IRENE GOLD
MICROBIOLOGY BOARDS
EXAM NEWEST ACTUAL
EXAM COMPLETE 200+
QUESTIONS AND
CORRECT DETAILED
ANSWERS (VERIFIED
ANSWERS)
|ALREADYGRADED A+
1. Which of the following is the most common cause of bacterial
pneumonia in adults?
● A. Streptococcus pneumoniae
● B. Haemophilus influenzae
● C. Mycoplasma pneumoniae
● D. Klebsiella pneumoniae
Answer: A. Streptococcus pneumoniae
Explanation: Streptococcus pneumoniae is the most common cause of community-acquired
bacterial pneumonia in adults. It is a Gram-positive, encapsulated bacterium that typically
presents with symptoms like high fever, chills, productive cough, and pleuritic chest pain.
2. Which virus is associated with causing mononucleosis?
, ● A. Epstein-Barr Virus (EBV)
● B. Cytomegalovirus (CMV)
● C. Varicella-Zoster Virus (VZV)
● D. Human Immunodeficiency Virus (HIV)
Answer: A. Epstein-Barr Virus (EBV)
Explanation: The Epstein-Barr virus (EBV) is most commonly associated with infectious
mononucleosis, which presents with fever, pharyngitis, and lymphadenopathy. It is part of the
herpesvirus family and is transmitted through saliva.
3. Which of the following bacterial organisms is most likely to cause food
poisoning with rapid onset (within 1-6 hours)?
● A. Clostridium perfringens
● B. Salmonella spp.
● C. Staphylococcus aureus
● D. Escherichia coli
Answer: C. Staphylococcus aureus
Explanation: Staphylococcus aureus produces a heat-stable enterotoxin that can cause food
poisoning with rapid onset of symptoms, typically within 1 to 6 hours. Symptoms include
nausea, vomiting, and abdominal cramps.
4. What is the primary mode of transmission for Hepatitis B virus?
● A. Fecal-oral
● B. Respiratory droplets
● C. Blood and body fluids
● D. Contaminated food and water
Answer: C. Blood and body fluids
Explanation: Hepatitis B virus (HBV) is primarily transmitted through exposure to infected
blood, sexual contact, and perinatal transmission from mother to child. It can lead to chronic
liver disease, including cirrhosis and hepatocellular carcinoma.
5. Which of the following bacteria is classified as an obligate intracellular
pathogen?
● A. Neisseria gonorrhoeae
● B. Listeria monocytogenes
● C. Rickettsia rickettsii
● D. Clostridium botulinum
,Answer: C. Rickettsia rickettsii
Explanation: Rickettsia rickettsii is an obligate intracellular bacterium that causes Rocky
Mountain spotted fever. It requires host cells to survive and multiply, and it is transmitted by
ticks.
6. Which of the following is the causative agent of Lyme disease?
● A. Treponema pallidum
● B. Borrelia burgdorferi
● C. Rickettsia prowazekii
● D. Francisella tularensis
Answer: B. Borrelia burgdorferi
Explanation: Borrelia burgdorferi is a spirochete bacterium that causes Lyme disease, which
is transmitted by the bite of infected Ixodes ticks. Early symptoms include erythema migrans
(bull's-eye rash), fever, and fatigue.
7. Which of the following fungi is most likely to cause an infection in
immunocompromised patients, especially those with HIV/AIDS?
● A. Candida albicans
● B. Histoplasma capsulatum
● C. Cryptococcus neoformans
● D. Aspergillus fumigatus
Answer: C. Cryptococcus neoformans
Explanation: Cryptococcus neoformans is an encapsulated yeast that commonly causes
meningitis in immunocompromised individuals, particularly those with HIV/AIDS. It is acquired
by inhaling the fungus from the environment, often from bird droppings.
8. Which of the following bacterial toxins is associated with the inhibition of
protein synthesis, leading to cell death?
● A. Botulinum toxin
● B. Cholera toxin
● C. Diphtheria toxin
● D. Tetanospasmin
Answer: C. Diphtheria toxin
Explanation: Diphtheria toxin, produced by Corynebacterium diphtheriae, inhibits protein
synthesis by ADP-ribosylating elongation factor-2 (EF-2), leading to cell death. This toxin
causes the severe symptoms seen in diphtheria, such as pseudomembrane formation in the
throat.
, 9. Which of the following organisms is a Gram-negative diplococcus and is
a common cause of sexually transmitted infections?
● A. Escherichia coli
● B. Neisseria gonorrhoeae
● C. Treponema pallidum
● D. Chlamydia trachomatis
Answer: B. Neisseria gonorrhoeae
Explanation: Neisseria gonorrhoeae is a Gram-negative diplococcus that causes gonorrhea, a
sexually transmitted infection characterized by purulent discharge and, in some cases, pelvic
inflammatory disease.
10. Which of the following bacteria is responsible for causing whooping
cough?
● A. Bordetella pertussis
● B. Haemophilus influenzae
● C. Legionella pneumophila
● D. Streptococcus pyogenes
Answer: A. Bordetella pertussis
Explanation: Bordetella pertussis is the causative agent of whooping cough (pertussis), a
highly contagious respiratory disease that causes severe coughing fits followed by a "whooping"
sound during inhalation.
11. What is the causative agent of syphilis?
● A. Neisseria gonorrhoeae
● B. Chlamydia trachomatis
● C. Treponema pallidum
● D. Haemophilus ducreyi
Answer: C. Treponema pallidum
Explanation: Treponema pallidum is a spirochete bacterium that causes syphilis, a sexually
transmitted infection. It progresses through stages, starting with a painless sore (chancre) and,
if untreated, can lead to systemic and neurological damage.
12. Which bacterium is the most common cause of urinary tract infections?
● A. Staphylococcus saprophyticus
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