Microbiology MCQs

Which of the following is a prokaryotic cell?
- A) Plant cell
- B) Animal cell
- C) Bacterial cell
- D) Fungal cell
- Answer: C) Bacterial cell
Which bacterial structure is responsible for attachment to surfaces?
- A) Capsule
- B) Flagella
- C) Pili
- D) Ribosomes
- Answer: C) Pili
The Gram staining technique differentiates bacteria based on their:
- A) Shape
- B) Size
- C) Cell wall composition
- D) Metabolic activity
- Answer: C) Cell wall composition
Which of the following is an example of a pathogenic fungus?
- A) Saccharomyces cerevisiae
- B) Aspergillus niger
- C) Candida albicans
- D) Penicillium notatum
- Answer: C) Candida albicans
Which of the following is not a characteristic of viruses?
- A) They are obligate intracellular parasites
- B) They contain ribosomes
- C) They have either DNA or RNA
- D) They lack cellular structure
- Answer: B) They contain ribosomes
In the bacterium Escherichia coli, the plasmids are:
- A) Essential for survival
- B) Part of the chromosomal DNA
- C) Circular DNA molecules
- D) Organelles
- Answer: C) Circular DNA molecules
Which of the following is a common method for sterilizing heat-sensitive materials?
- A) Autoclaving
- B) Boiling
- C) Filtration
- D) Incineration
- Answer: C) Filtration
The process of converting nitrogen gas to ammonia is called:
- A) Nitrogen fixation
- B) Nitrification
- C) Denitrification
- D) Ammonification
- Answer: A) Nitrogen fixation
Which antibiotic targets bacterial cell wall synthesis?
- A) Tetracycline
- B) Penicillin
- C) Streptomycin
- D) Erythromycin
- Answer: B) Penicillin
Which type of microorganism is responsible for causing malaria?
- A) Bacterium
- B) Virus
- C) Protozoan
- D) Fungus
- Answer: C) Protozoan
Which of the following is a characteristic of all viruses?
- A) Presence of ribosomes
- B) Cellular structure
- C) Protein coat (capsid)
- D) Ability to reproduce independently
- Answer: C) Protein coat (capsid)
Which medium is used to culture bacteria in the laboratory?
- A) Agar
- B) Gelatin
- C) Nutrient broth
- D) Both A and C
- Answer: D) Both A and C
Which technique is used to separate DNA fragments based on size?
- A) PCR
- B) Gel electrophoresis
- C) Western blotting
- D) ELISA
- Answer: B) Gel electrophoresis
Which type of immunity involves antibodies circulating in blood?
- A) Cell-mediated immunity
- B) Humoral immunity
- C) Innate immunity
- D) Adaptive immunity
- Answer: B) Humoral immunity
The term ‘aseptic technique’ refers to:
- A) Techniques for killing bacteria
- B) Techniques to avoid contamination
- C) Techniques for growing bacteria
- D) Techniques for identifying bacteria
- Answer: B) Techniques to avoid contamination
Which bacterium is known for causing tuberculosis?
- A) Mycobacterium tuberculosis
- B) Escherichia coli
- C) Staphylococcus aureus
- D) Bacillus anthracis
- Answer: A) Mycobacterium tuberculosis
Which of the following is a method of genetic recombination in bacteria?
- A) Transformation
- B) Mutation
- C) Binary fission
- D) Conjugation
- Answer: A) Transformation
Which microorganism is commonly used in the production of bread and beer?
- A) Bacteria
- B) Protozoa
- C) Yeast
- D) Viruses
- Answer: C) Yeast
Which component of the bacterial cell wall is primarily responsible for its rigidity?
- A) Lipids
- B) Polysaccharides
- C) Peptidoglycan
- D) Nucleic acids
- Answer: C) Peptidoglycan
Which process describes the exchange of genetic material between two bacterial cells through direct contact?
- A) Transformation
- B) Transduction
- C) Conjugation
- D) Binary fission
- Answer: C) Conjugation
Which of the following is used to identify bacterial species based on their ability to ferment different sugars?
- A) Gram staining
- B) Biochemical tests
- C) PCR
- D) Electron microscopy
- Answer: B) Biochemical tests
Which type of microorganism can be classified as a cyanobacterium?
- A) Blue-green algae
- B) Protozoan
- C) Fungi
- D) Virus
- Answer: A) Blue-green algae
What is the primary role of ribosomes in cells?
- A) DNA replication
- B) Protein synthesis
- C) Energy production
- D) Cell division
- Answer: B) Protein synthesis
Which type of bacteria are characterized by a thick peptidoglycan layer in their cell walls?
- A) Gram-positive bacteria
- B) Gram-negative bacteria
- C) Acid-fast bacteria
- D) Mycoplasmas
- Answer: A) Gram-positive bacteria
Which disease is caused by the bacterium Vibrio cholerae?
- A) Tuberculosis
- B) Cholera
- C) Syphilis
- D) Leprosy
- Answer: B) Cholera
The primary function of bacterial capsules is:
- A) To aid in motility
- B) To protect against phagocytosis
- C) To help in DNA replication
- D) To facilitate cell division
- Answer: B) To protect against phagocytosis
Which of the following viruses is known for causing the common cold?
- A) Influenza virus
- B) Rhinovirus
- C) Hepatitis B virus
- D) Human immunodeficiency virus (HIV)
- Answer: B) Rhinovirus
Which process involves the transfer of genetic material from one bacterial cell to another via a bacteriophage?
- A) Conjugation
- B) Transduction
- C) Transformation
- D) Binary fission
- Answer: B) Transduction
Which bacterial structure is primarily involved in movement?
- A) Pili
- B) Capsule
- C) Flagella
- D) Endospore
- Answer: C) Flagella
Which type of microorganism is used in the production of antibiotics like penicillin?
- A) Bacteria
- B) Yeast
- C) Protozoa
- D) Fungi
- Answer: D) Fungi
Which of the following is an obligate intracellular parasite?
- A) Bacteria
- B) Protozoa
- C) Virus
- D) Fungi
- Answer: C) Virus
Which of the following is a method used to test for antibiotic susceptibility in bacteria?
- A) ELISA
- B) Gram staining
- C) Disk diffusion method
- D) PCR
- Answer: C) Disk diffusion method
Which term describes the ability of bacteria to take up free DNA from the environment?
- A) Conjugation
- B) Transduction
- C) Transformation
- D) Binary fission
- Answer: C) Transformation
Which bacterium is commonly associated with food poisoning from undercooked poultry?
- A) Salmonella enterica
- B) Staphylococcus aureus
- C) Escherichia coli
- D) Bacillus cereus
- Answer: A) Salmonella enterica
Which of the following is a non-pathogenic bacterium used in probiotic supplements?
- A) Escherichia coli
- B) Lactobacillus acidophilus
- C) Mycobacterium tuberculosis
- D) Vibrio cholerae
- Answer: B) Lactobacillus acidophilus
Which type of microscope is best suited for observing the detailed internal structures of a cell?
- A) Light microscope
- B) Scanning electron microscope
- C) Transmission electron microscope
- D) Fluorescence microscope
- Answer: C) Transmission electron microscope
Which disease is associated with the bacterium Clostridium tetani?
- A) Tetanus
- B) Tuberculosis
- C) Botulism
- D) Anthrax
- Answer: A) Tetanus
Which microorganism is used in the fermentation process to produce yogurt?
- A) Candida albicans
- B) Streptococcus thermophilus
- C) Escherichia coli
- D) Staphylococcus aureus
- Answer: B) Streptococcus thermophilus
Which type of virus has an RNA genome and is known to cause acquired immunodeficiency syndrome (AIDS)?
- A) DNA virus
- B) Retrovirus
- C) Herpesvirus
- D) Hepadnavirus
- Answer: B) Retrovirus
The use of antibiotics to control bacterial growth on surfaces is known as:
- A) Sterilization
- B) Disinfection
- C) Antisepsis
- D) Sanitization
- Answer: B) Disinfection
Which of the following bacterial structures is involved in the formation of endospores?
- A) Capsule
- B) Cell wall
- C) Cytoplasm
- D) Spore coat
- Answer: D) Spore coat
Which bacterial genus is known for its ability to form endospores and is used in the production of antibiotics?
- A) Bacillus
- B) Clostridium
- C) Staphylococcus
- D) Mycobacterium
- Answer: A) Bacillus
Which type of medium is selective for Gram-negative bacteria?
- A) Mannitol salt agar
- B) MacConkey agar
- C) Blood agar
- D) Nutrient agar
- Answer: B) MacConkey agar
Which microorganism is known for its role in nitrogen fixation in the soil?
- A) Rhizobium
- B) Bacillus
- C) Aspergillus
- D) Saccharomyces
- Answer: A) Rhizobium
Which process is used to kill all microorganisms, including spores, on surfaces?
- A) Disinfection
- B) Sterilization
- C) Sanitization
- D) Antisepsis
- Answer: B) Sterilization
Which of the following bacteria is a common cause of urinary tract infections (UTIs)?
- A) Staphylococcus epidermidis
- B) Escherichia coli
- C) Clostridium difficile
- D) Pseudomonas aeruginosa
- Answer: B) Escherichia coli
The primary function of bacterial pili is to:
- A) Aid in DNA replication
- B) Facilitate motility
- C) Enable adhesion to surfaces
- D) Produce toxins
- Answer: C) Enable adhesion to surfaces
Which of the following is a characteristic feature of viruses but not of bacteria?
- A) Presence of a cell wall
- B) Presence of ribosomes
- C) Presence of a nucleic acid genome
- D) Obligate intracellular parasitism
- Answer: D) Obligate intracellular parasitism
Which bacteria are known to cause infections in wounds and are often resistant to multiple antibiotics?
- A) Streptococcus pyogenes
- B) Staphylococcus aureus
- C) Bacillus anthracis
- D) Neisseria gonorrhoeae
- Answer: B) Staphylococcus aureus
Which term describes the process by which bacteria convert nitrate to nitrogen gas?
- A) Nitrogen fixation
- B) Nitrification
- C) Denitrification
- D) Ammonification
- Answer: C) Denitrification