Classification of viruses MCQs With Answer

Understanding the classification of viruses is essential for B.Pharm students preparing for pharmacology, microbiology, and virology exams. This SEO-friendly guide, “Classification of viruses MCQs With Answer”, offers focused revision on viral taxonomy, Baltimore classification, nucleic acid type (DNA/RNA), sense orientation, capsid symmetry, enveloped versus non-enveloped viruses, segmentation, host range and major viral families. Each MCQ reinforces concepts relevant to antiviral drug targets, vaccine design and diagnostics, helping students apply theory to practical pharmacy problems. Designed for exam-oriented study, these MCQs emphasize clinical relevance, antiviral mechanisms and laboratory classification techniques. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which classification system groups viruses based on their type of nucleic acid and replication strategy?

• Baltimore classification
• Linnaean taxonomy
• Gram classification
• Morphological classification only

Correct Answer: Baltimore classification

Q2. Which Baltimore group contains double-stranded DNA viruses that replicate in the nucleus?

• Group I
• Group IV
• Group V
• Group VII

Correct Answer: Group I

Q3. Which feature primarily distinguishes enveloped from non-enveloped viruses?

• Presence of a lipid membrane surrounding the capsid
• Type of nucleic acid (DNA vs RNA)
• Capsid symmetry being always helical
• Ability to infect bacteria only

Correct Answer: Presence of a lipid membrane surrounding the capsid

Q4. Positive-sense single-stranded RNA viruses are characterized by which property?

• Their genome can act directly as mRNA
• Their genome must be transcribed into mRNA by host enzymes
• They always possess a DNA intermediate
• They integrate into the host genome as provirus

Correct Answer: Their genome can act directly as mRNA

Q5. Which family is an example of a non-enveloped, positive-sense RNA virus important in human disease?

• Picornaviridae
• Orthomyxoviridae
• Herpesviridae
• Flaviviridae

Correct Answer: Picornaviridae

Q6. What distinguishes Group V viruses in the Baltimore classification?

• Negative-sense single-stranded RNA genomes
• Double-stranded DNA genomes
• Positive-sense single-stranded RNA genomes
• Double-stranded RNA segmented genomes

Correct Answer: Negative-sense single-stranded RNA genomes

Q7. Which virus family contains segmented, negative-sense RNA genomes and causes seasonal influenza?

• Orthomyxoviridae
• Paramyxoviridae
• Picornaviridae
• Caliciviridae

Correct Answer: Orthomyxoviridae

Q8. Which viral structural symmetry is typical of many animal viruses such as adenovirus?

• Icosahedral symmetry
• Helical symmetry only
• Filamentous complex symmetry
• No capsid structure

Correct Answer: Icosahedral symmetry

Q9. Reassortment (antigenic shift) in influenza viruses requires which genomic feature?

• Segmented genome
• Single circular DNA genome
• Genome replication in the nucleus only
• Stable DNA intermediate

Correct Answer: Segmented genome

Q10. Which virus family uses reverse transcriptase despite having a DNA genome that replicates via an RNA intermediate?

• Hepadnaviridae
• Herpesviridae
• Adenoviridae
• Parvoviridae

Correct Answer: Hepadnaviridae

Q11. Which method is commonly used to visualize viral particles and determine morphology for classification?

• Transmission electron microscopy
• Light microscopy with Gram stain
• Centrifugation without imaging
• ELISA without imaging

Correct Answer: Transmission electron microscopy

Q12. Which RNA virus family is known for double-stranded segmented RNA genomes and includes rotaviruses?

• Reoviridae
• Flaviviridae
• Retroviridae
• Picornaviridae

Correct Answer: Reoviridae

Q13. Which classification authority is responsible for standardized virus taxonomy?

• International Committee on Taxonomy of Viruses (ICTV)
• World Health Organization only
• Centers for Disease Control and Prevention
• International Union for Conservation of Nature

Correct Answer: International Committee on Taxonomy of Viruses (ICTV)

Q14. Which viral feature most directly determines host cell tropism?

• Interaction between viral surface proteins and host cell receptors
• Viral genome length only
• Capsid symmetry exclusively
• Viral buoyant density

Correct Answer: Interaction between viral surface proteins and host cell receptors

Q15. Which family includes enveloped viruses with positive-sense RNA and includes dengue and Zika viruses?

• Flaviviridae
• Retroviridae
• Adenoviridae
• Paramyxoviridae

Correct Answer: Flaviviridae

Q16. Which of the following is a characteristic of picornaviruses relevant to stability and transmission?

• Non-enveloped and resistant to detergents
• Enveloped and easily inactivated by alcohol
• Always segmented genomes
• Require insect vectors exclusively

Correct Answer: Non-enveloped and resistant to detergents

Q17. Which viral enzyme synthesizes RNA from an RNA template and is a hallmark of many RNA viruses?

• RNA-dependent RNA polymerase
• DNA-dependent RNA polymerase
• Reverse transcriptase only found in DNA viruses
• Topoisomerase

Correct Answer: RNA-dependent RNA polymerase

Q18. Which family includes retroviruses that integrate into the host genome as a provirus?

• Retroviridae
• Coronaviridae
• Herpesviridae
• Parvoviridae

Correct Answer: Retroviridae

Q19. Which diagnostic assay quantifies infectious viral titer by visible plaques on cell monolayers?

• Plaque assay
• Western blot
• Hemagglutination assay
• PCR without culture

Correct Answer: Plaque assay

Q20. Which family contains large, complex enveloped DNA viruses that replicate in the cytoplasm and include variola virus?

• Poxviridae
• Herpesviridae
• Adenoviridae
• Papillomaviridae

Correct Answer: Poxviridae

Q21. Which viral genome type is characteristic of parvoviruses?

• Single-stranded DNA (ssDNA)
• Double-stranded RNA (dsRNA)
• Positive-sense RNA
• Segmented negative-sense RNA

Correct Answer: Single-stranded DNA (ssDNA)

Q22. Antigenic drift in influenza results from what molecular process?

• Accumulation of point mutations in surface glycoprotein genes
• Genome reassortment between strains
• Complete genome replacement by recombination with bacteria
• Loss of envelope lipids

Correct Answer: Accumulation of point mutations in surface glycoprotein genes

Q23. Which viral family contains enveloped, positive-sense RNA viruses with a characteristic crown-like appearance under EM?

• Coronaviridae
• Paramyxoviridae
• Caliciviridae
• Rhabdoviridae

Correct Answer: Coronaviridae

Q24. Which enzyme is the molecular target of nucleoside reverse transcriptase inhibitors used against HIV?

• Reverse transcriptase
• RNA-dependent RNA polymerase
• DNA gyrase
• Neuraminidase

Correct Answer: Reverse transcriptase

Q25. Which viral process is directly inhibited by neuraminidase inhibitors like oseltamivir?

• Viral release from host cells
• Viral DNA replication in the nucleus
• Capsid assembly in the cytoplasm
• Attachment to host cell receptors only

Correct Answer: Viral release from host cells

Q26. Which viral classification level comes directly above ‘genus’?

• Family
• Species
• Order
• Subfamily

Correct Answer: Family

Q27. Which viral genome property allows retroviruses to be diploid (contain two RNA molecules)?

• Packaging of two copies of positive-sense RNA genome per virion
• Double-stranded DNA genome with introns
• Segmented negative-sense RNA genome
• Serial integration into host chromosomes

Correct Answer: Packaging of two copies of positive-sense RNA genome per virion

Q28. Which laboratory assay measures the ability of viruses to agglutinate red blood cells and is used in influenza typing?

• Hemagglutination assay
• Neutralization PCR
• Western blot assay
• Complement fixation alone

Correct Answer: Hemagglutination assay

Q29. Which virus family includes DNA viruses that establish latent infections in humans and have icosahedral capsids?

• Herpesviridae
• Retroviridae
• Flaviviridae
• Rhabdoviridae

Correct Answer: Herpesviridae

Q30. Which classification criterion is most useful when predicting susceptibility to disinfectants?

• Presence or absence of a lipid envelope
• Capsid symmetry only
• Genome GC content
• Virus particle size only

Correct Answer: Presence or absence of a lipid envelope

Q31. Which mechanism leads to genetic recombination in RNA viruses during co-infection?

• Template switching during RNA replication
• Antigenic drift only
• DNA integration into host genome exclusively
• Capsid exchange between virions

Correct Answer: Template switching during RNA replication

Q32. Which property best describes adenoviruses relevant to classification and vaccine use?

• Non-enveloped dsDNA viruses used as vaccine vectors
• Enveloped negative-strand RNA viruses used as live vaccines
• Retroviruses integrating as proviruses in gene therapy only
• Single-stranded RNA plant viruses not relevant to humans

Correct Answer: Non-enveloped dsDNA viruses used as vaccine vectors

Q33. Which viral family is a major cause of oncogenic transformation in humans (e.g., cervical cancer)?

• Papillomaviridae
• Orthomyxoviridae
• Paramyxoviridae
• Picornaviridae

Correct Answer: Papillomaviridae

Q34. Which of the following is TRUE about RNA viruses in terms of mutation rate?

• They generally have higher mutation rates due to lack of proofreading by viral polymerases
• They always have lower mutation rates than DNA viruses
• Mutation rates are negligible because host enzymes proofread viral RNA
• RNA viruses never undergo antigenic drift

Correct Answer: They generally have higher mutation rates due to lack of proofreading by viral polymerases

Q35. Which virus family includes enveloped, bullet-shaped viruses and causes rabies?

• Rhabdoviridae
• Filoviridae
• Paramyxoviridae
• Flaviviridae

Correct Answer: Rhabdoviridae

Q36. Which viral classification group includes double-stranded RNA viruses according to Baltimore?

• Group III
• Group II
• Group IV
• Group VI

Correct Answer: Group III

Q37. Which family of bacteriophages is known for long, noncontractile tails and is commonly used in phage research?

• Siphoviridae
• Myoviridae
• Podoviridae
• Flaviviridae

Correct Answer: Siphoviridae

Q38. Which feature is characteristic of viral ‘complex’ symmetry exemplified by poxviruses?

• Irregular or complex capsid not purely icosahedral or helical
• Perfect icosahedral symmetry only
• Filamentous helical capsid exclusively
• No capsid or envelope present

Correct Answer: Irregular or complex capsid not purely icosahedral or helical

Q39. Which class of vaccines contains whole viruses that have been inactivated to prevent replication?

• Inactivated (killed) vaccines
• Live attenuated vaccines
• Subunit vaccines only
• mRNA vaccines that always replicate

Correct Answer: Inactivated (killed) vaccines

Q40. Which viral property best explains why some viruses are transmitted via fecal-oral route?

• Non-enveloped capsid conferring environmental stability
• Presence of a fragile lipid envelope
• Requirement for insect vectors exclusively
• Large genome size only

Correct Answer: Non-enveloped capsid conferring environmental stability

Q41. Which virus genus includes agents that are small, non-enveloped, positive-sense RNA viruses causing gastroenteritis (e.g., Norwalk virus)?

• Norovirus (Caliciviridae)
• Orthomyxovirus (Orthomyxoviridae)
• Enterovirus (Picornaviridae)
• Flavivirus (Flaviviridae)

Correct Answer: Norovirus (Caliciviridae)

Q42. Which mechanism differentiates lytic and lysogenic cycles in bacteriophages?

• Whether the phage genome integrates into the host chromosome or replicates independently and lyses the cell
• Only the size of the phage capsid
• Whether the phage infects Gram-positive versus Gram-negative bacteria
• Presence of an envelope in the phage particle

Correct Answer: Whether the phage genome integrates into the host chromosome or replicates independently and lyses the cell

Q43. Which viral family includes single-stranded negative-sense RNA viruses that commonly cause respiratory infections in children (e.g., RSV)?

• Paramyxoviridae
• Picornaviridae
• Flaviviridae
• Caliciviridae

Correct Answer: Paramyxoviridae

Q44. Which viral diagnostic technique amplifies and detects viral nucleic acid rapidly and is widely used in classification and detection?

• Polymerase chain reaction (PCR)
• Hemagglutination only
• Plaque assay for antibodies
• ELISA for genome sequencing

Correct Answer: Polymerase chain reaction (PCR)

Q45. Which concept explains why influenza A viruses can give rise to pandemics through major antigenic changes?

• Reassortment between different influenza A strains (antigenic shift)
• Gradual point mutations only (antigenic drift)
• Loss of envelope making them more stable
• Integration into the human genome as provirus

Correct Answer: Reassortment between different influenza A strains (antigenic shift)

Q46. Which viral family includes hepatitis B virus, a DNA virus that replicates via an RNA intermediate?

• Hepadnaviridae
• Hepadnaviridae is incorrect; it’s an RNA virus
• Picornaviridae
• Retroviridae only

Correct Answer: Hepadnaviridae

Q47. Which viral structural protein composes the outer protein shell that encloses the genome?

• Capsid protein
• Polymerase protein only
• Ribosomal proteins
• Host histones always

Correct Answer: Capsid protein

Q48. Which of the following is a key distinction between DNA and RNA virus classification relevant to replication fidelity?

• DNA viruses generally have higher replication fidelity due to proofreading mechanisms
• RNA viruses always replicate with host DNA polymerase fidelity
• DNA viruses never integrate into host genomes
• RNA viruses always replicate in the nucleus and use host proofreading

Correct Answer: DNA viruses generally have higher replication fidelity due to proofreading mechanisms

Q49. Which viral family includes single-stranded positive-sense RNA viruses with enveloped particles and long spike proteins, responsible for severe hemorrhagic fevers (e.g., Ebola)?

• Filoviridae
• Flaviviridae
• Bunyaviridae
• Caliciviridae

Correct Answer: Filoviridae

Q50. Which property is most important when selecting a viral vector for gene therapy to ensure long-term expression in dividing cells?

• Ability to integrate into the host genome (e.g., lentiviral vectors)
• Non-integrating single-stranded RNA vectors only
• Large envelope size regardless of integration
• Inability to enter the nucleus

Correct Answer: Ability to integrate into the host genome (e.g., lentiviral vectors)

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com