Microbiology MCQs with answer are essential study tools for B. Pharm students preparing for exams and clinical practice. Mastery of bacteriology, virology, mycology, parasitology, immunology, and antimicrobial pharmacology helps students understand pathogen identification, sterilization, laboratory techniques, and antibiotic resistance. Practicing targeted multiple-choice questions improves recall, sharpens diagnostic reasoning, and reinforces laboratory safety and quality control concepts. High-quality microbiology MCQs aligned with the B. Pharm curriculum also boost confidence for practical exams and competitive tests. Focused practice on culture media, staining methods, biochemical tests, and mechanisms of action of antimicrobials bridges theory with pharmacy applications. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which bacterial structure is primarily responsible for motility?
- Capsule
- Flagellum
- Pilus
- Cell wall
Correct Answer: Flagellum
Q2. Gram-positive bacteria are characterized by which feature?
- Thin peptidoglycan layer and outer membrane
- Thick peptidoglycan layer and teichoic acids
- Lack of peptidoglycan
- Presence of lipopolysaccharide
Correct Answer: Thick peptidoglycan layer and teichoic acids
Q3. Which staining method is best for detecting Mycobacterium tuberculosis?
- Gram stain
- India ink stain
- Ziehl-Neelsen (acid-fast) stain
- Capsule stain
Correct Answer: Ziehl-Neelsen (acid-fast) stain
Q4. Autoclaving is effective for sterilization because it uses which combination?
- Dry heat and long exposure
- High pressure and moist heat (steam)
- Chemical disinfectants at room temperature
- UV radiation and airflow
Correct Answer: High pressure and moist heat (steam)
Q5. Which medium is selective for Gram-negative enteric bacteria and differentiates lactose fermenters?
- Blood agar
- MacConkey agar
- Mannitol salt agar
- Sabouraud dextrose agar
Correct Answer: MacConkey agar
Q6. Beta-lactam antibiotics act by inhibiting which bacterial process?
- Protein synthesis at 30S ribosome
- Folate synthesis
- Peptidoglycan cross-linking (cell wall synthesis)
- DNA gyrase activity
Correct Answer: Peptidoglycan cross-linking (cell wall synthesis)
Q7. Which enzyme confers resistance to penicillins by hydrolyzing the beta-lactam ring?
- Aminoglycoside-modifying enzyme
- Beta-lactamase
- Ribosomal methylase
- DNA polymerase
Correct Answer: Beta-lactamase
Q8. The Kirby-Bauer test is used to assess what property of bacteria?
- Growth rate in liquid medium
- Antibiotic susceptibility (zone of inhibition)
- Capsule presence
- Spore formation
Correct Answer: Antibiotic susceptibility (zone of inhibition)
Q9. Which virus family has a double-stranded DNA genome and enveloped particles?
- Picornaviridae
- Herpesviridae
- Orthomyxoviridae
- Retroviridae
Correct Answer: Herpesviridae
Q10. Which biochemical test detects the presence of catalase enzyme?
- Oxidase test
- Catalase test (bubbling with hydrogen peroxide)
- Coagulase test
- Urease test
Correct Answer: Catalase test (bubbling with hydrogen peroxide)
Q11. Endotoxin is associated with which bacterial component?
- Peptidoglycan
- Lipopolysaccharide (LPS) of Gram-negative outer membrane
- Exotoxin secreted by Gram-positive bacteria
- Capsular polysaccharide
Correct Answer: Lipopolysaccharide (LPS) of Gram-negative outer membrane
Q12. Which method is commonly used to quantify bacteria in a liquid culture by serial dilution and plating?
- Direct microscopy counting
- Colony-forming unit (CFU) counting
- Flow cytometry
- ELISA
Correct Answer: Colony-forming unit (CFU) counting
Q13. Which vaccine type contains inactivated whole organisms and often requires adjuvants?
- Live attenuated vaccine
- Subunit vaccine
- Inactivated (killed) vaccine
- Conjugate vaccine
Correct Answer: Inactivated (killed) vaccine
Q14. PCR (polymerase chain reaction) is primarily used to:
- Separate proteins by size
- Amplify specific DNA sequences
- Measure antimicrobial sensitivity
- Stain bacteria for microscopy
Correct Answer: Amplify specific DNA sequences
Q15. Which organism is known for forming endospores resistant to heat and disinfectants?
- Escherichia coli
- Staphylococcus aureus
- Bacillus anthracis
- Mycoplasma pneumoniae
Correct Answer: Bacillus anthracis
Q16. Which antibiotic inhibits protein synthesis by binding to the 30S ribosomal subunit?
- Chloramphenicol
- Gentamicin
- Vancomycin
- Ciprofloxacin
Correct Answer: Gentamicin
Q17. A positive coagulase test helps identify which species?
- Staphylococcus aureus
- Streptococcus pyogenes
- Escherichia coli
- Pseudomonas aeruginosa
Correct Answer: Staphylococcus aureus
Q18. Which assay is commonly used to detect antigens or antibodies using enzyme-linked reactions?
- Western blot
- Flow cytometry
- ELISA (enzyme-linked immunosorbent assay)
- Gram staining
Correct Answer: ELISA (enzyme-linked immunosorbent assay)
Q19. Which organism is a common cause of hospital-acquired infections and is often multidrug-resistant?
- Staphylococcus epidermidis
- Pseudomonas aeruginosa
- Lactobacillus acidophilus
- Bacteroides fragilis
Correct Answer: Pseudomonas aeruginosa
Q20. Which antifungal targets ergosterol in fungal cell membranes?
- Penicillin
- Amphotericin B
- Rifampicin
- Metronidazole
Correct Answer: Amphotericin B
Q21. The growth phase where bacteria adapt to a new environment with little or no cell division is called:
- Log (exponential) phase
- Stationary phase
- Lag phase
- Death phase
Correct Answer: Lag phase
Q22. Which test differentiates Streptococcus pneumoniae from viridans streptococci?
- Bacitracin sensitivity
- Optochin sensitivity and bile solubility
- Catalase test
Correct Answer: Optochin sensitivity and bile solubility
Q23. Which organism lacks a cell wall and is intrinsically resistant to beta-lactam antibiotics?
- Mycoplasma pneumoniae
- Staphylococcus aureus
- Escherichia coli
- Clostridium difficile
Correct Answer: Mycoplasma pneumoniae
Q24. In viral replication, reverse transcriptase is characteristic of which group?
- Positive-sense RNA viruses (non-retro)
- Retroviruses (e.g., HIV)
- DNA viruses
- Negative-sense RNA viruses
Correct Answer: Retroviruses (e.g., HIV)
Q25. Which disinfectant is best known for sporicidal activity when used properly?
- Ethanol 70%
- Chlorhexidine
- Glutaraldehyde
- Soap and water
Correct Answer: Glutaraldehyde
Q26. Which test indicates bacterial fermentation of glucose with acid and gas production?
- Oxidase test
- TSI (triple sugar iron) agar test
- Catalase test
- Coagulase test
Correct Answer: TSI (triple sugar iron) agar test
Q27. Conjugation in bacteria primarily transfers which genetic element?
- Chromosomal genes only
- Plasmids via a sex pilus
- Viral DNA via transduction
- Free DNA uptake via transformation
Correct Answer: Plasmids via a sex pilus
Q28. Which protozoan parasite causes malabsorption and chronic diarrhea and is transmitted by contaminated water?
- Plasmodium falciparum
- Giardia lamblia
- Trypanosoma cruzi
- Entamoeba histolytica
Correct Answer: Giardia lamblia
Q29. Which antibiotic class interferes with DNA gyrase in bacteria?
- Macrolides
- Fluoroquinolones
- Aminoglycosides
- Glycopeptides
Correct Answer: Fluoroquinolones
Q30. Which organism is the primary causative agent of pseudomembranous colitis after antibiotic therapy?
- Clostridium tetani
- Clostridium difficile
- Clostridium perfringens
- Clostridium botulinum
Correct Answer: Clostridium difficile
Q31. Which serological test detects recent infection by measuring IgM antibodies?
- Western blot
- IgM-specific ELISA
- Culture on selective media
- Gram staining
Correct Answer: IgM-specific ELISA
Q32. Which of the following organisms is acid-fast positive?
- Escherichia coli
- Mycobacterium leprae
- Staphylococcus aureus
- Pseudomonas aeruginosa
Correct Answer: Mycobacterium leprae
Q33. A bacteriophage-mediated transfer of bacterial DNA is called:
- Transformation
- Conjugation
- Transduction
- Transposition
Correct Answer: Transduction
Q34. Which nutrient agar is primarily used for fungal isolation in the lab?
- Blood agar
- MacConkey agar
- Sabouraud dextrose agar
- Chocolate agar
Correct Answer: Sabouraud dextrose agar
Q35. Methicillin-resistant Staphylococcus aureus (MRSA) resistance is mainly due to:
- Beta-lactamase overproduction
- Altered penicillin-binding protein (PBP2a) encoded by mecA
- Efflux pumps only
- Lack of peptidoglycan
Correct Answer: Altered penicillin-binding protein (PBP2a) encoded by mecA
Q36. Which test distinguishes between Enterococcus and group D streptococci using bile esculin?
- Bile esculin hydrolysis test
- Coagulase test
- Oxidase test
- Urease test
Correct Answer: Bile esculin hydrolysis test
Q37. Which viral component determines host range and tissue tropism?
- Capsid proteins and viral surface glycoproteins
- Viral RNA polymerase only
- Host ribosomes
- Peptidoglycan layer
Correct Answer: Capsid proteins and viral surface glycoproteins
Q38. Which antimicrobial is commonly used to treat anaerobic infections like Bacteroides fragilis?
- Metronidazole
- Ampicillin
- Tobramycin
- Fluconazole
Correct Answer: Metronidazole
Q39. Which lab safety level is appropriate for handling agents like Mycobacterium tuberculosis?
- BSL-1
- BSL-2
- BSL-3
- BSL-4
Correct Answer: BSL-3
Q40. In ELISA, a color change indicates the presence of which of the following?
- DNA amplification
- Antigen-antibody binding detected by an enzyme-substrate reaction
- Bacterial growth on agar
- Presence of endotoxin only
Correct Answer: Antigen-antibody binding detected by an enzyme-substrate reaction
Q41. Which of the following is a naked (non-enveloped) DNA virus?
- Hepatitis B virus
- Adenovirus
- Influenza virus
- HSV-1
Correct Answer: Adenovirus
Q42. Which fungal infection is commonly associated with systemic candidiasis in immunocompromised patients?
- Aspergillosis
- Candidemia
- Dermatophytosis
- Histoplasmosis
Correct Answer: Candidemia
Q43. Which metabolic pathway is targeted by sulfonamides in bacteria?
- Peptidoglycan synthesis
- Folate synthesis (dihydropteroate synthase)
- Protein synthesis at 50S ribosome
- DNA replication
Correct Answer: Folate synthesis (dihydropteroate synthase)
Q44. Which diagnostic method provides rapid identification of bacteria by mass spectrometry?
- MALDI-TOF MS
- Gram stain
- ELISA
- PCR only
Correct Answer: MALDI-TOF MS
Q45. Which phase of bacterial growth is characterized by balanced growth where cell division equals cell death?
- Lag phase
- Log (exponential) phase
- Stationary phase
- Death phase
Correct Answer: Stationary phase
Q46. Which class of antibiotics is contraindicated in young children due to effects on cartilage development?
- Macrolides
- Fluoroquinolones
- Beta-lactams
- Glycopeptides
Correct Answer: Fluoroquinolones
Q47. Horizontal gene transfer by uptake of naked DNA from the environment is called:
- Transformation
- Transduction
- Conjugation
- Recombination only
Correct Answer: Transformation
Q48. Which lab technique separates DNA fragments by size using an electric field?
- Chromatography
- Gel electrophoresis
- Flow cytometry
- Mass spectrometry
Correct Answer: Gel electrophoresis
Q49. Which organism causes rice-water stools in severe watery diarrhea outbreaks?
- Salmonella typhi
- Vibrio cholerae
- Shigella dysenteriae
- Campylobacter jejuni
Correct Answer: Vibrio cholerae
Q50. Which mechanism do aminoglycosides primarily use to kill bacteria?
- Inhibit cell wall synthesis
- Bind 30S ribosomal subunit causing misreading of mRNA
- Disrupt cell membrane ergosterol
- Inhibit DNA gyrase
Correct Answer: Bind 30S ribosomal subunit causing misreading of mRNA
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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