WGU D311 MICROBIOLOGY EXAM | 200+
QUESTIONS AND CORRECT ANSWERS
WITH RATIONALE | RATED A+ | LATEST
2025
A lab technician performs a Gram stain on a vaginal swab. They see the
expected purple, rod-shaped bacteria. What are the results of this Gram
stain and the shape of the bacteria?
a) Gram-negative coccus
b) Gram-negative bacillus
c) Gram-positive coccus
d) Gram-positive bacillus
- Correct Answer - D
Which of the following is an example of vehicle transmission of a
pathogen?
a) Inhalation of Hantavirus from dust
b) Tetanus from stepping on a rusty nail
c) Flu from a sneeze on an elevator
d) Dysentery from a fly landing on your food
- Correct Answer - A
This is correct. Inhaling microbes that are found on dust is vehicle
transmission. The dust would be the vehicle
,Which of the following is part of the chemical defenses of our innate
immunity?
a) Mucus
b) Microbiome
c) Urination
d) Interferon
- Correct Answer - D
This is an antiviral protein produced by virally infected cells to protect
neighboring ones
What physical control method would you use to sterilize plastic petri
dishes used to grow bacteria in a lab?
a) Gamma rays
b) UV radiation
c) Pasteurization
d) Autoclave
- Correct Answer - A
Gamma rays emit ionizing radiation making it capable of penetrating
paper and plastic; an effective way of sterilizing plastic petri dishes
This type of nonionizing radiation is a good choice for disinfecting
surfaces. It does not have the ability to penetrate
- Correct Answer - UV radiation
,Which of the following vaccines would be the riskiest for a patient that
has received a transplant?
a) Diphtheria
b) Measles
c) Meningitis caused by Neisseria meningitides
d) Anthrax
- Correct Answer - B
This is correct because it is the only option that involves a live
attenuated vaccine
A patient who is immunosuppressed develops skin pustules and itching.
What is a plausible cause of these symptoms?
a) An opportunistic endoparasitic infection
b) An opportunistic bacterial infection
c) An avirulent protozoal infection
d) A highly virulent allergic skin disease
- Correct Answer - B
This is the most correct because the patient's signs are consistent with a
bacterial skin infection. Opportunistic pathogens can only cause disease
in situations where a patient's immune defenses are down which is the
case for this question.
, A culture of fluid collected from a healthy person via a bronchoalveolar
lavage yielded growth of Staphylococcus aureus; however, a culture of a
similarly collected sample from a person sneezing and coughing also
yielded growth of Staphylococcus aureus. How can the same bacteria
cause infection and symptoms in one person but not in another person?
a) Commensal bacteria became opportunistic.
b) Nonpathogenic bacteria became avirulent.
c) Both people must be immunocompromised.
d) One of the samples yielded a false negative result.
- Correct Answer - A
Commensal bacteria can become pathogenic when their growth rate
outnumbers the amount of other bacteria
Why can both cats and people be infected with herpes virus but not
infect each other?
a) Infectivity must be low for these viruses.
b) Innate immunity differs between species.
c) These viruses are species-specific.
d) Virus particles are short-lived.
- Correct Answer - C
Feline herpes virus is specific to cats. Most mammals have their own
type of herpes virus that cannot be transmitted to other species
Fimbria is a virulence factor of Escherichia coli necessary for an infection
to develop. Which treatment may be helpful to prevent urinary tract
QUESTIONS AND CORRECT ANSWERS
WITH RATIONALE | RATED A+ | LATEST
2025
A lab technician performs a Gram stain on a vaginal swab. They see the
expected purple, rod-shaped bacteria. What are the results of this Gram
stain and the shape of the bacteria?
a) Gram-negative coccus
b) Gram-negative bacillus
c) Gram-positive coccus
d) Gram-positive bacillus
- Correct Answer - D
Which of the following is an example of vehicle transmission of a
pathogen?
a) Inhalation of Hantavirus from dust
b) Tetanus from stepping on a rusty nail
c) Flu from a sneeze on an elevator
d) Dysentery from a fly landing on your food
- Correct Answer - A
This is correct. Inhaling microbes that are found on dust is vehicle
transmission. The dust would be the vehicle
,Which of the following is part of the chemical defenses of our innate
immunity?
a) Mucus
b) Microbiome
c) Urination
d) Interferon
- Correct Answer - D
This is an antiviral protein produced by virally infected cells to protect
neighboring ones
What physical control method would you use to sterilize plastic petri
dishes used to grow bacteria in a lab?
a) Gamma rays
b) UV radiation
c) Pasteurization
d) Autoclave
- Correct Answer - A
Gamma rays emit ionizing radiation making it capable of penetrating
paper and plastic; an effective way of sterilizing plastic petri dishes
This type of nonionizing radiation is a good choice for disinfecting
surfaces. It does not have the ability to penetrate
- Correct Answer - UV radiation
,Which of the following vaccines would be the riskiest for a patient that
has received a transplant?
a) Diphtheria
b) Measles
c) Meningitis caused by Neisseria meningitides
d) Anthrax
- Correct Answer - B
This is correct because it is the only option that involves a live
attenuated vaccine
A patient who is immunosuppressed develops skin pustules and itching.
What is a plausible cause of these symptoms?
a) An opportunistic endoparasitic infection
b) An opportunistic bacterial infection
c) An avirulent protozoal infection
d) A highly virulent allergic skin disease
- Correct Answer - B
This is the most correct because the patient's signs are consistent with a
bacterial skin infection. Opportunistic pathogens can only cause disease
in situations where a patient's immune defenses are down which is the
case for this question.
, A culture of fluid collected from a healthy person via a bronchoalveolar
lavage yielded growth of Staphylococcus aureus; however, a culture of a
similarly collected sample from a person sneezing and coughing also
yielded growth of Staphylococcus aureus. How can the same bacteria
cause infection and symptoms in one person but not in another person?
a) Commensal bacteria became opportunistic.
b) Nonpathogenic bacteria became avirulent.
c) Both people must be immunocompromised.
d) One of the samples yielded a false negative result.
- Correct Answer - A
Commensal bacteria can become pathogenic when their growth rate
outnumbers the amount of other bacteria
Why can both cats and people be infected with herpes virus but not
infect each other?
a) Infectivity must be low for these viruses.
b) Innate immunity differs between species.
c) These viruses are species-specific.
d) Virus particles are short-lived.
- Correct Answer - C
Feline herpes virus is specific to cats. Most mammals have their own
type of herpes virus that cannot be transmitted to other species
Fimbria is a virulence factor of Escherichia coli necessary for an infection
to develop. Which treatment may be helpful to prevent urinary tract
