Growth and Nutrition of Bacteria – Section 1

26. Which of the following has more tolerance for acidic pH (lower pH)?

A. Yeast and molds
B. Bacteria
C. E. coli
D. None of these

Correct Answer: A. Yeast and molds

27. The ability of Vibrio fischeri to produce bioluminescence chemicals only when a certain population density has been reached is an example of

A. Liebig’s law of the minimum
B. Shelford’s law of tolerance
C. quorum sensing
D. Heisenberg’s principle of uncertainty

Correct Answer: C. quorum sensing

28. Antimicrobial constituents for the microbial growth in foods are

A. intrinsic factor
B. extrinsic factor
C. both (a) and (b)
D. none of these

Correct Answer: A. intrinsic factor

29. The average size of cells during the exponential phase of growth is

A. greater than the lag phase
B. lesser than the lag phase
C. equal to the lag phase
D. none of these

Correct Answer: B. lesser than the lag phase

30. A culture broth tube was very turbid at the surface but clear throughout the rest of the tube indicating that the

A. organism are aerobes
B. organism should be grown in an anaerobic chamber
C. organism cannot produce superoxide dismutase and/or catalase
D. organism cannot tolerate oxygen

Correct Answer: A. organism are aerobes

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