Free Veterinary Microbiology and Immunology MCQs with Answers
60 Veterinary Microbiology and Immunology MCQs from Veterinary Science, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Covers the structure, classification, growth and transmission of bacteria, viruses, fungi and other disease causing microorganisms in animals. It explains innate and acquired immunity, antibodies, antigens, vaccination, hypersensitivity and diagnostic methods, while distinguishing infectious agents from the immune responses they produce.
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60 questions · page 2 of 3
- A. Transduction
- B. Conjugation
- C. Transformation
- D. Transposition
Explanation: Transduction occurs when a bacteriophage carries bacterial DNA from one cell to another.
Correct answer: Transduction- A. Corynebacterium pseudotuberculosis
- B. Pasteurella multocida
- C. Erysipelothrix rhusiopathiae
- D. Listeria monocytogenes
Explanation: Pasteurella multocida may show bipolar staining, giving a safety-pin appearance with suitable stains.
Correct answer: Pasteurella multocida- A. Neurotoxin
- B. Enterotoxin B
- C. Phospholipase C
- D. Botulinum toxin
Explanation: Clostridium perfringens type A produces alpha toxin, which is phospholipase C and damages cell membranes.
Correct answer: Phospholipase C- A. Conjugation
- B. Transduction
- C. Translocation
- D. Transformation
Explanation: Transformation is the acquisition of free DNA from the environment by a competent bacterial cell.
Correct answer: Transformation- A. Bursa of Fabricius
- B. Spleen
- C. Thymus
- D. Cecal tonsil
Explanation: The bursa of Fabricius is the major site of B-cell development in birds.
Correct answer: Bursa of Fabricius- A. C1q
- B. C3b
- C. C5a
- D. C9
Explanation: C3b binds to microbial surfaces and promotes their recognition and phagocytosis by immune cells.
Correct answer: C3b- A. Mannose on a microbial surface
- B. Bacterial lipopolysaccharide alone
- C. Antigen-bound antibody
- D. Spontaneous C3 hydrolysis
Explanation: The classical pathway begins when C1 binds to antibody, usually IgM or IgG, attached to an antigen.
Correct answer: Antigen-bound antibody- A. Basophils
- B. Erythrocytes
- C. Naive B cells
- D. Natural killer cells
Explanation: Natural killer cells bind the Fc portion of target-bound IgG through CD16 and then release cytotoxic granules.
Correct answer: Natural killer cells29. Which culture medium is commonly used for the isolation of dermatophytes from animal skin and hair?
- A. Sabouraud dextrose agar
- B. MacConkey agar
- C. Lowenstein-Jensen medium
- D. Thayer-Martin medium
Explanation: Sabouraud dextrose agar is acidic and supports the growth of fungi, including dermatophytes.
Correct answer: Sabouraud dextrose agar- A. Destroy vaccine antigen rapidly
- B. Enhance and prolong the immune response
- C. Replace the need for antigen
- D. Prevent all local inflammation
Explanation: Adjuvants improve antigen presentation and stimulate a stronger, longer-lasting immune response to nonreplicating vaccine antigens.
Correct answer: Enhance and prolong the immune response- A. Ribosome
- B. Flagellum
- C. Capsule
- D. Plasmid
Explanation: A capsule can prevent effective attachment and engulfment by phagocytic cells, increasing bacterial survival in tissues.
Correct answer: Capsule32. Which condition is commonly used for sterilizing heat-stable laboratory instruments in an autoclave?
- A. 100°C at normal pressure
- B. 80°C at reduced pressure
- C. 160°C with dry air
- D. 121°C at 15 psi
Explanation: Steam under pressure at about 121°C and 15 psi destroys vegetative bacteria, viruses, fungi, and bacterial spores when applied for…
Correct answer: 121°C at 15 psi- A. Neutralize microbes at mucosal surfaces
- B. Activate red blood cell production
- C. Cause systemic mast-cell degranulation
- D. Destroy infected cells through complement
Explanation: Secretory IgA binds microbes and toxins at mucosal surfaces, limiting their attachment and entry without causing extensive inflammation.
Correct answer: Neutralize microbes at mucosal surfaces- A. Lipopolysaccharide
- B. Calcium dipicolinate
- C. Hyaluronic acid
- D. Teichoic acid
Explanation: Calcium dipicolinate, together with the dehydrated spore core, contributes substantially to the exceptional resistance of bacterial…
Correct answer: Calcium dipicolinate- A. Immediate IgE-mediated allergy
- B. Circulating bacterial endotoxin
- C. Delayed cellular hypersensitivity
- D. Neutralizing serum antibody
Explanation: The tuberculin test measures a delayed-type cellular immune response to mycobacterial antigens, usually becoming evident after local skin…
Correct answer: Delayed cellular hypersensitivity- A. Binary fission
- B. Transduction
- C. Transformation
- D. Conjugation
Explanation: Conjugation transfers DNA, commonly through a pilus, from a donor bacterium to a recipient in direct contact.
Correct answer: Conjugation- A. Memory B and T lymphocytes
- B. Mature erythrocytes
- C. Neutrophil granules
- D. Plasma complement proteins
Explanation: Antigen exposure produces memory B and T cells that persist after the initial response and react rapidly upon later exposure.
Correct answer: Memory B and T lymphocytes- A. Coagulase test
- B. Agglutination test
- C. Oxidase test
- D. Catalase test
Explanation: Agglutination tests detect visible clumping produced when antibodies cross-link particulate antigens.
Correct answer: Agglutination test- A. Canine infectious hepatitis
- B. Canine parvoviral enteritis
- C. Canine distemper
- D. Canine adenovirus cough
Explanation: Canine distemper virus can cause respiratory and gastrointestinal disease, neurological signs, and hyperkeratosis of the footpads.
Correct answer: Canine distemper- A. Replicate rapidly in host tissues
- B. Cannot be recognized by antibodies
- C. Always cause severe local disease
- D. Provide weaker stimulation of cellular immunity
Explanation: Killed organisms cannot replicate and often produce a weaker or shorter immune response, so an adjuvant can enhance antigen presentation…
Correct answer: Provide weaker stimulation of cellular immunity