Question

Arrange the following events for the history of life on earth:
A. Prokaryotic cell
B. Eukaryotic cell
C. Multicellular organisms
D. Organic molecule
E. Self-replicating molecule
Choose the correct answer from the options given below:

• A. D, E, C, A, B
• B. D, E, A, B, C
• C. E, D, A, C, B
• D. D, E, A, C, B

Hint:

History of Life on Earth: Organic monomers (D) $\rightarrow$ Self-replicating RNA (E) $\rightarrow$ Prokaryotes (A) $\rightarrow$ Eukaryotes (B) $\rightarrow$ Multicellular life (C).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Prebiotic chemical evolution and the chronology of major evolutionary transitions in the history of life on Earth.
Key Formula or Approach:
\[ \text{Abiotic Organic Monomers} \rightarrow \text{RNA World (Self-Replication)} \rightarrow \text{Protocells/Prokaryotes} \rightarrow \text{Endosymbiosis/Eukaryotes} \rightarrow \text{Multicellularity} \]

Step 2: Detailed Explanation:
Chronological sequence of evolutionary milestones on Earth:
1. Step 1 (D. Organic Molecules): Abiotic prebiotic synthesis of simple organic compounds (amino acids, sugars, nitrogenous bases $\approx 4.0 - 4.2\text{ billion years ago}$).
2. Step 2 (E. Self-Replicating Molecules): Emergence of self-replicating catalytic RNA molecules ('RNA World' $\approx 3.8 - 4.0\text{ bya}$).
3. Step 3 (A. Prokaryotic Cells): First anaerobic single-celled life forms (fossil stromatolites $\approx 3.5 - 3.8\text{ bya}$).
4. Step 4 (B. Eukaryotic Cells): Emergence of complex membrane-bound cells via endosymbiosis ($\approx 1.8 - 2.0\text{ bya}$).
5. Step 5 (C. Multicellular Organisms): Evolution of metazoan multicellularity (Ediacaran/Cambrian explosion $\approx 0.6 - 1.0\text{ bya}$).
Sequence: D $\rightarrow$ E $\rightarrow$ A $\rightarrow$ B $\rightarrow$ C.

Step 3: Final Answer:
Therefore, the chronological sequence is D, E, A, B, C, corresponding to option (B).