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NEET Biology: Viruses and Viroids Practice Questions

15 free multiple-choice questions on Viruses and Viroids (Diversity in Living World) for NEET Biology, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.

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  1. Q1. The structure that encloses the genetic material of a virus and is composed of protein is called the:

    • ARibosome
    • BGenome
    • CNucleoid
    • DCapsid
    Show answer & explanation

    Correct answer: D — Capsid

    The protein shell surrounding the nucleic acid in a virus particle is known as the capsid.

  2. Q2. Viroids are infectious agents that are structurally different from viruses primarily because they lack which component?

    • AProtein coat (Capsid)
    • BNucleic acid
    • CLipids
    • DRibonucleic acid
    Show answer & explanation

    Correct answer: A — Protein coat (Capsid)

    Viroids are infectious agents consisting only of a small, circular, single-stranded RNA molecule, lacking the protein coat (capsid) that is characteristic of viruses.

  3. Q3. The process by which a virus hijacks a host cell's machinery to produce new viral particles is known as:

    • ATransformation
    • BTranscription
    • CLysis
    • DReplication
    Show answer & explanation

    Correct answer: D — Replication

    Replication refers to the entire process where the viral genome is copied and new viral components are assembled using the host cell's resources.

  4. Q4. What is the fundamental structural component of a virus that protects its genetic material

    • ANucleoid
    • BCapsid
    • CCapsule
    • DRibosome
    Show answer & explanation

    Correct answer: B — Capsid

    The capsid is the protein shell that surrounds and protects the nucleic acid (genetic material) of the virus.

  5. Q5. Which type of genetic material is found in the nucleic acid core of most known viruses?

    • ARNA only
    • BBoth DNA and RNA
    • CDouble-stranded DNA only
    • DSingle-stranded RNA only
    Show answer & explanation

    Correct answer: A — RNA only

    Viruses exhibit diverse genetic material; they can possess either double-stranded DNA or single-stranded RNA, depending on the virus type.

  6. Q6. In the lytic cycle of a virus infection, what is the immediate consequence for the host cell?

    • AThe host cell enters a dormant state.
    • BThe virus integrates its genome into the host chromosome.
    • CThe host cell is lysed (bursts).
    • DThe host cell enters a lysogenic phase.
    Show answer & explanation

    Correct answer: C — The host cell is lysed (bursts).

    The lytic cycle culminates in the destruction (lysis) of the host cell to release the newly formed viral particles.

  7. Q7. The process by which a virus takes over a host cell to replicate its genetic material is known as

    • ABinary fission
    • BRespiration
    • CLytic cycle
    • DTransformation
    Show answer & explanation

    Correct answer: C — Lytic cycle

    The lytic cycle is the life cycle stage where the virus actively replicates inside the host cell, often leading to the host cell's destruction.

  8. Q8. Which of the following statements correctly describes the structural composition of a viroid?

    • AIt consists of a double-stranded DNA molecule and a protein capsid.
    • BIt is a complex virus requiring host cell machinery for replication.
    • CIt is a self-replicating entity that requires a host cell to produce proteins.
    • DIt is an infectious agent composed only of nucleic acid (RNA) without a protein coat.
    Show answer & explanation

    Correct answer: D — It is an infectious agent composed only of nucleic acid (RNA) without a protein coat.

    Viroids are infectious agents consisting only of a circular, single-stranded RNA molecule, lacking a protein coat (capsid). This distinguishes them from viruses, which possess a protein coat and DNA or RNA genome.

  9. Q9. Which of the following statements accurately describes a viroid

    • AViroids are infectious agents that require a host cell for replication.
    • BViroids are obligate parasites that always cause disease.
    • CViroids are complex viruses with a protein capsid.
    • DViroids are infectious agents consisting only of a naked RNA molecule.
    Show answer & explanation

    Correct answer: D — Viroids are infectious agents consisting only of a naked RNA molecule.

    Viroids are infectious agents defined solely by their RNA structure, lacking the protein coat found in viruses.

  10. Q10. Viruses are classified based on the nature of their genetic material. Which type of virus possesses a double-stranded DNA genome

    • AProtein virus
    • BDNA virus
    • CViroid
    • DRNA virus
    Show answer & explanation

    Correct answer: B — DNA virus

    DNA viruses (like Herpes or Adenovirus) possess a double-stranded DNA genome, while RNA viruses possess RNA genomes.

  11. Q11. The genetic material of a virus is typically composed of which type of nucleic acid?

    • ASingle-stranded RNA
    • BDouble-stranded RNA
    • CProtein
    • DDouble-stranded DNA
    Show answer & explanation

    Correct answer: A — Single-stranded RNA

    While some viruses use DNA, the majority of known viral genomes are RNA, which is characteristic of many smaller infectious agents like viroids and many viruses.

  12. Q12. Viroids differ fundamentally from viruses primarily because viroids lack which component found in viruses?

    • AReplication machinery
    • BHost cell recognition proteins
    • CRNA genome
    • DProtein capsid
    Show answer & explanation

    Correct answer: D — Protein capsid

    Viroids are infectious agents consisting only of a single-stranded RNA molecule (or similar nucleic acid) lacking a protein coat (capsid), distinguishing them from viruses.

  13. Q13. Which entity is considered a non-infectious infectious agent that causes diseases in plants by causing deletions in their RNA sequences?

    • ABacterium
    • BPrion
    • CVirus
    • DViroid
    Show answer & explanation

    Correct answer: D — Viroid

    Viroids are infectious agents consisting only of RNA, causing diseases in plants by altering host RNA sequences, without the need for a protein capsid.

  14. Q14. Which of the following is an infectious agent that consists only of a short, circular, single-stranded RNA molecule without any protein coat

    • AViroid
    • BVirus
    • CBacterium
    • DPrion
    Show answer & explanation

    Correct answer: A — Viroid

    Viroids are infectious agents consisting only of a circular RNA molecule, lacking a protein coat (unlike viruses).

  15. Q15. The structure that surrounds the nucleic acid (genome) of a virus and protects it is called the:

    • ACapsid
    • BNucleoid
    • CEnvelope
    • DCapsule
    Show answer & explanation

    Correct answer: A — Capsid

    The capsid is the protein shell or coat that encloses the viral genetic material (genome), providing structural protection.

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