E. coli divides every 20 minutes. If a culture containing 1 × 10⁵ cells is incubated for 100 minutes at 37°C, how many cells would be expected?

Correct option is A

Correct Answer: (a)
Explanation:
Time = 100 minutes
Division time = 20 minutes
Number of divisions = 100 ÷ 20 = 5
Initial cells = 1 × 10⁵
After 5 divisions,
N = N₀ × 2⁵ = 1 × 10⁵ × 32 = 32 × 10⁵ cells.
Information Booster:
E. coli doubles every 20 minutes in optimum conditions.
Bacterial growth is exponential – N = N₀ × 2ⁿ.
Growth curve has four phases – lag, log, stationary, decline.
Generation time varies between species and environment.
Temperature, nutrient supply, and pH affect growth rate.