BIOD 171 MICROBIOLOGY MODULE 5
EXAM QUESTIONS AND ANSWERS
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.
2. List at least 3 observations a researcher would be sure to note while
assessing an unknown microbial sample.: 1. size and shape
2. gram status
3. any observable motility
3. 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?: You would need to determine the motility first and then the Gram status.
Motility requires a wet mount and Gram staining requires heat fixing the sample. If you perform a Gram
stain first the heat fixation would kill the organism, making it impossible to observe motility.
4. A facultative anaerobe is a microorganism capable of growth
under what conditions?: It is capable of growth under both anaerobic and aerobic
conditions
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, 5. As Streptococcus is catalase negative would it thrive or die in the
presence of peroxides? Why?: It would die. Because it is catalase negative it wouldn't be
able to breakdown peroxides.
6. Streptococcus is most often streaked onto:
- Chocolate agar
- EMB agar
- Blood agar
- Spirit Blue agar: Blood agar
Strep is often cultured on Blood agar plates to determine its hemolytic properties, which aids in the
classification (and ditterentiation) process.
7. True or False. The Lancefield groups are used to subdivide
antigenic groups of gamma-hemolytic Streptococcus.: False
The Lancefield groupings are used to subdivide beta-hemolytic Strep
8. Greater than 90% of all human streptococcal infections belong to:
- Group C
- Group B
- Group A
- Group D: Group A
2/
12
EXAM QUESTIONS AND ANSWERS
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.
2. List at least 3 observations a researcher would be sure to note while
assessing an unknown microbial sample.: 1. size and shape
2. gram status
3. any observable motility
3. 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?: You would need to determine the motility first and then the Gram status.
Motility requires a wet mount and Gram staining requires heat fixing the sample. If you perform a Gram
stain first the heat fixation would kill the organism, making it impossible to observe motility.
4. A facultative anaerobe is a microorganism capable of growth
under what conditions?: It is capable of growth under both anaerobic and aerobic
conditions
1/
12
, 5. As Streptococcus is catalase negative would it thrive or die in the
presence of peroxides? Why?: It would die. Because it is catalase negative it wouldn't be
able to breakdown peroxides.
6. Streptococcus is most often streaked onto:
- Chocolate agar
- EMB agar
- Blood agar
- Spirit Blue agar: Blood agar
Strep is often cultured on Blood agar plates to determine its hemolytic properties, which aids in the
classification (and ditterentiation) process.
7. True or False. The Lancefield groups are used to subdivide
antigenic groups of gamma-hemolytic Streptococcus.: False
The Lancefield groupings are used to subdivide beta-hemolytic Strep
8. Greater than 90% of all human streptococcal infections belong to:
- Group C
- Group B
- Group A
- Group D: Group A
2/
12
