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1. Which type of growth media is selective for Gram-positive bacteria?
 A. MacConkey Agar
 B. Mannitol Salt Agar
 C. Eosin Methylene Blue Agar
 D. Sabouraud Dextrose Agar
 Answer: B. Mannitol Salt Agar
 Rationale: Mannitol Salt Agar is high in salt concentration, which
inhibits the growth of most Gram-negative bacteria, thus selecting for
Gram-positive bacteria.
2. What is the purpose of using a candle jar in microbial cultivation?
 A. To increase the carbon dioxide concentration
 B. To decrease the oxygen concentration
 C. To maintain a neutral pH
 D. To sterilize the growth media
 Answer: A. To increase the carbon dioxide concentration
 Rationale: A candle jar is used to create an environment with increased
CO2, which is beneficial for the growth of certain bacteria that require
elevated levels of carbon dioxide.
3. In the context of microbial growth media, what does the term
'differential' mean?
 A. The media differentiates between living and dead cells.
 B. The media allows for the differentiation of species based on
metabolic properties.
 C. The media can be used for a variety of different microbes.
 D. The media differentiates between aerobic and anaerobic growth.
 Answer: B. The media allows for the differentiation of species based on
metabolic properties.
 Rationale: Differential media contain indicators that reveal differences
between organisms, such as changes in pH that indicate the fermentation
of a specific sugar.
4. Which of the following is NOT a characteristic of a chemically defined
media?
 A. The exact chemical composition is known.
 B. It contains extracts or digests of animals, plants, or yeasts.
 C. It supports the growth of a wide range of microorganisms.
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