MICROBIOLOGY LAB FINAL EXAM VERSION
2 2025/2026 WITH ACTUAL CORRECT
QUESTIONS AND VERIFIED DETAILED
ANSWERS |FREQUENTLY TESTED
QUESTIONS AND SOLUTIONS |ALREADY
GRADED A+|NEWEST|BRAND NEW
VERSION!!|LATEST UPDATE
(FTM/Catalase)
Growth is only seen below the oxygen zone in the FTM tube. This organism doesn't utilize
oxygen for its metabolism it is killed by oxygen. This doesn't have catalase. This organism is
negative for the catalase test.
Which of the following classifications best fits this description?
Obligate (strict) anaerobes
(FTM/catalase)
Growth at the top of the FTM tube only within the oxygen zone only, therefore the organism
requires oxygen for growth. This organism uses an electron transport chain with oxygen as the
final electron acceptor. This organism also requires the enzyme catalase to protect it from toxic
forms of oxygen. This organism is positive for the catalase test.
Which of the following classifications best fits this description?
Obligate (strict) aerobes
(FTM/catalase)
More growth at the top of the FTM tube in the oxygen zone is seen than in the non-oxygen
zone, therefore the organism can grow better in the presence of oxygen but doesn't require it
for growth. This organism uses an electron transport chain with oxygen as the final electron
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,acceptor when oxygen is present. This organism also requires the enzyme catalase to protect it
from toxic forms of oxygen. This organism is positive for the catalase test.
Which of the following classifications best fits this description?
Facultative anearobes
(Methyl Red)
What is the pH indicator for this test?
Methyl Red
(Methyl Red)
What color is the medium prior to addition of the pH indicator?
Yellow
(Methyl Red)
What color is the pH indicator in the dropper bottle?
red
(Methyl Red)
After adding two drops of pH indicator to the culture medium, what color indicates that an
organism has caused a significant drop in pH of the medium (below 4.4) due to the prolific
production of acids?
Red
(Methyl Red)
What color indicates that the pH of the culture medium has not dropped below 4.4?
yellow
(Methyl Red)
Can a Methyl-Red Negative organism cause the pH of the MR-VP culture medium to drop at all
from its initial value?
yes
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, (Methyl Red)
Would you expect a Methyl-Red positive organism to be Phenol-Red positive for acid
production?
yes
(Methyl Red)
Does a Phenol-Red+ organism have to be Methyl-Red+?
no
Red color after adding pH indicator, organims produced multiple acids from the fermentation of
glucose that dropped the pH to 4.4 or below
positive for acid fermenation
yellow color after adding pH indicator, organism didn't produce multiple acids form the
frementation of glucose pH is 4.5 or above
negative for mixed acid fermenation
(Voges-Proskauer)
What is Barritt's Reagent A?
alpha-naphthol
(Voges-Proskauer)
How many drops did you add of Reagent A?
15
(Voges-Proskauer)
What is Barritt's Reagent B?
potassium hydroxide (KOH)
Voges-Proskauer)
How many drops did you add of Reagent B?
5
3|Page
2 2025/2026 WITH ACTUAL CORRECT
QUESTIONS AND VERIFIED DETAILED
ANSWERS |FREQUENTLY TESTED
QUESTIONS AND SOLUTIONS |ALREADY
GRADED A+|NEWEST|BRAND NEW
VERSION!!|LATEST UPDATE
(FTM/Catalase)
Growth is only seen below the oxygen zone in the FTM tube. This organism doesn't utilize
oxygen for its metabolism it is killed by oxygen. This doesn't have catalase. This organism is
negative for the catalase test.
Which of the following classifications best fits this description?
Obligate (strict) anaerobes
(FTM/catalase)
Growth at the top of the FTM tube only within the oxygen zone only, therefore the organism
requires oxygen for growth. This organism uses an electron transport chain with oxygen as the
final electron acceptor. This organism also requires the enzyme catalase to protect it from toxic
forms of oxygen. This organism is positive for the catalase test.
Which of the following classifications best fits this description?
Obligate (strict) aerobes
(FTM/catalase)
More growth at the top of the FTM tube in the oxygen zone is seen than in the non-oxygen
zone, therefore the organism can grow better in the presence of oxygen but doesn't require it
for growth. This organism uses an electron transport chain with oxygen as the final electron
1|Page
,acceptor when oxygen is present. This organism also requires the enzyme catalase to protect it
from toxic forms of oxygen. This organism is positive for the catalase test.
Which of the following classifications best fits this description?
Facultative anearobes
(Methyl Red)
What is the pH indicator for this test?
Methyl Red
(Methyl Red)
What color is the medium prior to addition of the pH indicator?
Yellow
(Methyl Red)
What color is the pH indicator in the dropper bottle?
red
(Methyl Red)
After adding two drops of pH indicator to the culture medium, what color indicates that an
organism has caused a significant drop in pH of the medium (below 4.4) due to the prolific
production of acids?
Red
(Methyl Red)
What color indicates that the pH of the culture medium has not dropped below 4.4?
yellow
(Methyl Red)
Can a Methyl-Red Negative organism cause the pH of the MR-VP culture medium to drop at all
from its initial value?
yes
2|Page
, (Methyl Red)
Would you expect a Methyl-Red positive organism to be Phenol-Red positive for acid
production?
yes
(Methyl Red)
Does a Phenol-Red+ organism have to be Methyl-Red+?
no
Red color after adding pH indicator, organims produced multiple acids from the fermentation of
glucose that dropped the pH to 4.4 or below
positive for acid fermenation
yellow color after adding pH indicator, organism didn't produce multiple acids form the
frementation of glucose pH is 4.5 or above
negative for mixed acid fermenation
(Voges-Proskauer)
What is Barritt's Reagent A?
alpha-naphthol
(Voges-Proskauer)
How many drops did you add of Reagent A?
15
(Voges-Proskauer)
What is Barritt's Reagent B?
potassium hydroxide (KOH)
Voges-Proskauer)
How many drops did you add of Reagent B?
5
3|Page
