Branches of microbiology MCQs With Answer

Branches of microbiology MCQs With Answer are essential study tools for B. Pharm students preparing for exams and practical applications in pharmacy practice. This concise introduction explores major branches—bacteriology, virology, mycology, parasitology, immunology, clinical and pharmaceutical microbiology—highlighting their relevance to drug development, sterile formulation, infection control, antimicrobial stewardship, and quality assurance. Targeted MCQs reinforce core concepts such as microbial identification, pathogenesis, laboratory techniques, sterilization, antibiotic mechanisms, and biosafety. Optimized for pharmacy learners, these questions improve retention and clinical reasoning while aligning with curriculum needs. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which branch of microbiology primarily studies bacteria, their structure, physiology, and taxonomy?

• Bacteriology
• Virology
• Mycology
• Parasitology

Correct Answer: Bacteriology

Q2. Which branch focuses on viruses, viral replication, and vaccine development?

• Environmental Microbiology
• Virology
• Immunology
• Industrial Microbiology

Correct Answer: Virology

Q3. The study of fungi, including yeasts and molds relevant to drug contamination and mycoses, is called:

• Parasitology
• Mycology
• Bacteriology
• Food Microbiology

Correct Answer: Mycology

Q4. Which branch examines host immune responses, antibody production, and vaccine immunogenicity?

• Immunology
• Clinical Microbiology
• Microbial Genetics
• Virology

Correct Answer: Immunology

Q5. Pharmaceutical microbiology primarily deals with:

• Environmental sampling for air quality only
• Microbial contamination control of drugs and sterility testing
• Plant-microbe interactions for agriculture
• Marine microbial ecology

Correct Answer: Microbial contamination control of drugs and sterility testing

Q6. Which branch studies parasites and their life cycles relevant to antiparasitic drug development?

• Mycology
• Parasitology
• Virology
• Bacteriology

Correct Answer: Parasitology

Q7. The branch that addresses microbes in industrial processes like fermentation for antibiotics is called:

• Industrial Microbiology
• Clinical Microbiology
• Environmental Microbiology
• Medical Entomology

Correct Answer: Industrial Microbiology

Q8. Which technique is commonly used in microbiology labs to quantify viable bacteria in a pharmaceutical sample?

• Serial dilution and plate count
• Gram staining only
• ELISA for proteins
• Thin layer chromatography

Correct Answer: Serial dilution and plate count

Q9. Which staining method differentiates Gram-positive from Gram-negative bacteria?

• Ziehl-Neelsen stain
• Gram stain
• India ink preparation
• Giemsa stain

Correct Answer: Gram stain

Q10. Endotoxins are structural components of which type of bacteria?

• Gram-positive bacteria
• Gram-negative bacteria
• Acid-fast bacteria
• Mycoplasma

Correct Answer: Gram-negative bacteria

Q11. The minimal inhibitory concentration (MIC) is defined as:

• The highest concentration of antibiotic that kills all bacteria
• The lowest concentration of antibiotic that inhibits visible growth
• The concentration that produces a zone of inhibition in mm
• The time required to reduce bacterial count by 90%

Correct Answer: The lowest concentration of antibiotic that inhibits visible growth

Q12. Which test is used to determine antibiotic susceptibility by disk diffusion?

• ELISA
• Kirby-Bauer test
• Western blot
• PCR

Correct Answer: Kirby-Bauer test

Q13. Aseptic processing and sterility assurance in parenteral production most directly relate to which microbiology branch?

• Food Microbiology
• Pharmaceutical Microbiology
• Soil Microbiology
• Bacteriophage Biology

Correct Answer: Pharmaceutical Microbiology

Q14. Which method is preferred to remove bacteria from heat-sensitive pharmaceutical liquids?

• Autoclaving at 121°C
• Membrane filtration (0.22 µm)
• Ultrasonic irradiation
• Dry heat sterilization at 160°C

Correct Answer: Membrane filtration (0.22 µm)

Q15. Which biosafety level (BSL) is appropriate for handling low-risk, well-characterized agents not known to cause disease in healthy adults?

• BSL-1
• BSL-2
• BSL-3
• BSL-4

Correct Answer: BSL-1

Q16. Which laboratory test detects specific antibodies in patient serum using antigen immobilized on a plate?

• PCR
• ELISA
• Gram stain
• Autoclave validation

Correct Answer: ELISA

Q17. The zone of inhibition in disk diffusion reflects which property of the antimicrobial agent?

• Antibiotic concentration only
• In vitro antimicrobial activity and diffusion characteristics
• Host immune response
• Autoclave efficiency

Correct Answer: In vitro antimicrobial activity and diffusion characteristics

Q18. Which molecular technique amplifies a specific DNA region and is widely used for pathogen identification?

• SDS-PAGE
• PCR (Polymerase Chain Reaction)
• Microscopy with Gram stain
• ELISA

Correct Answer: PCR (Polymerase Chain Reaction)

Q19. Which growth phase is characterized by rapid cell division and maximum metabolic activity?

• Lag phase
• Log (exponential) phase
• Stationary phase
• Death phase

Correct Answer: Log (exponential) phase

Q20. Which microbial structure is primarily responsible for antibiotic resistance transfer via conjugation?

• R plasmid (F plasmid)
• Peptidoglycan layer
• Capsule
• Endospore

Correct Answer: R plasmid (F plasmid)

Q21. Which of the following is a common method for sterilizing surgical instruments and heat-stable glassware?

• Membrane filtration
• Autoclaving (steam under pressure)
• Ion-exchange chromatography
• Refrigeration

Correct Answer: Autoclaving (steam under pressure)

Q22. Which pathogen detection method directly measures bacterial endotoxin in pharmaceutical products?

• Gram staining
• LAL (Limulus Amebocyte Lysate) test
• Kirby-Bauer disk diffusion
• Western blot

Correct Answer: LAL (Limulus Amebocyte Lysate) test

Q23. Biofilms in pharmaceutical production can cause persistent contamination because microorganisms in biofilms are:

• More susceptible to antibiotics
• Less metabolically active and more resistant to disinfectants
• Always non-pathogenic
• Easily removed by mild detergents

Correct Answer: Less metabolically active and more resistant to disinfectants

Q24. Which branch studies microbial roles in soil, water, and biogeochemical cycles relevant to environmental drug impact?

• Environmental Microbiology
• Clinical Microbiology
• Mycology
• Food Microbiology

Correct Answer: Environmental Microbiology

Q25. Which specific test differentiates Mycobacterium tuberculosis from other bacteria due to waxy cell wall components?

• Gram stain
• Acid-fast (Ziehl-Neelsen) stain
• India ink
• Endospore stain

Correct Answer: Acid-fast (Ziehl-Neelsen) stain

Q26. In sterile product testing, the term “bioburden” refers to:

• The number of viable microorganisms on or in a product before sterilization
• The endotoxin level after sterilization
• The total number of dead cells present
• The concentration of preservatives

Correct Answer: The number of viable microorganisms on or in a product before sterilization

Q27. Which mechanism of antibiotic resistance involves enzymatic breakdown of the drug, e.g., beta-lactamases?

• Target modification
• Enzymatic inactivation
• Efflux pump activation
• Decreased permeability

Correct Answer: Enzymatic inactivation

Q28. Which culture medium is selective for Gram-negative enteric bacteria and differentiates lactose fermenters?

• Blood agar
• MacConkey agar
• Sabouraud dextrose agar
• Thayer-Martin agar

Correct Answer: MacConkey agar

Q29. Phage therapy uses bacteriophages to treat bacterial infections. This approach falls under which applied branch?

• Environmental Microbiology
• Bacteriophage Therapy / Clinical Microbiology
• Mycology
• Immunology only

Correct Answer: Bacteriophage Therapy / Clinical Microbiology

Q30. Which method is best for detecting viral RNA in patient samples with high sensitivity?

• Conventional culture on blood agar
• RT-PCR (Reverse Transcription PCR)
• Gram stain
• Protein electrophoresis

Correct Answer: RT-PCR (Reverse Transcription PCR)

Q31. Exotoxins differ from endotoxins because exotoxins are:

• Heat-stable lipopolysaccharides
• Proteinaceous and secreted by Gram-positive and Gram-negative bacteria
• Only found in Gram-negative cell walls
• Non-immunogenic

Correct Answer: Proteinaceous and secreted by Gram-positive and Gram-negative bacteria

Q32. What is the principle of sterilizing filtration used for heat-labile solutions?

• Use of 0.22 µm membrane to physically remove microorganisms
• Use of alcohol to kill spores
• Heating at 60°C for 10 minutes
• Adding antibiotics to the solution

Correct Answer: Use of 0.22 µm membrane to physically remove microorganisms

Q33. Which technique helps identify bacteria based on fatty acid profiles and phenotypic traits for difficult isolates?

• FAME analysis (Fatty Acid Methyl Ester)
• ELISA
• LAL test
• Gram stain only

Correct Answer: FAME analysis (Fatty Acid Methyl Ester)

Q34. Which genetic element is most commonly associated with horizontal gene transfer via bacteriophage?

• Plasmid conjugation only
• Transduction involving bacteriophages
• Transformation by naked DNA only
• Endospore formation

Correct Answer: Transduction involving bacteriophages

Q35. Which microbial detection method is culture-independent and useful for analyzing complex microbiomes?

• Culture on selective media
• Metagenomic sequencing
• Gram stain
• Routine sterility test

Correct Answer: Metagenomic sequencing

Q36. In vaccine production, which branch ensures antigen purity, potency, and sterility?

• Industrial Microbiology
• Pharmaceutical Microbiology
• Environmental Microbiology
• Food Microbiology

Correct Answer: Pharmaceutical Microbiology

Q37. Which method assesses the presence of mycoplasma contamination in cell culture used in drug testing?

• PCR-based mycoplasma detection
• Gram staining
• Autoclave validation
• Endotoxin testing only

Correct Answer: PCR-based mycoplasma detection

Q38. Which organism forms highly resistant endospores that challenge sterilization in pharmaceutical settings?

• Escherichia coli
• Bacillus and Clostridium species
• Staphylococcus aureus
• Candida albicans

Correct Answer: Bacillus and Clostridium species

Q39. Which analytical method is commonly used to monitor sterilizer performance and operator technique in aseptic areas?

• Environmental monitoring (air, surfaces, personnel)
• PCR of staff DNA
• SDS-PAGE of products
• Food spoilage tests

Correct Answer: Environmental monitoring (air, surfaces, personnel)

Q40. Transposons contribute to antimicrobial resistance by which mechanism?

• Spontaneous mutation of ribosomes
• Mobilization and insertion of resistance genes into chromosomes or plasmids
• Forming biofilms
• Producing exotoxins

Correct Answer: Mobilization and insertion of resistance genes into chromosomes or plasmids

Q41. Which serological test detects antigens or antibodies using labeled antibodies for rapid diagnosis?

• ELISA lateral flow assays (rapid tests)
• Culture on selective agar
• Endotoxin LAL test
• Autoclave spore test

Correct Answer: ELISA lateral flow assays (rapid tests)

Q42. Which branch involves study of microbes that degrade pollutants and can be used in bioremediation?

• Industrial Microbiology
• Environmental Microbiology
• Clinical Microbiology
• Mycology only

Correct Answer: Environmental Microbiology

Q43. Which technique separates proteins by size and is useful in identifying microbial proteins or toxins?

• SDS-PAGE
• Gram staining
• PCR
• Autoclaving

Correct Answer: SDS-PAGE

Q44. Which organism is a common cause of fungal contamination in pharmaceutical products and is detected on Sabouraud dextrose agar?

• Streptococcus pneumoniae
• Pseudomonas aeruginosa
• Aspergillus species
• Mycobacterium tuberculosis

Correct Answer: Aspergillus species

Q45. MIC and MBC (minimum bactericidal concentration) help determine whether an antibiotic is:

• Bacteriostatic or bactericidal
• A vaccine adjuvant
• An antifungal only
• A disinfectant efficacy

Correct Answer: Bacteriostatic or bactericidal

Q46. Horizontal gene transfer by naked DNA uptake from the environment is called:

• Conjugation
• Transformation
• Transduction
• Binary fission

Correct Answer: Transformation

Q47. Which disinfectant is widely used for surface disinfection and inactivates a broad spectrum of microbes including enveloped viruses?

• 70% isopropyl alcohol
• Pure water
• Olive oil
• Glycerin

Correct Answer: 70% isopropyl alcohol

Q48. Which laboratory quality control practice verifies that autoclave cycles achieve required time, temperature, and pressure?

• Use of biological indicators (spore strips)
• Gram staining
• ELISA
• Visual inspection only

Correct Answer: Use of biological indicators (spore strips)

Q49. Which microbiology branch focuses on the study of microbes used in food production, spoilage prevention, and probiotic development?

• Food Microbiology
• Clinical Microbiology
• Mycology only
• Virology only

Correct Answer: Food Microbiology

Q50. Which molecular typing method distinguishes bacterial strains based on DNA fragment patterns after restriction enzyme digestion and gel electrophoresis?

• Pulsed-field gel electrophoresis (PFGE)
• Gram staining
• ELISA
• LAL test

Correct Answer: Pulsed-field gel electrophoresis (PFGE)

G S Sachin

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.

Mail- Sachin@pharmacyfreak.com