolimits_4$, and $\mathop {NH}\nolimits_3$ were in 2 : 1 : 2 ratio and water vapour at 800°C. Electric sparks of 75,000 volts were provided to the mixture. The spark chamber was connected to another flask with an arrangement for boiling water (provision for evaporation). When this experiment was performed a significant amount of amino acids are produced. So, this shows evolution.
i. Sulphur dioxide:- Miller does not show the presence of this gas in his experiment. The evolution also occurred without this gas. So it is not required for prebiotic evolution.
ii. Nitric oxide:- All the necessary amino acids were synthesized in the absence of this gas.
iii. Methane:- Miller showed the presence of four gases in his experiment. One of them is methane that is $\mathop {CH}\nolimits_4$. This gas results in the formation of amino acids such as alanine, glycine that show evolution.
iv. Sulphur trioxide:- Miller does not show the presence of this gas in his experiment. The evolution also occurred without this gas.
Hence option C is correct.

Note: The experiments of Miller and other scientists demonstrate that prebiotic molecules could have been formed under the conditions which most likely existed on early Earth. Still, the formation of prebiotic molecules does not essentially lead to the origin of life. For the origin of life, at least three conditions needed to have been fulfilled:
1. There must have been a supply of self-replicators i.e., self-producing molecules.
2. Copying of these replicators must have been subject to error via mutation.
3. The system of replicators must have required a perpetual supply of free energy and partial isolation from the general environment