1|Page
MICROBIOLOGY LAB FINAL EXAM VERSION 3 LATEST 2025/2026
ACTUAL EXAM WITH COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS (100% VERIFIED ANSWERS) |ALREADY
GRADED A+| ||PROFESSOR VERIFIED|| ||BRANDNEW!!!||
Which of the following stains are used to determine the Gram
reaction of bacterial cells? Select all correct answers. - ANSWER-
Safranin
Crystal violet
Match the bacterial species listed below with the correct Gram
reaction. - ANSWER-Bacillus megaterium: Gram positive
Staphylococcus epidermidis: Gram positive
Escherichia coli: Gram negative
Which staining technique is the quickest way to determine the cell
morphology of bacteria? - ANSWER-Simple stain
What is the cellular morphology of spherical-shaped bacterial
cells? - ANSWER-Cocci (or coccus)
,2|Page
What is the definition of an indirect method for enumerating
bacteria? - ANSWER-Estimating the number of bacteria based on
metabolic tests or other growth characteristics
Match each acronym with its meaning. - ANSWER-TNTC: Too
Numerous To Count
NSS: Not Statistically Significant
CFU: Colony Forming Units
What is the acceptable range for counting colonies on plates in
the bacterial enumeration exercise? - ANSWER-30 to 300
colonies per plate
What is the purpose of re-streaking your environmental unknown?
- ANSWER-To isolate a single species of bacteria and to keep it
alive
There are 229 colonies on the 10-5 dilution plate. This is
equivalent to... - ANSWER-2.29 X 107 CFU/g
, 3|Page
What is the definition of a direct method for enumerating bacteria?
- ANSWER-Counting individual bacterial cells
What is the purpose of a serial dilution in a viable plate assay?
Select all correct answers. - ANSWER-The amount of bacteria in
the original sample is unknown, and at least one plate needs to
have a countable number of colonies
The serial dilution allows us to calculate the amount of bacteria in
the original sample
The serial dilution allows bacteria to undergo exponential growth
Bacteria need a liquid medium to reproduce
Match each technique with the category of bacterial enumeration
that it falls under. - ANSWER-Coulter counter: Direct enumeration
Hemocytometer: Direct enumeration
Measurements of dry (or wet) weight (or volume): Indirect
enumeration
Metabolic tests: Indirect enumeration
Spectrophotometer: Indirect enumeration
Viable plate count assay: Indirect enumeration
MICROBIOLOGY LAB FINAL EXAM VERSION 3 LATEST 2025/2026
ACTUAL EXAM WITH COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS (100% VERIFIED ANSWERS) |ALREADY
GRADED A+| ||PROFESSOR VERIFIED|| ||BRANDNEW!!!||
Which of the following stains are used to determine the Gram
reaction of bacterial cells? Select all correct answers. - ANSWER-
Safranin
Crystal violet
Match the bacterial species listed below with the correct Gram
reaction. - ANSWER-Bacillus megaterium: Gram positive
Staphylococcus epidermidis: Gram positive
Escherichia coli: Gram negative
Which staining technique is the quickest way to determine the cell
morphology of bacteria? - ANSWER-Simple stain
What is the cellular morphology of spherical-shaped bacterial
cells? - ANSWER-Cocci (or coccus)
,2|Page
What is the definition of an indirect method for enumerating
bacteria? - ANSWER-Estimating the number of bacteria based on
metabolic tests or other growth characteristics
Match each acronym with its meaning. - ANSWER-TNTC: Too
Numerous To Count
NSS: Not Statistically Significant
CFU: Colony Forming Units
What is the acceptable range for counting colonies on plates in
the bacterial enumeration exercise? - ANSWER-30 to 300
colonies per plate
What is the purpose of re-streaking your environmental unknown?
- ANSWER-To isolate a single species of bacteria and to keep it
alive
There are 229 colonies on the 10-5 dilution plate. This is
equivalent to... - ANSWER-2.29 X 107 CFU/g
, 3|Page
What is the definition of a direct method for enumerating bacteria?
- ANSWER-Counting individual bacterial cells
What is the purpose of a serial dilution in a viable plate assay?
Select all correct answers. - ANSWER-The amount of bacteria in
the original sample is unknown, and at least one plate needs to
have a countable number of colonies
The serial dilution allows us to calculate the amount of bacteria in
the original sample
The serial dilution allows bacteria to undergo exponential growth
Bacteria need a liquid medium to reproduce
Match each technique with the category of bacterial enumeration
that it falls under. - ANSWER-Coulter counter: Direct enumeration
Hemocytometer: Direct enumeration
Measurements of dry (or wet) weight (or volume): Indirect
enumeration
Metabolic tests: Indirect enumeration
Spectrophotometer: Indirect enumeration
Viable plate count assay: Indirect enumeration
