BIOD 171 Microbiology Module 5 Exam (Portage
Learning) Updated Questions and Answers
(2026/2027) | Practice Review | A+ Verified
• What would a researcher be certain to note while analyzing a microbial sample?
-✓✓1. Size and shape
2. Any observable motility
3. Gram status (positive or negative)
4. The presence of any chemical reactions
5. Changes in color localized to the organism or the surrounding media
6. Capture (or draw) images of any of the characteristics described above
• Which non-selective yet differential agar plate should be used if a Streptococcus
sample is suspected? -✓✓A BAP (blood agar plate) would be the quickest way to
identify and classify a potential streptococcus microbe based on its hemolytic
properties.
• What disease can result if a patient with streptococcal pharyngitis goes untreated?
-✓✓Rheumatic fever occurs in approximately 3% of untreated cases of
streptococcal pharyngitis, presenting approximately 2-3 weeks post-infection.
• Streptococcus, E. coli, pseudomonas, and klebsiella are all capable of causing
what disease? -✓✓All of the above foreign microbes are capable of causing
septicemia, also known as blood poisoning.
• What is a facultative anaerobe? -✓✓A facultative anaerobe is capable of growth
under both aerobic (with oxygen) and anaerobic (in the absence of oxygen)
condition.
,• How can Staphylococcus be differentially tested? -✓✓Staphylococcus species
are capable of growth in the presence of bile salts.
• A bacterial swab is taken from a patient with impetigo and streaked across an
MSA plate. Following incubation at 37C, what will be the color of the agar? -
✓✓The causative agent of impetigo is staph aureus, a Gram-positive bacterium
capable of fermenting mannitol. Fermentation will lower the pH of the agar and
change the dye color from red to yellow.
• If a patient were suspected to have tuberculosis (TB), which differential stain
would you select and why? -✓✓To stain for TB, one would utilize an acid-fast
stain to best visual the foreign microbe. As a mycobacterium tuberculosis would
stain poorly (indeterminate) using the Gram stain.
• According to the module, which mycobacterium infection will be treated free of
charge by the World Health Organization (WHO)? -✓✓Leprosy is completely
curable using a multiple-drug therapy regimen consisting of various combinations
of the drugs dapsone, rifampin and clofazimine—all of which is given free of
charge.
• What are the three main conditions caused by the botulism toxin? -
✓✓Foodborne, infant and wound. Foodborne botulism is often the result of
improperly canned, contaminated, low-acidic foods such as green beans, corn and
beats. Infant botulism occurs when children, usually under the age of 6 months
consume foods containing the bacteria. A potential source of infant botulism is
honey (which is why pediatricians recommend avoiding feeding honey to infants)
but can also be found in common places such as soil. Wound botulism occurs when
C. botulinum bacteria colonize a deep wound, often a puncture such as those who
inject street drugs such as heroine. As contaminated needles are injected through
the skin, spores enter the body and, in the absence of oxygen, release the toxin.
, • Why are infants (< 6 months) more susceptible to botulism? -✓✓Due to infants
still maturing intestinal tract and lack of an adult microbiota, the bacteria are able
to colonize and produce the associated toxin. In adults, only the direct ingestion of
the pre-formed toxin causes disease—ingestion of C. botulinum or the associated
spores do not cause illness as a mature intestinal microbiota sufficiently prevents
bacterial germination and growth.
• What is the mechanism of action of the toxin produced by clostridium tentani
(tetanus)? -✓✓The toxin acts on inhibitory neurons causing systemic muscle
stiffness and spasms. Muscle stiffness can be observed in the jaw (lock-jaw) or
spread systemically (if left untreated) to muscles relating to respiratory function.
• What Gram-negative bacterium might you come into contact with in a unsanitary
hot tub? -✓✓Legionella is often associated with unclean water systems such as hot
tubs, hot water tanks and AC units. Notably, legionella can only be transmitted
through water droplets small enough to be inhaled.
• What are the three forms of plague, and what regions do they affect? -
✓✓Bubonic (lymph), pneumonic (lungs) and septicemic (blood). Bubonic plague
is best characterized by painfully swollen lymph nodes. Pneumonic plague affects
the respiratory system (lungs). The most rare of all three plagues, septicemic
plague targets the blood system and, if left untreated, will develop into a life-
threatening illness as the blood-borne bacteria can infect all major organs.
• According to the module, which STD might be best identified via dark-field
microscopy? -✓✓Syphilis. The causative agent, treponema pallidum, is a thin
spirochete, making Gram staining (and visualization) difficult. Treponema is
therefore most often best identified via dark-field microscopy.
• Streptococcal Pharyngitis (Strep Throat) -✓✓Streptococcus
Learning) Updated Questions and Answers
(2026/2027) | Practice Review | A+ Verified
• What would a researcher be certain to note while analyzing a microbial sample?
-✓✓1. Size and shape
2. Any observable motility
3. Gram status (positive or negative)
4. The presence of any chemical reactions
5. Changes in color localized to the organism or the surrounding media
6. Capture (or draw) images of any of the characteristics described above
• Which non-selective yet differential agar plate should be used if a Streptococcus
sample is suspected? -✓✓A BAP (blood agar plate) would be the quickest way to
identify and classify a potential streptococcus microbe based on its hemolytic
properties.
• What disease can result if a patient with streptococcal pharyngitis goes untreated?
-✓✓Rheumatic fever occurs in approximately 3% of untreated cases of
streptococcal pharyngitis, presenting approximately 2-3 weeks post-infection.
• Streptococcus, E. coli, pseudomonas, and klebsiella are all capable of causing
what disease? -✓✓All of the above foreign microbes are capable of causing
septicemia, also known as blood poisoning.
• What is a facultative anaerobe? -✓✓A facultative anaerobe is capable of growth
under both aerobic (with oxygen) and anaerobic (in the absence of oxygen)
condition.
,• How can Staphylococcus be differentially tested? -✓✓Staphylococcus species
are capable of growth in the presence of bile salts.
• A bacterial swab is taken from a patient with impetigo and streaked across an
MSA plate. Following incubation at 37C, what will be the color of the agar? -
✓✓The causative agent of impetigo is staph aureus, a Gram-positive bacterium
capable of fermenting mannitol. Fermentation will lower the pH of the agar and
change the dye color from red to yellow.
• If a patient were suspected to have tuberculosis (TB), which differential stain
would you select and why? -✓✓To stain for TB, one would utilize an acid-fast
stain to best visual the foreign microbe. As a mycobacterium tuberculosis would
stain poorly (indeterminate) using the Gram stain.
• According to the module, which mycobacterium infection will be treated free of
charge by the World Health Organization (WHO)? -✓✓Leprosy is completely
curable using a multiple-drug therapy regimen consisting of various combinations
of the drugs dapsone, rifampin and clofazimine—all of which is given free of
charge.
• What are the three main conditions caused by the botulism toxin? -
✓✓Foodborne, infant and wound. Foodborne botulism is often the result of
improperly canned, contaminated, low-acidic foods such as green beans, corn and
beats. Infant botulism occurs when children, usually under the age of 6 months
consume foods containing the bacteria. A potential source of infant botulism is
honey (which is why pediatricians recommend avoiding feeding honey to infants)
but can also be found in common places such as soil. Wound botulism occurs when
C. botulinum bacteria colonize a deep wound, often a puncture such as those who
inject street drugs such as heroine. As contaminated needles are injected through
the skin, spores enter the body and, in the absence of oxygen, release the toxin.
, • Why are infants (< 6 months) more susceptible to botulism? -✓✓Due to infants
still maturing intestinal tract and lack of an adult microbiota, the bacteria are able
to colonize and produce the associated toxin. In adults, only the direct ingestion of
the pre-formed toxin causes disease—ingestion of C. botulinum or the associated
spores do not cause illness as a mature intestinal microbiota sufficiently prevents
bacterial germination and growth.
• What is the mechanism of action of the toxin produced by clostridium tentani
(tetanus)? -✓✓The toxin acts on inhibitory neurons causing systemic muscle
stiffness and spasms. Muscle stiffness can be observed in the jaw (lock-jaw) or
spread systemically (if left untreated) to muscles relating to respiratory function.
• What Gram-negative bacterium might you come into contact with in a unsanitary
hot tub? -✓✓Legionella is often associated with unclean water systems such as hot
tubs, hot water tanks and AC units. Notably, legionella can only be transmitted
through water droplets small enough to be inhaled.
• What are the three forms of plague, and what regions do they affect? -
✓✓Bubonic (lymph), pneumonic (lungs) and septicemic (blood). Bubonic plague
is best characterized by painfully swollen lymph nodes. Pneumonic plague affects
the respiratory system (lungs). The most rare of all three plagues, septicemic
plague targets the blood system and, if left untreated, will develop into a life-
threatening illness as the blood-borne bacteria can infect all major organs.
• According to the module, which STD might be best identified via dark-field
microscopy? -✓✓Syphilis. The causative agent, treponema pallidum, is a thin
spirochete, making Gram staining (and visualization) difficult. Treponema is
therefore most often best identified via dark-field microscopy.
• Streptococcal Pharyngitis (Strep Throat) -✓✓Streptococcus
