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Portage Microbiology BIOD171 Exam 5
Questions and Answers
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.
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
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?
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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.
A facultative anaerobe is a microorganism capable of growth
under what conditions?
Ans: A facultative anaerobe is capable of growth under aerobic (with
oxygen) and anaerobic (without oxygen) conditions.
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.
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.
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.
The distinctions for Lancefield subgroupings lie in its: (select all
that apply)
Catalase activity
© 2025 All rights reserved
Portage Microbiology BIOD171 Exam 5
Questions and Answers
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.
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
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?
© 2025 All rights reserved
, 2 | Page
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.
A facultative anaerobe is a microorganism capable of growth
under what conditions?
Ans: A facultative anaerobe is capable of growth under aerobic (with
oxygen) and anaerobic (without oxygen) conditions.
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.
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.
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.
The distinctions for Lancefield subgroupings lie in its: (select all
that apply)
Catalase activity
© 2025 All rights reserved
