The shorter generation time of E. coli compared to eukaryotes may be explained on the basis of

1. Shape
2. Large surface: volume ratio
3. Presence of cell wall
4. Absence of organelles

Do explain your answer.

Prokaryotes have large surface area to volume ratio and it is responsible for their high metabolic rate, high growth rate and short generation time. This helps them to have shorter generation time or the doubling time as compared to the eukaryotes.