A pure culture in exponential growth phase has a bacterial concentration of 6.4 x 10⁸ cells/ml.If the bacterium has a generation time of 1 h,how long ago was the cell concentration 8.0 x 10⁷ cells/ml? A)1 h B)2 h C)3 h D)4 h

Question

Quizplus · Accepted Answer

The generation time is the time it takes for the bacterial population to double. Using the formula Nt = N0 x 2^(t/g), where Nt is the final concentration, N0 is the initial concentration, t is the time, and g is the generation time, we can solve for t:

Nt = 8.0 x 10^17 cells/ml
N0 = 6.4 x 10^18 cells/ml
g = 1 hour

Nt/N0 = 2^(t/g)
8.0 x 10^17 / 6.4 x 10^18 = 2^(t/1)
0.125 = 2^t
t = 3 hours

Therefore, the cell concentration was 8.0 x 10^17 cells/ml 3 hours ago, making the correct answer choice C.

A Pure Culture in Exponential Growth Phase Has a Bacterial