Gce Model Questions Vol1 2019 Biology Question 37

Practice objective / multiple choice question 37 from the 2019 Gce Model Questions Vol1 Biology examination.

Gce Model Questions Vol1 2019 Biology Objective / Multiple Choice Hard Difficulty
Question 37 GCE_MODEL_QUESTIONS_VOL1 • 2019 • BIOLOGY • objective

In a batch culture a bacterium shows the following viable counts: after 2 h \(1.5\times10^{6}\) CFU ml\(^{-1}\), after 5 h \(1.2\times10^{7}\) CFU ml\(^{-1}\) and after 8 h \(9.6\times10^{7}\) CFU ml\(^{-1}\). Assuming exponential growth between 2 h and 8 h with a constant generation time, (a) calculate the generation time in minutes; (b) a second bacterium has a generation time 30 % shorter. Starting from the same initial count at 2 h, how many cells would be present after 8 h? Give the answer in scientific notation to two significant figures.

Answer Options

Correct Answer A. Generation time = 60 min; after 8 h the second bacterium would have ≈ 5.8×10⁸ CFU ml⁻¹.
B. Generation time = 70 min; after 8 h the second bacterium would have ≈ 7.2×10⁸ CFU ml⁻¹.
C. Generation time = 55 min; after 8 h the second bacterium would have ≈ 3.9×10⁸ CFU ml⁻¹.
D. Generation time = 45 min; after 8 h the second bacterium would have ≈ 4.2×10⁸ CFU ml⁻¹.
Correct Answer
A
Correct Option:
Generation time = 60 min; after 8 h the second bacterium would have ≈ 5.8×10⁸ CFU ml⁻¹.

About This Question

This is Gce Model Questions Vol1 2019 Biology Question 37. It is one of the objective questions from the 2019 Gce Model Questions Vol1 Biology examination.

Difficulty level: Hard .

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