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: Sterilization ensures
A) Reduction in microbial count
B) Destruction of all microbial life
C) Removal of dust
D) Killing of pathogens only
✅ Correct Answer: B
Explanation: Sterilization completely eliminates all forms of microbial life, including spores.
Q: Penicillin was discovered by
A) Alexander Fleming
B) Joseph Lister
C) Robert Koch
D) Louis Pasteur
✅ Correct Answer: A
Explanation: Alexander Fleming discovered penicillin, the first widely used antibiotic, in 1928.
Q: A capsule in bacteria functions to
A) Increase nutrient uptake
B) Synthesize proteins
C) Aid motility
D) Evade immune response
✅ Correct Answer: D
Explanation: The bacterial capsule helps prevent phagocytosis by host immune cells, enhancing pathogenicity.
Q: Plasmids in bacteria are
A) Extrachromosomal DNA
B) RNA fragments
C) Structural components
D) Sites of protein synthesis
✅ Correct Answer: A
Explanation: Plasmids are circular DNA molecules that often carry antibiotic resistance or virulence genes.
Q: Obligate aerobes require
A) High temperatures
B) Low pH
C) Oxygen for survival
D) Carbon dioxide
✅ Correct Answer: C
Explanation: Obligate aerobes depend on oxygen for energy production via aerobic respiration.
Q: Binary fission in bacteria leads to
A) Genetic recombination
B) Sexual reproduction
C) Spore formation
D) Asexual reproduction
✅ Correct Answer: D
Explanation: Binary fission is an asexual process where a single bacterium divides into two identical daughter cells.
Q: The gram-negative cell wall contains
A) Teichoic acids
B) Lipopolysaccharide layer
C) Mycolic acid
D) Thick peptidoglycan
✅ Correct Answer: B
Explanation: Gram-negative bacteria have an outer membrane rich in lipopolysaccharides which contributes to pathogenicity.
Q: An example of a dimorphic fungus is
A) Mucor
B) Aspergillus niger
C) Cryptococcus neoformans
D) Candida albicans
✅ Correct Answer: D
Explanation: Candida albicans can exist in both yeast and filamentous forms, making it dimorphic.
Q: The function of pili in bacteria is to
A) Aid in attachment
B) Facilitate movement
C) Break down toxins
D) Protect against antibiotics
✅ Correct Answer: A
Explanation: Pili are hair-like structures that help bacteria attach to host tissues or surfaces.
Q: The term “acid-fast” refers to organisms that
A) Lose the primary stain easily
B) Are sensitive to acid
C) Retain stain after acid-alcohol wash
D) Live in acidic environments
✅ Correct Answer: C
Explanation: Acid-fast organisms resist decolorization due to the high lipid content in their cell walls.