E-PolyLearning

36. Which of the following bacteria can grow in acidic pH?
a. Vibrio cholerae
b. Lactobacilli
c. Shigella
d. Salmonella
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Answer: (b).Lactobacilli

37. Cell size and cell number can be measured using
a. hemocytometer
b. coulter counter
c. petroff-hausser counting chamber
d. none of these
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Answer: (b).coulter counter

38. Which of the following is used for the proper maintenance and preservation of pure cultures?
a. Periodic transfer to fresh media
b. Preservation by overlaying cultures with mineral oil
c. Preservation by lyophilization
d. All of the above
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Answer: (d).All of the above

39. In the process of freeze drying, a dense cell suspension is placed in small vials and is frozen at
a. -60 to -78°C
b. -20 to -30°C
c. -30 to -48°C
d. -48 to -58°C
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Answer: (a).-60 to -78°C

40. The solidifying agent commonly used in preparation of media is/are
a. agar
b. silica gel
c. both (a) and (b)
d. none of these
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Answer: (c).both (a) and (b)