WGU D311 MICROBIOLOGY FINAL EXAM
2025/2026 | COMPLETE QUESTIONS AND
ANSWERS WITH RATIONALES | 100%
VERIFIED/ GRADED A+< RECENT UPDATE>
1. When would it be best to treat a patient with a narrow-spectrum
antimicrobial rather than a broad-spectrum antimicrobial? -
ANSWER When the infectious agent has been identified as a gram-
negative bacterium
2. When can narrow-spectrum antibiotics be used to treat infectious diseases
effectively? - ANSWER When the infection is known to be caused by a
gram-positive bacterium
3. Why is ergosterol targeted by antifungals? - ANSWER Ergosterol
synthesis allows for selective toxicity that is not possible with cholesterol.
4. Which class of cells most often contain extrachromosomal DNA found in
plasmids? - ANSWER Prokaryotic
5. What is the significance of the molecule that makes up the bilayer formed in
the plasma membrane of most bacterial and eukaryotic cells? -
ANSWER Phospholipids help maintain hydrophobic and hydrophilic
environments.
,6. Which microorganisms produce dermatophytes that can cause skin
infections, such as athlete's foot and ringworm? - ANSWER Fungi
7. Which microorganisms can produce human pathogens that spread via
microsporidia? - ANSWER Fungi
8. Why are archaea considered prokaryotic organisms? - ANSWER Their
cells do not contain a nucleus.
9. Why is MRSA more pathogenic than other strains of Staphylococcus
aureus? - ANSWER MRSA has increased antibiotic resistance.
10.A patient recently had an outpatient surgical procedure. After a few days at
home, they noticed swelling and redness at their incision site. How would
this infection be classified? - ANSWER Iatrogenic
11.Which viral virulence factor requires adjustments to the influenza vaccine
annually? - ANSWER Antigenic variation
12.Which pair of enzymes are produced by some bacteria that causes the
clotting of blood to protect the bacteria in the bloodstream, then a digestion
of the clots to allow the bacteria to spread? - ANSWER Coagulase and
kinase
13.How does coinfection of a single cell by multiple strains of a virus increase
it's pathogenicity? - ANSWER Coinfection provides the opportunity for
an antigenic shift.
,14.Canned food is heated and sealed in sterile containers to provide a longer
shelf life and prevent spoilage. Improper canning results in the growth of
microorganisms, which may result in food containers that swell and explode.
15.Which staining technique can be used to identify these microorganisms? -
ANSWER Endospore staining
16.A student in a lab has just completed an endospore stain of Bacillus anthracis
and realized that heat was not applied during the staining technique.
17.What will the student see upon microscopic examination of the slide? -
ANSWER Pink vegetative cells with clear round areas.
18.A physician is given a vaginal swab in order to test for post-antibiotic
vaginal infection.
19.Which microscopic technique would identify opportunistic fungal pathogen?
- ANSWER Wet mount stain
20.A technician has just performed a Gram stain but forgot to add the safranin.
21.What is the likely result of this when viewed microscopically? -
ANSWER Gram-negative organisms can not be seen under the
microscope.
, 22.Which characteristic of mycobacterium makes a Gram stain unsuitable? -
ANSWER The cell wall has a waxy lipid.
23.Which feature of infection indicates the presence of a primary pathogen
rather than an opportunistic pathogen? - ANSWER Patients with healthy
immune systems.
24.After oral antibiotic therapy, a patient is diagnosed with vaginitis.
25.What type of microbe could be causing this opportunistic infection? -
ANSWER Fungus
26.What type of microbe is used to deliver gene therapies to human cells? -
ANSWER Virus
27.What type of diseases are found in higher numbers than expected in local
populations? - ANSWER Epidemic
28.Which describes a mutualistic relationship? - ANSWER Ruminococcus
species using nutrients from a cow's diet to digest plant cellulose in the
rumen.
29.Why are photosynthetic bacteria and algae important to the carbon cycle on
Earth? - ANSWER Photosynthetic microbes metabolize carbon dioxide,
fix carbon, and produce oxygen.
2025/2026 | COMPLETE QUESTIONS AND
ANSWERS WITH RATIONALES | 100%
VERIFIED/ GRADED A+< RECENT UPDATE>
1. When would it be best to treat a patient with a narrow-spectrum
antimicrobial rather than a broad-spectrum antimicrobial? -
ANSWER When the infectious agent has been identified as a gram-
negative bacterium
2. When can narrow-spectrum antibiotics be used to treat infectious diseases
effectively? - ANSWER When the infection is known to be caused by a
gram-positive bacterium
3. Why is ergosterol targeted by antifungals? - ANSWER Ergosterol
synthesis allows for selective toxicity that is not possible with cholesterol.
4. Which class of cells most often contain extrachromosomal DNA found in
plasmids? - ANSWER Prokaryotic
5. What is the significance of the molecule that makes up the bilayer formed in
the plasma membrane of most bacterial and eukaryotic cells? -
ANSWER Phospholipids help maintain hydrophobic and hydrophilic
environments.
,6. Which microorganisms produce dermatophytes that can cause skin
infections, such as athlete's foot and ringworm? - ANSWER Fungi
7. Which microorganisms can produce human pathogens that spread via
microsporidia? - ANSWER Fungi
8. Why are archaea considered prokaryotic organisms? - ANSWER Their
cells do not contain a nucleus.
9. Why is MRSA more pathogenic than other strains of Staphylococcus
aureus? - ANSWER MRSA has increased antibiotic resistance.
10.A patient recently had an outpatient surgical procedure. After a few days at
home, they noticed swelling and redness at their incision site. How would
this infection be classified? - ANSWER Iatrogenic
11.Which viral virulence factor requires adjustments to the influenza vaccine
annually? - ANSWER Antigenic variation
12.Which pair of enzymes are produced by some bacteria that causes the
clotting of blood to protect the bacteria in the bloodstream, then a digestion
of the clots to allow the bacteria to spread? - ANSWER Coagulase and
kinase
13.How does coinfection of a single cell by multiple strains of a virus increase
it's pathogenicity? - ANSWER Coinfection provides the opportunity for
an antigenic shift.
,14.Canned food is heated and sealed in sterile containers to provide a longer
shelf life and prevent spoilage. Improper canning results in the growth of
microorganisms, which may result in food containers that swell and explode.
15.Which staining technique can be used to identify these microorganisms? -
ANSWER Endospore staining
16.A student in a lab has just completed an endospore stain of Bacillus anthracis
and realized that heat was not applied during the staining technique.
17.What will the student see upon microscopic examination of the slide? -
ANSWER Pink vegetative cells with clear round areas.
18.A physician is given a vaginal swab in order to test for post-antibiotic
vaginal infection.
19.Which microscopic technique would identify opportunistic fungal pathogen?
- ANSWER Wet mount stain
20.A technician has just performed a Gram stain but forgot to add the safranin.
21.What is the likely result of this when viewed microscopically? -
ANSWER Gram-negative organisms can not be seen under the
microscope.
, 22.Which characteristic of mycobacterium makes a Gram stain unsuitable? -
ANSWER The cell wall has a waxy lipid.
23.Which feature of infection indicates the presence of a primary pathogen
rather than an opportunistic pathogen? - ANSWER Patients with healthy
immune systems.
24.After oral antibiotic therapy, a patient is diagnosed with vaginitis.
25.What type of microbe could be causing this opportunistic infection? -
ANSWER Fungus
26.What type of microbe is used to deliver gene therapies to human cells? -
ANSWER Virus
27.What type of diseases are found in higher numbers than expected in local
populations? - ANSWER Epidemic
28.Which describes a mutualistic relationship? - ANSWER Ruminococcus
species using nutrients from a cow's diet to digest plant cellulose in the
rumen.
29.Why are photosynthetic bacteria and algae important to the carbon cycle on
Earth? - ANSWER Photosynthetic microbes metabolize carbon dioxide,
fix carbon, and produce oxygen.
