Microbiology MCQs
Microbiology MCQs challenge students to identify pathogens, understand microbial physiology, and master infection control protocols. These questions span bacteriology, virology, mycology, parasitology, and immunology. Suitable for exams like MDCAT, FCPS, NTS, and USMLE, these quizzes improve both academic knowledge and clinical readiness.
Q: Prions are infectious agents composed only of
A) DNA
B) Protein
C) RNA
D) Lipid
✅ Correct Answer: B
Explanation: Prions lack nucleic acids and are infectious misfolded proteins causing neurodegenerative diseases.
Q: The primary vector for Dengue fever is
A) Tsetse fly
B) Culex mosquito
C) Aedes aegypti
D) Sandfly
✅ Correct Answer: C
Explanation: Aedes aegypti mosquitoes are responsible for spreading Dengue virus in tropical regions.
Q: Bacterial conjugation involves
A) Spore formation
B) Binary fission
C) Transformation
D) Plasmid transfer
✅ Correct Answer: D
Explanation: Conjugation allows bacteria to transfer plasmid DNA through a pilus from one cell to another.
Q: The causative agent of syphilis is
A) Treponema pallidum
B) Neisseria gonorrhoeae
C) Chlamydia trachomatis
D) Haemophilus ducreyi
✅ Correct Answer: A
Explanation: Treponema pallidum is a spirochete bacterium that causes the sexually transmitted disease syphilis.
Q: The Gram stain was developed by
A) Hans Christian Gram
B) Louis Pasteur
C) Robert Koch
D) Paul Ehrlich
✅ Correct Answer: A
Explanation: Hans Christian Gram created the Gram staining technique to differentiate bacteria based on cell wall composition.
Q: Hepatitis B is primarily transmitted via
A) Blood and body fluids
B) Fecal-oral route
C) Airborne droplets
D) Contaminated food
✅ Correct Answer: A
Explanation: Hepatitis B virus spreads through exposure to infected blood, sexual contact, and perinatal transmission.
Q: Flagella arrangement around the bacterial cell body is described as
A) Diplotrichous
B) Helicoidal
C) Biflagellar
D) Monotrichous
✅ Correct Answer: D
Explanation: Monotrichous flagella refer to a single flagellum located at one pole of a bacterial cell.
Q: Tuberculosis affects primarily the
A) Skin
B) Liver
C) Intestine
D) Lungs
✅ Correct Answer: D
Explanation: Mycobacterium tuberculosis most commonly infects the lungs, causing respiratory symptoms.
Q: A facultative anaerobe grows
A) With or without oxygen
B) Only with oxygen
C) Only without oxygen
D) Only in darkness
✅ Correct Answer: A
Explanation: Facultative anaerobes can survive in both aerobic and anaerobic conditions by switching metabolic pathways.
Q: An enzyme used in PCR derived from Thermus aquaticus is
A) Amylase
B) Taq polymerase
C) Reverse transcriptase
D) DNA polymerase
✅ Correct Answer: B
Explanation: Taq polymerase is a heat-stable enzyme used to amplify DNA in the polymerase chain reaction.