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MCB 2010C Microbiology Final Exam Latest
2024|2025 FALL-SPRING FSW GRADED A+
What kind of media is EMB? - (ANSWER)complex, selective, and differential
What is the EMB media composed of? - (ANSWER)gelatin, lactose, and the dyes
eosin Y and methylene blue
What kind of microbe does EMB agar inhibit? - (ANSWER)gram positive
If the bacterium changes to a purple color on EMB agar, what does that mean? -
(ANSWER)The bacterium is gram negative, and ferments lactose.
What bacterial stocks turn purple on EMB agar, meaning that they ferment
lactose? - (ANSWER)Enterobacter aerogenes, Proteus vulgaris, and Esherichia coli
What sheen does E. coli give off on EMB agar? - (ANSWER)A metallic green sheen
What kind of media is MAC? - (ANSWER)Selective and differential
What is the MAC media composed of? - (ANSWER)Lactose, bile salts, neutral red,
and crystal violet.
What is the action of bile salts and crystal violet in MAC media? -
(ANSWER)Inhibits gram positive bacteria growth
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What is the pH indicator in MAC media? - (ANSWER)Neutral red
If a bacterium does alter the color of MAC media, what does this mean? -
(ANSWER)The bacterium is gram negative, lactose fermenting, lowers the pH of
the media (acidic) and changes the media from pink to red.
What bacterial stocks turn red on MAC agar, meaning that they ferment lactose
and lower pH? - (ANSWER)Escherichia coli and Enterobacter aerogenes
What is the pH indicator in PR-G tubes? - (ANSWER)Phenyl red
If the bacterium changes to a yellow color, what does this mean? pink? -
(ANSWER)If the media turns yellow, this indicates glucose fermentation, and an
acidic pH. If the media turns pink, this indicates peptone from NH3 production,
raising the pH alkaline.
What does the durham tube in the PR-G tube indicate? - (ANSWER)Gas
production indicates fermentation.
What bacterium changes yellow in PR-G media? - (ANSWER)Enterobacter
aerogenes, Escherichia coli, and proteus vulgaris (both produced gas)
What kind of media is PR-G and PR-L tubes? - (ANSWER)Differential
MCB 2010C Microbiology Final Exam Latest
2024|2025 FALL-SPRING FSW GRADED A+
What kind of media is EMB? - (ANSWER)complex, selective, and differential
What is the EMB media composed of? - (ANSWER)gelatin, lactose, and the dyes
eosin Y and methylene blue
What kind of microbe does EMB agar inhibit? - (ANSWER)gram positive
If the bacterium changes to a purple color on EMB agar, what does that mean? -
(ANSWER)The bacterium is gram negative, and ferments lactose.
What bacterial stocks turn purple on EMB agar, meaning that they ferment
lactose? - (ANSWER)Enterobacter aerogenes, Proteus vulgaris, and Esherichia coli
What sheen does E. coli give off on EMB agar? - (ANSWER)A metallic green sheen
What kind of media is MAC? - (ANSWER)Selective and differential
What is the MAC media composed of? - (ANSWER)Lactose, bile salts, neutral red,
and crystal violet.
What is the action of bile salts and crystal violet in MAC media? -
(ANSWER)Inhibits gram positive bacteria growth
, 2
What is the pH indicator in MAC media? - (ANSWER)Neutral red
If a bacterium does alter the color of MAC media, what does this mean? -
(ANSWER)The bacterium is gram negative, lactose fermenting, lowers the pH of
the media (acidic) and changes the media from pink to red.
What bacterial stocks turn red on MAC agar, meaning that they ferment lactose
and lower pH? - (ANSWER)Escherichia coli and Enterobacter aerogenes
What is the pH indicator in PR-G tubes? - (ANSWER)Phenyl red
If the bacterium changes to a yellow color, what does this mean? pink? -
(ANSWER)If the media turns yellow, this indicates glucose fermentation, and an
acidic pH. If the media turns pink, this indicates peptone from NH3 production,
raising the pH alkaline.
What does the durham tube in the PR-G tube indicate? - (ANSWER)Gas
production indicates fermentation.
What bacterium changes yellow in PR-G media? - (ANSWER)Enterobacter
aerogenes, Escherichia coli, and proteus vulgaris (both produced gas)
What kind of media is PR-G and PR-L tubes? - (ANSWER)Differential
