BIOD 171 Module 5 Exam – Essential
Microbiology (2026/2027 Update)
Portage Learning / Geneva College
1. Define the concept of universal precautions.
*Universal precautions means any and all samples, whether known or
unknown, are to be treated as potentially hazardous (or pathogenic)
materials *
Rationale: Universal precautions require that all biological samples be
handled with equal caution because the infectious status may be unknown.
This protective principle ensures worker and public safety by assuming the
presence of infectious agents in any specimen .
2. List at least 3 observations a researcher would be sure to note while
assessing an unknown microbial sample.
*A researcher would typically record: 1. Size and shape (morphology)
2. Any observable motility 3. Gram status (positive or negative) 4.
Presence of any chemical reactions 5. Color changes localized to the
organism or surrounding media 6. Visual documentation (photos or
drawings) of observations *
Rationale: Systematic observation of morphological characteristics, motility,
and staining properties is essential for preliminary identification of unknown
microorganisms .
,3. While observing an unknown sample of limited amounts, a
researcher must determine motility and Gram status using the same
sample—the liquid cannot be divided. Which would you determine
first and why?
*You must determine motility before determining the Gram status.
Motility requires a wet mount, while Gram staining requires heat
fixing the sample. If one were to begin with the Gram stain, the heat
fixation process would kill the organism, making any observations
regarding motility impossible *
Rationale: The correct approach is to place the liquid culture on a glass slide
and determine motility status first, then heat-fix the same sample for Gram
staining .
4. A facultative anaerobe is a microorganism capable of growth under
what conditions?
*A facultative anaerobe is capable of growth under aerobic (with
oxygen) and anaerobic (without oxygen) conditions *
Rationale: Facultative anaerobes can metabolize energy aerobically when
oxygen is present but can switch to fermentation or anaerobic respiration
when oxygen is absent .
,5. As Streptococcus is catalase negative, would it thrive or die in the
presence of peroxides? Why?
*Streptococcus would not survive in the presence of peroxides—it is
unable to break down peroxides (catalase negative). Left unchecked,
peroxides would damage the cellular integrity of Strep, causing
lysis/cell death *
Rationale: Catalase is the enzyme that breaks down hydrogen peroxide into
water and oxygen. Without it, peroxide accumulates and damages the cell .
6. Streptococcus is most often streaked onto:
A) Chocolate agar
B) Blood agar
C) EMB agar
D) Spirit Blue agar
*B) Blood agar *
Rationale: Strep is often cultured on Blood agar plates to determine its
hemolytic properties (alpha, beta, or gamma hemolysis), which aids in
classification and differentiation .
7. True or False: The Lancefield groups are used to subdivide antigenic
groups of gamma-hemolytic Streptococcus.
*False *
, Rationale: The Lancefield groupings are used to subdivide beta-hemolytic
Streptococcus, not gamma-hemolytic Strep .
8. The distinctions for Lancefield subgroupings lie in its: (Select all that
apply)
A) Hemolytic activity
B) Catalase activity
C) Carbohydrate composition of antigens
D) All of the above
*C) Carbohydrate composition of antigens *
Rationale: Carbohydrate composition of antigens present in the cell wall
determines the Lancefield groupings (A, B, C, etc.). All Strep under Lancefield
groupings are catalase negative and beta-hemolytic .
9. Left untreated, strep throat can progress to ______, which displays
_____ hemolytic activity.
A) Strep. Pharyngitis; alpha
B) Rheumatic fever; beta
C) Strep. Septicemia; gamma
D) Strep. Pharyngitis; beta
*B) Rheumatic fever; beta *
Microbiology (2026/2027 Update)
Portage Learning / Geneva College
1. Define the concept of universal precautions.
*Universal precautions means any and all samples, whether known or
unknown, are to be treated as potentially hazardous (or pathogenic)
materials *
Rationale: Universal precautions require that all biological samples be
handled with equal caution because the infectious status may be unknown.
This protective principle ensures worker and public safety by assuming the
presence of infectious agents in any specimen .
2. List at least 3 observations a researcher would be sure to note while
assessing an unknown microbial sample.
*A researcher would typically record: 1. Size and shape (morphology)
2. Any observable motility 3. Gram status (positive or negative) 4.
Presence of any chemical reactions 5. Color changes localized to the
organism or surrounding media 6. Visual documentation (photos or
drawings) of observations *
Rationale: Systematic observation of morphological characteristics, motility,
and staining properties is essential for preliminary identification of unknown
microorganisms .
,3. While observing an unknown sample of limited amounts, a
researcher must determine motility and Gram status using the same
sample—the liquid cannot be divided. Which would you determine
first and why?
*You must determine motility before determining the Gram status.
Motility requires a wet mount, while Gram staining requires heat
fixing the sample. If one were to begin with the Gram stain, the heat
fixation process would kill the organism, making any observations
regarding motility impossible *
Rationale: The correct approach is to place the liquid culture on a glass slide
and determine motility status first, then heat-fix the same sample for Gram
staining .
4. A facultative anaerobe is a microorganism capable of growth under
what conditions?
*A facultative anaerobe is capable of growth under aerobic (with
oxygen) and anaerobic (without oxygen) conditions *
Rationale: Facultative anaerobes can metabolize energy aerobically when
oxygen is present but can switch to fermentation or anaerobic respiration
when oxygen is absent .
,5. As Streptococcus is catalase negative, would it thrive or die in the
presence of peroxides? Why?
*Streptococcus would not survive in the presence of peroxides—it is
unable to break down peroxides (catalase negative). Left unchecked,
peroxides would damage the cellular integrity of Strep, causing
lysis/cell death *
Rationale: Catalase is the enzyme that breaks down hydrogen peroxide into
water and oxygen. Without it, peroxide accumulates and damages the cell .
6. Streptococcus is most often streaked onto:
A) Chocolate agar
B) Blood agar
C) EMB agar
D) Spirit Blue agar
*B) Blood agar *
Rationale: Strep is often cultured on Blood agar plates to determine its
hemolytic properties (alpha, beta, or gamma hemolysis), which aids in
classification and differentiation .
7. True or False: The Lancefield groups are used to subdivide antigenic
groups of gamma-hemolytic Streptococcus.
*False *
, Rationale: The Lancefield groupings are used to subdivide beta-hemolytic
Streptococcus, not gamma-hemolytic Strep .
8. The distinctions for Lancefield subgroupings lie in its: (Select all that
apply)
A) Hemolytic activity
B) Catalase activity
C) Carbohydrate composition of antigens
D) All of the above
*C) Carbohydrate composition of antigens *
Rationale: Carbohydrate composition of antigens present in the cell wall
determines the Lancefield groupings (A, B, C, etc.). All Strep under Lancefield
groupings are catalase negative and beta-hemolytic .
9. Left untreated, strep throat can progress to ______, which displays
_____ hemolytic activity.
A) Strep. Pharyngitis; alpha
B) Rheumatic fever; beta
C) Strep. Septicemia; gamma
D) Strep. Pharyngitis; beta
*B) Rheumatic fever; beta *
