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
Answer: (C) (ii), (iii), (i), (iv). Answer: (C) (ii), (iii), (i), (iv).
- A.(i), (ii), (iii), (iv)
- B.(i), (iii), (ii), (iv)
- C.(ii), (iii), (i), (iv)✓
- D.(ii), (iii), (iv), (i)
Correct Answer
(C) (ii), (iii), (i), (iv)
Solution & Explanation
Answer: (C) (ii), (iii), (i), (iv). Chemical evolution proceeds from simple to complex: first organic monomers (amino acids, sugars, nitrogen bases) form from inorganic constituents (Miller's experiment), then these join into organic polymers (proteins, nucleic acids), which aggregate into protobionts (the first self-replicating non-cellular capsules), and finally DNA-based genetic systems arise. So the order is (ii) → (iii) → (i) → (iv). NCERT Reference: Ch 6 Evolution, p.111, lines 30–33: "the first form of life could have come from pre-existing non-living organic molecules ... and that formation of life was preceded by chemical evolution, i.e., formation of diverse organic molecules from inorganic constituents."