MICROBIOLOGY LAB FINAL EXAM VERSION
3 2025/2026 WITH ACTUAL CORRECT
QUESTIONS AND VERIFIED DETAILED
ANSWERS |FREQUENTLY TESTED
QUESTIONS AND SOLUTIONS |ALREADY
GRADED A+|NEWEST|BRAND NEW
VERSION!!|LATEST UPDATE
To make a [b] plate, a diluted sample is mixed with molten agar in an empty Petri plate. Bacteria
grow on the surface of the agar plate and grow within the agar.
pour
______________ ______________ is the negative control organism for the Gram stain.
Escherichia coli
Acid-fast staining is used to identify bacteria with a waxy substance called
_____________________ in their cell walls.
Mycolic acid
Match each value with the correct scientific notation format.
0.348 X 106 CFU/g: 3.48 X 105 CFU/g
267 X 107 CFU/g: 2.67 X 109 CFU/g
95.1 X 108 CFU/g: 9.51 X 109 CFU/g
What does a positive casein hydrolysis test mean?
The unknown environmental isolate can break down milk protein
If you start with one copy of DNA and run PCR for 10 cycles, how many copies will you have at
the end?
1,024 copies
What indicates a positive catalase test?
1|Page
, The presence of gas bubbles
Which of the following shows a positive result for the casein hydrolysis test?
clear zone - subtilis
Observations of colony morphology, cell morphology, and Gram stain reaction will provide
enough data to identify the genus and species of your unknown environmental isolate.
False
A viable plate count assay is an example of an indirect counting method for enumerating
bacteria.
True
What are the three steps in one cycle of PCR?
Step 1: Denaturation
Step 2: Annealing
Step 3: Extension
In the molecular identification exercise, what is the purpose of PCR?
To make lots of copies of the 16S gene of your unknown environmental isolate
What were the final dilutions of the spread plates in the bacterial enumeration exercise?
10-3 through 10-6
What does the formation of a dark precipitate in the Kligler's test mean?
Positive for production of hydrogen sulfide
PCR stands for ______________ ______________ ______________ .
polymerase chain reaction
For the acid-fast staining technique, [A] is the positive control organism, and [B] is the negative
control organism.
Mycobacterium smegmatis
Staphylococcus epidermidis
What will happen to the number of T4 phage particles present in a sample after all of the
Escherichia coli cells have been lysed?
2|Page
3 2025/2026 WITH ACTUAL CORRECT
QUESTIONS AND VERIFIED DETAILED
ANSWERS |FREQUENTLY TESTED
QUESTIONS AND SOLUTIONS |ALREADY
GRADED A+|NEWEST|BRAND NEW
VERSION!!|LATEST UPDATE
To make a [b] plate, a diluted sample is mixed with molten agar in an empty Petri plate. Bacteria
grow on the surface of the agar plate and grow within the agar.
pour
______________ ______________ is the negative control organism for the Gram stain.
Escherichia coli
Acid-fast staining is used to identify bacteria with a waxy substance called
_____________________ in their cell walls.
Mycolic acid
Match each value with the correct scientific notation format.
0.348 X 106 CFU/g: 3.48 X 105 CFU/g
267 X 107 CFU/g: 2.67 X 109 CFU/g
95.1 X 108 CFU/g: 9.51 X 109 CFU/g
What does a positive casein hydrolysis test mean?
The unknown environmental isolate can break down milk protein
If you start with one copy of DNA and run PCR for 10 cycles, how many copies will you have at
the end?
1,024 copies
What indicates a positive catalase test?
1|Page
, The presence of gas bubbles
Which of the following shows a positive result for the casein hydrolysis test?
clear zone - subtilis
Observations of colony morphology, cell morphology, and Gram stain reaction will provide
enough data to identify the genus and species of your unknown environmental isolate.
False
A viable plate count assay is an example of an indirect counting method for enumerating
bacteria.
True
What are the three steps in one cycle of PCR?
Step 1: Denaturation
Step 2: Annealing
Step 3: Extension
In the molecular identification exercise, what is the purpose of PCR?
To make lots of copies of the 16S gene of your unknown environmental isolate
What were the final dilutions of the spread plates in the bacterial enumeration exercise?
10-3 through 10-6
What does the formation of a dark precipitate in the Kligler's test mean?
Positive for production of hydrogen sulfide
PCR stands for ______________ ______________ ______________ .
polymerase chain reaction
For the acid-fast staining technique, [A] is the positive control organism, and [B] is the negative
control organism.
Mycobacterium smegmatis
Staphylococcus epidermidis
What will happen to the number of T4 phage particles present in a sample after all of the
Escherichia coli cells have been lysed?
2|Page
