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 3 of 3
- A. Mycoplasma
- B. Corynebacterium
- C. Bordetella
- D. Erysipelothrix
Explanation: Mycoplasma species lack the peptidoglycan cell wall targeted by penicillin and related beta-lactam drugs.
Correct answer: Mycoplasma- A. Ziehl-Neelsen staining
- B. India ink preparation
- C. Albert staining
- D. Giemsa staining
Explanation: India ink provides a dark background against which the unstained capsule appears as a clear halo around the bacterial cell.
Correct answer: India ink preparation- A. Escherichia coli
- B. Salmonella enterica
- C. Listeria monocytogenes
- D. Staphylococcus aureus
Explanation: Listeria monocytogenes displays tumbling motility at room temperature because of its temperature-dependent flagellar activity.
Correct answer: Listeria monocytogenes- A. Detergents remove their capsid genes
- B. Detergents destroy their viral DNA
- C. Detergents block their ribosomes
- D. Detergents disrupt their lipid envelope
Explanation: The envelope is a lipid membrane that is disrupted by detergents, causing loss of viral infectivity.
Correct answer: Detergents disrupt their lipid envelope- A. Cat
- B. Dog
- C. Sheep
- D. Horse
Explanation: Felids, including domestic cats, are the definitive hosts in which Toxoplasma gondii undergoes sexual reproduction and produces oocysts.
Correct answer: Cat- A. Ixodes hard tick
- B. Culicoides biting midge
- C. Sarcoptes mite
- D. Anopheles mosquito
Explanation: Bluetongue virus is transmitted biologically by female Culicoides midges, especially species in the C.
Correct answer: Culicoides biting midge- A. Schick test
- B. Rose Bengal test
- C. Coggins test
- D. Widal test
Explanation: The Coggins test is an agar gel immunodiffusion test used to detect antibodies against equine infectious anaemia virus.
Correct answer: Coggins test- A. Bone marrow
- B. Spleen
- C. Lymph node
- D. Thymus
Explanation: Immature T lymphocytes migrate to the thymus, where they undergo selection and mature into functional T cells.
Correct answer: Thymus- A. Microbial antigen in the sample
- B. Serum antibody against the microbe
- C. Bacterial toxin in urine
- D. Host complement concentration
Explanation: In a direct fluorescent antibody test, a fluorescently labelled antibody binds directly to microbial antigen in cells or tissue.
Correct answer: Microbial antigen in the sample- A. Dry heat sterilization
- B. Membrane filtration
- C. Flaming over a burner
- D. Boiling for ten minutes
Explanation: Membrane filtration removes bacteria from heat-sensitive liquids without exposing the serum to damaging temperatures.
Correct answer: Membrane filtration- A. Teichoic acid layer
- B. Thick peptidoglycan layer
- C. Lipopolysaccharide layer
- D. Chitinous cell wall
Explanation: Lipopolysaccharide is a major component of the outer membrane of Gram-negative bacteria and includes lipid A, core polysaccharide, and O…
Correct answer: Lipopolysaccharide layer- A. Acid-fast mycobacteria
- B. Strictly anaerobic bacteria
- C. Dermatophyte fungi
- D. Gram-negative enteric bacteria
Explanation: MacConkey agar contains substances that inhibit many Gram-positive organisms, allowing Gram-negative enteric bacteria to grow.
Correct answer: Gram-negative enteric bacteria- A. Incubation in an anaerobic system
- B. Incubation in a candle jar
- C. Incubation in ordinary air
- D. Incubation under ultraviolet light
Explanation: Obligate anaerobes require an atmosphere in which oxygen is removed or greatly reduced, such as an anaerobic jar or chamber.
Correct answer: Incubation in an anaerobic system- A. Denaturation
- B. Annealing
- C. Extension
- D. Elution
Explanation: Annealing is the stage when primers attach to their complementary sequences on the separated DNA strands.
Correct answer: Annealing55. Which bacterial enzyme is responsible for synthesizing new DNA strands during a standard PCR cycle?
- A. Reverse transcriptase
- B. RNA polymerase
- C. Taq DNA polymerase
- D. DNA ligase
Explanation: Taq DNA polymerase extends primers and synthesizes new DNA during PCR, while remaining active through repeated heating cycles.
Correct answer: Taq DNA polymerase- A. Spirochetal disease
- B. Rickettsial disease
- C. Protozoal disease
- D. Prion disease
Explanation: Prion diseases result from abnormal infectious proteins that induce misfolding of normal host proteins.
Correct answer: Prion disease- A. They neutralize vaccine antigens before immune priming
- B. They destroy the animal's lymph nodes
- C. They permanently block antibody production
- D. They convert live vaccines into bacterial toxins
Explanation: Passively acquired maternal antibodies may bind and neutralize vaccine antigens before the young animal mounts an adequate active immune…
Correct answer: They neutralize vaccine antigens before immune priming- A. Natural passive immunity
- B. Natural active immunity
- C. Artificial passive immunity
- D. Innate barrier immunity
Explanation: Recovery from infection stimulates the animal to produce its own antibodies and memory lymphocytes, which is natural active immunity.
Correct answer: Natural active immunity- A. Opsonization
- B. Antigenic variation
- C. Immune tolerance
- D. Complement fixation
Explanation: Immune tolerance prevents harmful responses against the body's own antigens by deleting or inactivating self-reactive lymphocytes.
Correct answer: Immune tolerance- A. A parasitic adult worm
- B. A whole bacterial cell
- C. A viral envelope
- D. A soluble protein
Explanation: Precipitation occurs when soluble antigens react with their specific antibodies and form an insoluble lattice.
Correct answer: A soluble protein