21. A medium containing crystal violet dye plus sodium deoxycholate will allow
A. gram (-)ve intestinal bacteria to grow
B. gram (+)ve intestinal bacteria to grow
C. aquatic bacteria to grow
D. none of these
22. Which of the following bacteria can grow in alkaline pH?
A. Shigella
B. Lactobacilli
C. Salmonella
D. Vibrio cholerae
23. All bacteria that inhabit the human body are
A. heterotrophs
B. chemolithotrophs
C. autotrophs
D. phototroph
24. When a substance is added to a liquid medium which inhibits the growth of unwanted bacteria and favors the growth of wanted bacteria, it is known as
A. differential medium
B. enriched medium
C. enrichment medium
D. selective medium
25. Which of the following methods is most likely to be quantitative?
A. Dilution and plating
B. Gram staining
C. Wet mount
D. None of these