Which of the following is the correct sequence of events in the origin of life ? I. Formation of protobionts II. Synthesis of organic monomers III. Synthesis of organic polymers IV. Formation of DNA-based genetic systems
- II, III, I, IV
- II, III, IV, I
- I, II, III, IV
- I, III, II, IV
Answer
(1) II, III, I, IV
Solution
As per the Oparin–Haldane theory, the first form of life arose by chemical evolution from inorganic constituents.
First simple organic monomers (amino acids, sugars, bases) were synthesised (II), and these joined to form organic polymers (proteins, nucleic acids) (III).
The polymers then gave rise to protobionts / coacervates, the precursors of cells (I), and finally the genetic system was formed; the earliest system was RNA-based and DNA-based genetic systems evolved later (IV).
∴ Sequence: II, III, I, IV
Answer: (1)