Question

Life took .................. to develop from protocells to primitive PPLO (bacteria type cell).

• A. Four billion years
• B. Five billion years
• C. One billion years
• D. Three billion years

Answer 1

The correct option is C One billion years

Chemosynthesis of self replicating nucleic acids and proteins followed by aggregation of proteins around nucleic acid resulted in origin of first life form. Also known as protovirus, eobiont or protocell, the first life forms were membrane enclosed sac of molecules that had ability to concentrate material, capture energy, carry out metabolism and to replicate the genetic material (RNA served as both genetic materials and enzymes in primitive life forms). Evolution of protocell into first bacteria like cell involves appearance of central region containing self replicating DNA, replication and transcription machinery, evolution of ribosomes and protein synthesizing machinery, mechanism of division to distribute the replicated DNA to daughter cells enclosed by a selectively permeable membrane. The above mentioned changes occupied more than one billion years from earth’s origin 4.6 billion years ago to appearance of first prokaryotic cell around 3.5 billion years ago.

Therefore, the correct answer is option C.