Virus Structure Practice Questions
18 free Virus Structure practice questions for the Microbiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What is the basic structure of a virus?
- A Cell membrane and nucleus
- B Cytoplasm with metabolic enzymes
- C Cell wall and organelles
- D DNA or RNA with protein coat
Correct answer: DNA or RNA with protein coat
Viruses consist of genetic material (DNA or RNA) surrounded by a protein coat called a capsid. They lack cellular structures.
What is the protein coat of a virus called?
- A Envelope
- B Nucleoid
- C Capsid
- D Matrix
Correct answer: Capsid
The capsid is the protein shell that protects viral genetic material. It is made of repeating protein subunits.
What are capsomeres?
- A Enzymes used in viral replication
- B Genetic material
- C Protein subunits of capsid
- D Lipid molecules
Correct answer: Protein subunits of capsid
Capsomeres are the individual protein units that make up the capsid. They assemble to form the viral coat.
What type of genetic material can viruses contain?
- A DNA molecules only
- B RNA molecules only
- C Both DNA and RNA
- D Either DNA or RNA
Correct answer: Either DNA or RNA
Viruses contain either DNA or RNA as their genetic material, but never both. This distinguishes them from cellular organisms.
What is the viral envelope?
- A Protein coat
- B Genetic material
- C Outer lipid layer
- D Capsomere structure
Correct answer: Outer lipid layer
The viral envelope is a lipid membrane derived from the host cell. It surrounds some viruses and contains glycoproteins.
Which viruses lack an envelope?
- A Non-enveloped viruses
- B Enveloped viruses
- C Segmented RNA viruses
- D DNA viruses only
Correct answer: Non-enveloped viruses
Non-enveloped viruses have only a capsid surrounding their genetic material. They are often more resistant to environmental conditions.
What is the function of viral spikes?
- A Attach to host cells
- B Protect the viral DNA
- C Produce energy
- D Replicate RNA
Correct answer: Attach to host cells
Viral spikes are glycoproteins on the surface that help viruses bind to host cell receptors. They are essential for infection.
Which of the following is NOT a standard morphological category of viruses?
- A Icosahedral
- B Helical
- C Cuboidal
- D Complex
Correct answer: Cuboidal
Cuboidal is not a recognized viral morphology. Viruses are typically classified into three main shape categories: icosahedral (roughly spherical), helical (rod-shaped), and complex (such as bacteriophages with head-and-tail structures).
Which virus has a complex structure with head and tail?
- A Bacteriophage
- B Influenza virus
- C HIV
- D Adenovirus
Correct answer: Bacteriophage
Bacteriophages have a complex structure with a head, tail, and tail fibers. They infect bacterial cells.
What is the function of the viral genome?
- A Encode viral proteins
- B Provide metabolic energy
- C Protect host cell
- D Form capsid
Correct answer: Encode viral proteins
The viral genome contains genetic information needed to produce viral proteins and replicate the virus inside host cells.
Which part of the virus interacts with host cell receptors?
- A Envelope proteins or spikes
- B Capsid only
- C The nucleic acid core
- D The tail fibers and baseplate
Correct answer: Envelope proteins or spikes
Envelope proteins or spikes recognize and bind to host cell receptors. This determines host specificity.
Which virus type contains reverse transcriptase enzyme?
- A DNA viruses
- B RNA viruses
- C Retroviruses
- D Bacteriophages
Correct answer: Retroviruses
Retroviruses carry reverse transcriptase, which converts RNA into DNA. This allows integration into the host genome.
Which viral component is derived from the host cell membrane?
- A Capsid
- B Envelope
- C Genome
- D Capsomere
Correct answer: Envelope
The viral envelope is derived from the host cell membrane during viral budding. It contains host and viral proteins.
Which structure helps bacteriophages attach to bacteria?
- A Capsid
- B Tail fibers
- C Envelope
- D Spike proteins
Correct answer: Tail fibers
Tail fibers of bacteriophages recognize and bind to bacterial cell surfaces. This initiates infection.
Which virus shape resembles a rod?
- A Icosahedral
- B Helical
- C Complex
- D Spherical
Correct answer: Helical
Helical viruses have a rod-like shape with capsomeres arranged in a spiral. Tobacco mosaic virus is a classic example.
Which viruses are more sensitive to drying and detergents?
- A Non-enveloped viruses
- B Enveloped viruses
- C DNA viruses
- D Bacteriophages
Correct answer: Enveloped viruses
Enveloped viruses are sensitive to drying and detergents because their lipid envelope can be easily disrupted.
Which viral structure determines host specificity?
- A Capsid protein
- B Genome composition
- C Surface proteins
- D Tail length
Correct answer: Surface proteins
Surface proteins or spikes determine which host cells a virus can infect. They bind to specific receptors on host cells.
Which type of capsid symmetry is common in many viruses?
- A Icosahedral
- B Cylindrical
- C Circular
- D Triangular
Correct answer: Icosahedral
Icosahedral symmetry is common in many viruses and provides structural stability. It consists of 20 triangular faces.