2025-2026 SERIES
MICROBIOLOGY LAB FINAL EXAM COMPLETE
QUESTIONS AND CORRECT ANSWERS | GRADED
AND THE LATEST SERIES
Which staining technique is used to determine the thickness of the peptidoglycan
layer based on the cell wall composition?
Ans: Gram stain
Question: Where would you properly dispose of the following items?
Ans: Contaminated slides: Slide trays on student benches
Pipettes: Nalgene buckets on student benches
Used test tubes: Trash cart at front of lab
Uncontaminated broken glass: Broken glass box at front of lab (and notify the TA!)
Question: When are open toed-shoes and shorts allowed in the microbiology
labs?
Ans: Never
Question: What do you use to clean the ocular lenses and objective lenses on
your microscope?
Ans: Lens cleaner and lens paper
, 2025-2026 SERIES
Question: ________________________ microscopy is used to view dead,
stained microorganisms, and ________________________ microscopy is used to
view live, unstained microorganisms
Ans: Brightfield, phase-contrast
Question: What is the purpose of isolation streaks on your environmental
isolate?
Ans: To purify one species of bacteria
Question: In microscopy, what are the three main factors to obtain a good
image?
Ans: Magnification, resolution, and contrast
Question: Which objective lens is used with immersion oil?
Ans: 100X objective lens
Question: When you first enter the lab and again before you leave the lab,
what are two things that you should always do?
Ans: Wash your hands and wipe down the lab bench with QT solution
Question: In Exercise 1 Part 2 Phase-Contrast Microscopy, ______________
______________ was used to visualize bacteria at 1000x total magnification
with oil immersion.
, 2025-2026 SERIES
Ans: Bacillus megaterium
Question: Which of the following is a growth streak?
Ans: perfect up down streak
Question: ______________ ______________ is the positive control organism
for the capsule stain.
Ans: Klebsiella pneumoniae
Question: With regard to staining techniques used in this lab, what is the
definition of a control organism?
Ans: A control organism is known to have a positive or negative result for a
specific staining technique and is used as a comparison to determine the staining
result of an unknown bacteria
Question: When differentially staining bacterial cells, what is the purpose of the
steaming step?
Ans: Endospore stain: Drives the primary stain into keratin proteins
Capsule stain: The steaming step is not used in this staining technique
Gram stain: The steaming step is not used in this staining technique
Question: Based on the following image, where is the appropriate place to
label a Petri plate?
MICROBIOLOGY LAB FINAL EXAM COMPLETE
QUESTIONS AND CORRECT ANSWERS | GRADED
AND THE LATEST SERIES
Which staining technique is used to determine the thickness of the peptidoglycan
layer based on the cell wall composition?
Ans: Gram stain
Question: Where would you properly dispose of the following items?
Ans: Contaminated slides: Slide trays on student benches
Pipettes: Nalgene buckets on student benches
Used test tubes: Trash cart at front of lab
Uncontaminated broken glass: Broken glass box at front of lab (and notify the TA!)
Question: When are open toed-shoes and shorts allowed in the microbiology
labs?
Ans: Never
Question: What do you use to clean the ocular lenses and objective lenses on
your microscope?
Ans: Lens cleaner and lens paper
, 2025-2026 SERIES
Question: ________________________ microscopy is used to view dead,
stained microorganisms, and ________________________ microscopy is used to
view live, unstained microorganisms
Ans: Brightfield, phase-contrast
Question: What is the purpose of isolation streaks on your environmental
isolate?
Ans: To purify one species of bacteria
Question: In microscopy, what are the three main factors to obtain a good
image?
Ans: Magnification, resolution, and contrast
Question: Which objective lens is used with immersion oil?
Ans: 100X objective lens
Question: When you first enter the lab and again before you leave the lab,
what are two things that you should always do?
Ans: Wash your hands and wipe down the lab bench with QT solution
Question: In Exercise 1 Part 2 Phase-Contrast Microscopy, ______________
______________ was used to visualize bacteria at 1000x total magnification
with oil immersion.
, 2025-2026 SERIES
Ans: Bacillus megaterium
Question: Which of the following is a growth streak?
Ans: perfect up down streak
Question: ______________ ______________ is the positive control organism
for the capsule stain.
Ans: Klebsiella pneumoniae
Question: With regard to staining techniques used in this lab, what is the
definition of a control organism?
Ans: A control organism is known to have a positive or negative result for a
specific staining technique and is used as a comparison to determine the staining
result of an unknown bacteria
Question: When differentially staining bacterial cells, what is the purpose of the
steaming step?
Ans: Endospore stain: Drives the primary stain into keratin proteins
Capsule stain: The steaming step is not used in this staining technique
Gram stain: The steaming step is not used in this staining technique
Question: Based on the following image, where is the appropriate place to
label a Petri plate?
