Laboratory animals: species, strains, description and applications MCQs With Answer

Laboratory animals: species, strains, description and applications MCQs With Answer

Laboratory animals are indispensable tools in M.Pharm training, research, and preclinical drug development. This blog provides focused multiple-choice questions on common laboratory species and strains, their distinguishing characteristics, and typical pharmacological and toxicological applications. Questions cover rodents and non-rodents, inbred and outbred strains, immunodeficient and transgenic models, and practical selection criteria for specific experimental needs. Each MCQ includes concise options and correct answers to help you assess and strengthen knowledge required for experimental design, regulatory compliance, and interpretation of preclinical data. Use these questions to prepare for exams, viva voce, and to deepen understanding of animal models in drug screening and safety assessment.

Q1. Which laboratory animal species is most widely used in biomedical research due to its small size, rapid breeding, and extensive genetic tools?

• Dog (Canis familiaris)
• Mouse (Mus musculus)
• Rabbit (Oryctolagus cuniculus)
• Guinea pig (Cavia porcellus)

Correct Answer: Mouse (Mus musculus)

Q2. What term best describes a strain produced by at least 20 consecutive generations of brother–sister mating resulting in near genetic homogeneity?

• Outbred strain
• Congenic strain
• Inbred strain
• Hybrid strain

Correct Answer: Inbred strain

Q3. Which rat strain is commonly used in toxicology and pharmacology studies because of its docile nature and well-characterized physiology?

• Siamese rat
• Sprague-Dawley rat
• Wistar Kyoto rat exclusively
• Long-Evans hooded rat exclusively

Correct Answer: Sprague-Dawley rat

Q4. Which characteristic is typical of the BALB/c mouse strain relevant to immunological studies?

• Strong Th1-biased immune responses
• High spontaneous tumor incidence only
• Th2-biased immune responses and suitability for antibody production
• Extreme resistance to infectious agents

Correct Answer: Th2-biased immune responses and suitability for antibody production

Q5. Which statement best describes the C57BL/6 mouse strain commonly used in research?

• Albino, outbred, rarely used for genetics
• Black coat, inbred, widely used for transgenic and immunology studies
• Immunodeficient and used primarily for xenografts
• Large-bodied rat strain mistakenly called a mouse

Correct Answer: Black coat, inbred, widely used for transgenic and immunology studies

Q6. What is the primary immunological defect in athymic “nude” mice that makes them useful for human tumor xenografts?

• Complement deficiency
• Lack of mature T lymphocytes due to absence of a thymus
• Excessive NK cell activity
• Overproduction of antibodies

Correct Answer: Lack of mature T lymphocytes due to absence of a thymus

Q7. Severe Combined Immunodeficiency (SCID) mice are characterized by which of the following?

• Only B-cell deficiency with normal T cells
• Defects in both B and T lymphocyte function
• Only neutrophil dysfunction
• Enhanced adaptive immune responses

Correct Answer: Defects in both B and T lymphocyte function

Q8. Which description defines an outbred laboratory strain?

• Derived from repeated brother–sister mating to achieve homozygosity
• Genetically heterogeneous population maintained to preserve variability
• Produced by targeted gene deletion
• Always immunodeficient

Correct Answer: Genetically heterogeneous population maintained to preserve variability

Q9. What is a congenic strain?

• A strain that is completely unrelated genetically to its donor
• An outbred stock used for general screening
• A strain produced by backcrossing a genetic locus onto a defined background for multiple generations
• A strain produced by chemical mutagenesis only

Correct Answer: A strain produced by backcrossing a genetic locus onto a defined background for multiple generations

Q10. Which statement correctly differentiates a transgenic animal from a knockout animal?

• Transgenic animals have a targeted gene deletion; knockouts carry extra copies of a gene
• Transgenic animals carry an introduced foreign gene; knockouts have a specific gene inactivated or deleted
• Both terms are interchangeable
• Knockouts always overexpress the target gene

Correct Answer: Transgenic animals carry an introduced foreign gene; knockouts have a specific gene inactivated or deleted

Q11. When selecting an animal model for a pharmacological study, which criterion is most critical?

• Availability of the species in the local pet store
• Similarity of model pathology and physiology to the human condition under study
• Colour of the animal’s fur
• Historical use only without validation

Correct Answer: Similarity of model pathology and physiology to the human condition under study

Q12. In toxicology, what does LD50 refer to?

• The dose at which 50% of the population shows therapeutic benefit
• The dose that is lethal to 50% of a test population under defined conditions
• The lowest dose tested in an experiment
• A measure of drug potency in vitro only

Correct Answer: The dose that is lethal to 50% of a test population under defined conditions

Q13. Which advantage makes zebrafish a useful non-mammalian model in drug screening?

• Very long generation time compared with mice
• Transparent embryos and rapid external development suitable for high-throughput screening
• High maintenance costs and requirement for complex diets
• Inability to model vertebrate developmental processes

Correct Answer: Transparent embryos and rapid external development suitable for high-throughput screening

Q14. For which application are rabbits commonly used in pharmacology and toxicology?

• Primary use as a model for murine viral infections exclusively
• Antibody production and ocular irritation studies
• In vivo transgenic knockout generation
• Routine gene-targeting work as in mice

Correct Answer: Antibody production and ocular irritation studies

Q15. Which nutritional requirement is distinctive for guinea pigs compared to many other laboratory rodents?

• Requirement for dietary vitamin C because they cannot synthesize it
• Obligate carnivory requiring raw meat diet
• Resistance to all dietary deficiencies
• No special dietary requirements beyond basic rodent chow

Correct Answer: Requirement for dietary vitamin C because they cannot synthesize it

Q16. What unique anatomical feature of the Syrian (golden) hamster is exploited in oral and cancer research?

• Multi-chambered stomach like ruminants
• Cheek pouch that is an immunologically privileged site for tumor grafting
• Absence of salivary glands
• Complete lack of lymphoid tissues

Correct Answer: Cheek pouch that is an immunologically privileged site for tumor grafting

Q17. Regulatory toxicology guidelines typically require preclinical safety testing in which combination of species?

• Two rodent species only
• One rodent species and one non-rodent species
• Only non-rodent species are acceptable
• Any single species is sufficient if well characterized

Correct Answer: One rodent species and one non-rodent species

Q18. What does SPF mean in the context of animal colonies?

• Single-pair family breeding
• Specific Pathogen Free, indicating animals are free of defined pathogens
• Standard physiological format
• Simple population founder

Correct Answer: Specific Pathogen Free, indicating animals are free of defined pathogens

Q19. Which definition best fits gnotobiotic animals?

• Animals kept in complete darkness for experiments
• Animals with a known and defined microbial status, including germ-free or colonized with defined flora
• Wild-caught animals used without acclimatization
• Animals with spontaneous infections used for pathogenesis studies

Correct Answer: Animals with a known and defined microbial status, including germ-free or colonized with defined flora

Q20. What is the purpose of using sentinel animals in an animal facility health surveillance program?

• To increase colony numbers rapidly
• To monitor pathogen presence by exposure to soiled bedding and subsequent diagnostic testing
• To act as breeding stock only
• To replace immunodeficient models in research

Correct Answer: To monitor pathogen presence by exposure to soiled bedding and subsequent diagnostic testing

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