Multiple choice

In an actively growing (exponential phase) yeast culture, the cell concentration increased from 103 cells per ml to 107 cells per ml in 4 h. The doubling time of the yeast is

  1. 120 minutes

  2. 30 minutes

  3. 18 minutes

  4. 60 minutes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During exponential growth, cell concentration follows N = N0 times 2^(t/td). Here, 10^7 equals 10^3 times 2^(4/td), which means 10^4 equals 2^(4/td). Taking logarithms and solving for td gives 4 hours divided by (4 times log2(10)), resulting in 18 minutes.

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