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 1 of 3
1. Which laboratory test most reliably differentiates Staphylococcus aureus from Streptococcus species?
- A. Catalase test
- B. Oxidase test
- C. Indole test
- D. Urease test
Explanation: Staphylococcus aureus is catalase positive, whereas Streptococcus species are catalase negative.
Correct answer: Catalase test- A. O antigen
- B. Lipid A
- C. Core polysaccharide
- D. Capsular polysaccharide
Explanation: Lipid A is the toxic portion of lipopolysaccharide in the outer membrane of Gram-negative bacteria.
Correct answer: Lipid A- A. C1 through C4
- B. C3a and C5a
- C. C5b through C9
- D. Factor B and properdin
Explanation: The membrane attack complex consists of C5b, C6, C7, C8 and multiple C9 molecules.
Correct answer: C5b through C9- A. IgA
- B. IgE
- C. IgM
- D. IgG
Explanation: IgG is the most abundant immunoglobulin in serum and provides important systemic and long-term antibody protection.
Correct answer: IgG- A. Mycolic acids
- B. Teichoic acids
- C. Lipoteichoic acids
- D. Hyaluronic acid
Explanation: Mycolic acids are long-chain fatty acids in the mycobacterial cell wall and retain the primary stain during acid-fast staining.
Correct answer: Mycolic acids6. In cattle and sheep, antibodies transferred from the dam to the newborn are obtained mainly through:
- A. Placental blood transfer
- B. Colostrum consumption
- C. Amniotic fluid ingestion
- D. Milk produced after weaning
Explanation: Ruminants have a syndesmochorial placenta that allows little or no prenatal transfer of immunoglobulins.
Correct answer: Colostrum consumption- A. MHC II with CD8-positive T cells
- B. MHC I with CD4-positive T cells
- C. MHC I with CD8-positive T cells
- D. MHC II with B lymphocytes
Explanation: MHC I molecules present intracellular antigens to CD8-positive cytotoxic T cells.
Correct answer: MHC I with CD8-positive T cells- A. Canine distemper virus
- B. Bovine viral diarrhoea virus
- C. Feline calicivirus
- D. Rabies virus
Explanation: Negri bodies are eosinophilic cytoplasmic inclusions found particularly in neurons infected with rabies virus.
Correct answer: Rabies virus- A. Type I hypersensitivity
- B. Type II hypersensitivity
- C. Type III hypersensitivity
- D. Type IV hypersensitivity
Explanation: Type I hypersensitivity is an immediate allergic reaction involving IgE bound to mast cells, followed by mediator release after…
Correct answer: Type I hypersensitivity- A. It produces no cellular immunity
- B. It often induces strong humoral and cellular immunity
- C. It cannot replicate in the vaccinated host
- D. It always remains safe in pregnant animals
Explanation: Live attenuated vaccines usually replicate to a limited extent and stimulate both antibody-mediated and cellular immune responses.
Correct answer: It often induces strong humoral and cellular immunity- A. A thin peptidoglycan layer
- B. An outer lipopolysaccharide membrane
- C. A thick peptidoglycan layer
- D. A capsule rich in polysaccharides
Explanation: Gram-positive bacteria have a thick peptidoglycan layer that traps the crystal violet iodine complex during decolorization.
Correct answer: A thick peptidoglycan layer- A. Lag phase
- B. Death phase
- C. Stationary phase
- D. Logarithmic phase
Explanation: The logarithmic, or exponential, phase is marked by rapid and regular cell division.
Correct answer: Logarithmic phase- A. Tetanospasmin
- B. Botulinum toxin
- C. Staphylococcal enterotoxin
- D. Cholera toxin
Explanation: Tetanospasmin is the neurotoxin produced by Clostridium tetani and causes spastic paralysis by blocking inhibitory neurotransmission.
Correct answer: Tetanospasmin- A. Respiratory mucosa
- B. Digestive or genital mucosa
- C. Intact skin surface
- D. Central nervous system
Explanation: Brucella abortus commonly enters through the digestive or genital mucosa, especially after contact with contaminated fetal membranes…
Correct answer: Digestive or genital mucosa- A. A nonsegmented RNA genome
- B. A double-stranded DNA genome
- C. A segmented RNA genome
- D. A lipid-free protein capsid
Explanation: Influenza viruses possess a segmented RNA genome, so two strains infecting the same cell can exchange genome segments.
Correct answer: A segmented RNA genome- A. Protozoal multiplication in erythrocytes
- B. Viral replication in neurons
- C. Bacterial growth in muscle tissue
- D. Keratin invasion by fungal hyphae
Explanation: Dermatophytes grow in keratinized tissues such as the skin, hair, and nails, producing superficial circular lesions.
Correct answer: Keratin invasion by fungal hyphae- A. Antigen-antibody immune complexes
- B. IgE-coated mast cells
- C. Sensitized T lymphocytes
- D. Cytotoxic natural killer cells
Explanation: Type III hypersensitivity results from circulating antigen-antibody complexes depositing in tissues and activating inflammation.
Correct answer: Antigen-antibody immune complexes- A. IgA
- B. IgM
- C. IgG
- D. IgE
Explanation: IgM is generally the first immunoglobulin released during a primary immune response.
Correct answer: IgM- A. Viral shape by microscopy
- B. Bacterial motility in culture
- C. Antibody in the serum sample
- D. Antibiotic concentration in tissues
Explanation: An indirect ELISA commonly detects antibodies in a serum sample by using an enzyme-labelled secondary antibody.
Correct answer: Antibody in the serum sample- A. Erythropoietin
- B. Histamine
- C. Bradykinin
- D. Interferon
Explanation: Interferons, especially type I interferons, stimulate antiviral mechanisms in infected and neighboring cells and help activate natural…
Correct answer: InterferonVeterinary Microbiology and Immunology MCQs: common questions
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There are 60 Veterinary Microbiology and Immunology MCQs in the Veterinary Science bank, shown 20 to a page with the correct answer and an explanation on each.
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Yes. Each Veterinary Microbiology and Immunology question shows the correct option and a written explanation of why it is correct, so a wrong answer teaches you something rather than just being marked wrong.
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