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: Capsid in a virus serves to
A) Aid in replication
B) Form the viral envelope
C) Enclose the genetic material
D) Provide energy
✅ Correct Answer: C
Explanation: The capsid is a protein shell that protects the viral nucleic acid and assists in host infection.
Q: The process of killing all microbial life, including spores, is called
A) Disinfection
B) Antisepsis
C) Sterilization
D) Pasteurization
✅ Correct Answer: C
Explanation: Sterilization ensures complete destruction of all microorganisms, including heat-resistant spores.
Q: The major reservoir of Salmonella typhi is
A) Rodents
B) Soil
C) Water
D) Human gastrointestinal tract
✅ Correct Answer: D
Explanation: Humans are the only known reservoir for Salmonella typhi, the bacterium responsible for typhoid fever.
Q: Bacterial resistance to antibiotics is often carried on
A) Nucleus
B) Ribosomes
C) Plasmids
D) Cell membrane
✅ Correct Answer: C
Explanation: Plasmids often contain genes that confer resistance to antibiotics, facilitating rapid spread.
Q: Anthrax is caused by
A) Listeria monocytogenes
B) Escherichia coli
C) Bacillus anthracis
D) Clostridium botulinum
✅ Correct Answer: C
Explanation: Bacillus anthracis produces spores and a toxin that causes anthrax in humans and animals.
Q: Molecular identification of bacteria commonly uses
A) Ribosomal RNA sequences
B) Antibiotic testing
C) Flagellar staining
D) Capsule staining
✅ Correct Answer: A
Explanation: 16S rRNA gene sequencing is widely used for bacterial identification due to its highly conserved nature.
Q: The skin microbiota includes
A) A diverse group of microbes
B) Only viruses
C) Only harmful bacteria
D) Only Gram-negative bacteria
✅ Correct Answer: A
Explanation: Normal skin flora includes bacteria, fungi, and viruses that coexist and often protect against pathogens.
Q: Acquired immunity results from
A) Physical barriers
B) Direct exposure to antigens
C) Passive antibody transfer
D) Genetic inheritance
✅ Correct Answer: B
Explanation: Acquired immunity develops after exposure to antigens through infection or vaccination.
Q: The time between exposure to a pathogen and appearance of symptoms is called
A) Incubation period
B) Convalescence
C) Infectious period
D) Prodromal stage
✅ Correct Answer: A
Explanation: The incubation period is the interval between infection and the onset of clinical symptoms.
Q: Fungi differ from bacteria by having
A) Eukaryotic cell structure
B) No nucleus
C) Circular DNA
D) Peptidoglycan in the cell wall
✅ Correct Answer: A
Explanation: Fungi are eukaryotic and possess a true nucleus and organelles, unlike bacteria.