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Portage Microbiology BIOD171 Exam 5
Questions and Answers (Expert Solutions)
Q: Define the concept of universal precautions.
ANS 🗹🗹: Universal precautions means any and all samples, whether known or
unknown, are to be treated as potentially hazardous (or pathogenic) materials.
Q: List at least 3 observations a researcher would be sure to note while assessing an
unknown microbial sample.
ANS 🗹🗹: A lab researcher would be certain to note:
Size and shape
Any observable motility
Gram status (positive or negative)
The presence of any chemical reactions
Changes in color localized to the organism or the surrounding media
Capture (or draw) images of any of the characteristics described above
Q: While observing an unknown sample of limited amounts, a researcher must determine
the following observations: (1) the presence of any motility and (2) its Gram status using
the same sample—the liquid sample cannot be divided. Which would you determine first
and why?
ANS 🗹🗹: 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. The correct approach
would be to place the liquid culture on a glass slide and determine its motility
status. Next, the same liquid culture can be heat fixed and Gram stained.
Q: A facultative anaerobe is a microorganism capable of growth under what conditions?
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ANS 🗹🗹: A facultative anaerobe is capable of growth under aerobic (with oxygen)
and anaerobic (without oxygen) conditions.
Q: As Streptococcus is catalase negative would it thrive or die in the presence of
peroxides? Why?
ANS 🗹🗹: Streptococcus is catalse negative which means it cannot break down
peroxides and if any peroxides are present it would die.
Q: Streptococcus is most often streaked onto:
ANS 🗹🗹: Blood agar
Strep is often cultured on Blood agar plates to determine its hemolytic properties,
which aids in the classification (and differentiation) process.
Q: True or False. The Lancefield groups are used to subdivide antigenic groups of gamma-
hemolytic Streptococcus.
ANS 🗹🗹: False
The Lancefield groupings are used to subdivide beta-hemolytic Strep.
Q: The distinctions for Lancefield subgroupings lie in its: (select all that apply)
Catalase activity
Hemolytic activity
Carbohydrate composition of antigens
All of the above
ANS 🗹🗹: Carbohydrate composition of antigens
Carbohydrate composition of antigens present in the cell wall determines the
Lancefield groupings (A, B, C, etc). Note, ALL strep under Lancefield groupings are
Portage Microbiology BIOD171 Exam 5
Questions and Answers (Expert Solutions)
Q: Define the concept of universal precautions.
ANS 🗹🗹: Universal precautions means any and all samples, whether known or
unknown, are to be treated as potentially hazardous (or pathogenic) materials.
Q: List at least 3 observations a researcher would be sure to note while assessing an
unknown microbial sample.
ANS 🗹🗹: A lab researcher would be certain to note:
Size and shape
Any observable motility
Gram status (positive or negative)
The presence of any chemical reactions
Changes in color localized to the organism or the surrounding media
Capture (or draw) images of any of the characteristics described above
Q: While observing an unknown sample of limited amounts, a researcher must determine
the following observations: (1) the presence of any motility and (2) its Gram status using
the same sample—the liquid sample cannot be divided. Which would you determine first
and why?
ANS 🗹🗹: 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. The correct approach
would be to place the liquid culture on a glass slide and determine its motility
status. Next, the same liquid culture can be heat fixed and Gram stained.
Q: A facultative anaerobe is a microorganism capable of growth under what conditions?
, Page | 2
ANS 🗹🗹: A facultative anaerobe is capable of growth under aerobic (with oxygen)
and anaerobic (without oxygen) conditions.
Q: As Streptococcus is catalase negative would it thrive or die in the presence of
peroxides? Why?
ANS 🗹🗹: Streptococcus is catalse negative which means it cannot break down
peroxides and if any peroxides are present it would die.
Q: Streptococcus is most often streaked onto:
ANS 🗹🗹: Blood agar
Strep is often cultured on Blood agar plates to determine its hemolytic properties,
which aids in the classification (and differentiation) process.
Q: True or False. The Lancefield groups are used to subdivide antigenic groups of gamma-
hemolytic Streptococcus.
ANS 🗹🗹: False
The Lancefield groupings are used to subdivide beta-hemolytic Strep.
Q: The distinctions for Lancefield subgroupings lie in its: (select all that apply)
Catalase activity
Hemolytic activity
Carbohydrate composition of antigens
All of the above
ANS 🗹🗹: Carbohydrate composition of antigens
Carbohydrate composition of antigens present in the cell wall determines the
Lancefield groupings (A, B, C, etc). Note, ALL strep under Lancefield groupings are
