BIOL271: Microbiology w/Lab
2026 – 2027 | Portage Learning
Module 5: Personal Protective Equipment and Pathogenic Microbes
Exam Review | LockDown Browser
By PortageMaster
Question 1
Define the concept of universal precautions.
✓ Answer: All samples, both known and unknown, are treated as if they were potentially
pathogenic.
Feedback: Universal (a.k.a. standard) precautions protect lab personnel from undiagnosed infectious
agents.
Question 2
List at least 3 observations a researcher would be sure to note while assessing an unknown
microbial sample.
✓ Answer: (1) Any motility/movement observed; (2) the Gram status; (3) the size and
shape of the sample.
Feedback: Additional observations: arrangement, color/pigment, biochemical reactions, growth
medium, photo documentation.
Question 3
Observing an unknown sample of limited amount, a researcher must determine (1) presence of
motility and (2) Gram status from the same liquid sample (cannot be divided). Which would you
determine first and why?
✓ Answer: Motility first — observing motility requires a wet mount (live, in liquid). Gram
staining requires heat-fixing, which kills/distorts cells and would make motility
observation impossible afterward.
Feedback: Order matters: any procedure that fixes or kills cells must come after any live-cell
observation.
Question 4
A facultative anaerobe is a microorganism capable of growth under what conditions?
✓ Answer: Under both anaerobic and aerobic conditions.
Feedback: Facultative anaerobes (e.g., E. coli) prefer aerobic respiration but can switch to
fermentation when oxygen is unavailable.
,Question 5
The Lancefield groups are used to subdivide antigenic groups of alpha-hemolytic Streptococcus.
True or False?
• True
• ✓ False
Correct Answer: False
Feedback: Lancefield groups subdivide beta-hemolytic Streptococcus, not alpha-hemolytic.
Question 6
The Lancefield groupings are used to subdivide beta-hemolytic Strep. True or False?
• ✓ True
• False
Correct Answer: True
Feedback: Lancefield grouping (A–V) is based on the carbohydrate composition of cell-wall antigens in
beta-hemolytic streptococci.
Question 7
The distinctions for Lancefield subgroupings lie in its: (select all that apply)
• Catalase activity
• ✓ Carbohydrate composition of antigens
• Hemolytic activity
• All of the above
Correct Answer: Carbohydrate composition of antigens
Feedback: Lancefield groups are defined by the carbohydrate composition of cell-wall antigens.
Question 8
Rheumatic fever displays ______ hemolytic activity and occurs when ______ is left untreated.
• ✓ Beta; Strep. Pharyngitis
• Gamma; Strep. Septicemia
• Beta; Rheumatic fever
• Alpha; Strep. Pharyngitis
Correct Answer: Beta; Strep. Pharyngitis
Feedback: Untreated beta-hemolytic Streptococcus pharyngitis (strep throat) can progress to
rheumatic fever.
, Question 9
Strep throat (strep. pharyngitis) can lead to rheumatic fever if left untreated and displays
beta-hemolytic activity. True or False?
• ✓ True
• False
Correct Answer: True
Feedback: Group A Strep (S. pyogenes) is beta-hemolytic; untreated infection can lead to rheumatic
fever weeks after the acute episode.
Question 10
Under most circumstances, staphylococcus can be found in ~80% of human population where it
remains non-symptomatic. True or False?
• True
• ✓ False
Correct Answer: False
Feedback: Staphylococcus is found asymptomatically in roughly 30% of the human population, not
80%.
Question 11
Staphylococcus is found (non-symptomatic) in ~30% of the human population. True or False?
• ✓ True
• False
Correct Answer: True
Feedback: S. aureus colonizes the nares of ~30% of healthy individuals without causing disease in
most carriers.
Question 12
Define commensal bacteria.
✓ Answer: Bacteria that neither benefit nor harm the host from which they get nutrients.
Feedback: Compare with mutualism (both benefit) and parasitism (pathogen benefits, host harmed).
Question 13
How can Staphylococcus be differentially tested?
✓ Answer: Staphylococcus can grow in the presence of bile salts (and high salt — e.g.,
MSA, 7.5% NaCl).
Feedback: MSA (Mannitol Salt Agar) is the classic selective + differential plate for staphylococci.
2026 – 2027 | Portage Learning
Module 5: Personal Protective Equipment and Pathogenic Microbes
Exam Review | LockDown Browser
By PortageMaster
Question 1
Define the concept of universal precautions.
✓ Answer: All samples, both known and unknown, are treated as if they were potentially
pathogenic.
Feedback: Universal (a.k.a. standard) precautions protect lab personnel from undiagnosed infectious
agents.
Question 2
List at least 3 observations a researcher would be sure to note while assessing an unknown
microbial sample.
✓ Answer: (1) Any motility/movement observed; (2) the Gram status; (3) the size and
shape of the sample.
Feedback: Additional observations: arrangement, color/pigment, biochemical reactions, growth
medium, photo documentation.
Question 3
Observing an unknown sample of limited amount, a researcher must determine (1) presence of
motility and (2) Gram status from the same liquid sample (cannot be divided). Which would you
determine first and why?
✓ Answer: Motility first — observing motility requires a wet mount (live, in liquid). Gram
staining requires heat-fixing, which kills/distorts cells and would make motility
observation impossible afterward.
Feedback: Order matters: any procedure that fixes or kills cells must come after any live-cell
observation.
Question 4
A facultative anaerobe is a microorganism capable of growth under what conditions?
✓ Answer: Under both anaerobic and aerobic conditions.
Feedback: Facultative anaerobes (e.g., E. coli) prefer aerobic respiration but can switch to
fermentation when oxygen is unavailable.
,Question 5
The Lancefield groups are used to subdivide antigenic groups of alpha-hemolytic Streptococcus.
True or False?
• True
• ✓ False
Correct Answer: False
Feedback: Lancefield groups subdivide beta-hemolytic Streptococcus, not alpha-hemolytic.
Question 6
The Lancefield groupings are used to subdivide beta-hemolytic Strep. True or False?
• ✓ True
• False
Correct Answer: True
Feedback: Lancefield grouping (A–V) is based on the carbohydrate composition of cell-wall antigens in
beta-hemolytic streptococci.
Question 7
The distinctions for Lancefield subgroupings lie in its: (select all that apply)
• Catalase activity
• ✓ Carbohydrate composition of antigens
• Hemolytic activity
• All of the above
Correct Answer: Carbohydrate composition of antigens
Feedback: Lancefield groups are defined by the carbohydrate composition of cell-wall antigens.
Question 8
Rheumatic fever displays ______ hemolytic activity and occurs when ______ is left untreated.
• ✓ Beta; Strep. Pharyngitis
• Gamma; Strep. Septicemia
• Beta; Rheumatic fever
• Alpha; Strep. Pharyngitis
Correct Answer: Beta; Strep. Pharyngitis
Feedback: Untreated beta-hemolytic Streptococcus pharyngitis (strep throat) can progress to
rheumatic fever.
, Question 9
Strep throat (strep. pharyngitis) can lead to rheumatic fever if left untreated and displays
beta-hemolytic activity. True or False?
• ✓ True
• False
Correct Answer: True
Feedback: Group A Strep (S. pyogenes) is beta-hemolytic; untreated infection can lead to rheumatic
fever weeks after the acute episode.
Question 10
Under most circumstances, staphylococcus can be found in ~80% of human population where it
remains non-symptomatic. True or False?
• True
• ✓ False
Correct Answer: False
Feedback: Staphylococcus is found asymptomatically in roughly 30% of the human population, not
80%.
Question 11
Staphylococcus is found (non-symptomatic) in ~30% of the human population. True or False?
• ✓ True
• False
Correct Answer: True
Feedback: S. aureus colonizes the nares of ~30% of healthy individuals without causing disease in
most carriers.
Question 12
Define commensal bacteria.
✓ Answer: Bacteria that neither benefit nor harm the host from which they get nutrients.
Feedback: Compare with mutualism (both benefit) and parasitism (pathogen benefits, host harmed).
Question 13
How can Staphylococcus be differentially tested?
✓ Answer: Staphylococcus can grow in the presence of bile salts (and high salt — e.g.,
MSA, 7.5% NaCl).
Feedback: MSA (Mannitol Salt Agar) is the classic selective + differential plate for staphylococci.
