1. Which of the following bacteria can grow in acidic pH?

A. Vibrio cholerae
B. Lactobacilli
C. Shigella
D. Salmonella

2. Cell size and cell number can be measured using

A. hemocytometer
B. coulter counter
C. petroff-hausser counting chamber
D. none of these

3. 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

4. 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

5. 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