Arrange the following historical events in the history of life in chronological order?
(A) Natural selection
(B) Self-replicating molecules
(C) Eukaryotic cell
(D) Prokaryotic cell
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (B), (A), (D), (C)
(B) Self-replicating molecules — first. Life began as giant molecules (RNA, proteins) that could copy themselves, before any cell existed.
(A) Natural selection — second. Once molecules could copy themselves, those that copied better became more common. This is natural selection acting even before cells.
(D) Prokaryotic cell — third. The first cells were simple single cells without a nucleus.
(C) Eukaryotic cell — last. Cells with a true nucleus and organelles came much later, from prokaryote-like ancestors.
Note: NCERT gives the order of self-replicating molecules, then cells. The place of natural selection between them is from beyond the NCERT textbook.
NCERT Extract:
Origin of Life – “… We have no idea about how the first self replicating metabolic capsule of life arose. The first non-cellular forms of life could have originated 3 billion years back. They would have been giant molecules (RNA, Protein, Polysaccharides, etc.). These capsules reproduced their molecules perhaps. The first cellular form of life did not possibly originate till about 2000 million years ago. These were probably single-cells.”