Free Viruses MCQs with Answers
247 Viruses MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Viruses are acellular infectious particles made of genetic material enclosed by a protein capsid, sometimes with a lipid envelope. Their replication depends on a host cell and may follow lytic or lysogenic cycles, so viral structure and reproduction differ fundamentally from those of cellular organisms such as bacteria.
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- A. Serum
- B. Faeco-oral
- C. Sexual contact
- D. All of these
Explanation: Hepatitis A virus is mainly transmitted by the faeco-oral route, when contaminated food or water carries the virus from faeces into…
Correct answer: Faeco-oral- A. Surrounded by genome
- B. Surrounding genome
- C. Surrounding the envelope
- D. Both B and C
Explanation: The capsid is the protein shell that encloses and protects the viral genome.
Correct answer: Surrounding genome- A. HAV
- B. HBV
- C. HCV
- D. HEV
Explanation: No routinely available preventive vaccine exists for hepatitis C because HCV has extensive genetic variation and changes its surface…
Correct answer: HCV- A. Virus
- B. Viral protein
- C. Viral lysozyme
- D. Viral gene
Explanation: A virion is a complete, mature virus particle outside a host cell, consisting of viral nucleic acid enclosed by a capsid and sometimes an…
Correct answer: Virus- A. We can not grow them in laboratories on artificial medias
- B. They are obligate intracellular parasite.
- C. They can synthesize their nucleic acid
- D. They are resistant to most of antibiotic treatment
Explanation: Viruses do not independently synthesize their nucleic acids because they lack the complete metabolic and protein-synthesis machinery of…
Correct answer: They can synthesize their nucleic acid- A. 100
- B. 152
- C. 162
- D. 172Preparing For College Admissions Tests
Explanation: The herpesvirus capsid is an icosahedral structure made of 162 capsomeres.
Correct answer: 162- A. Charles Chamberland
- B. Ivanowski
- C. Twort
- D. D Herelle
Explanation: Felix d'Herelle coined the term bacteriophage for viruses that infect and destroy bacteria.
Correct answer: D Herelle- A. Louis Pasteur
- B. Edward Jennar
- C. Ivanowski
- D. Stanely
Explanation: Edward Jenner developed the first successful vaccine by using material from cowpox lesions to protect against smallpox.
Correct answer: Edward Jennar- A. 10 - 100 times
- B. 10 - 1000 times
- C. 100 - 1000 times
- D. 1000 - 10000 times
Explanation: Viruses commonly measure about 20 to 300 nm, whereas bacteria are roughly 0.5 to 5 micrometres, or 500 to 5000 nm.
Correct answer: 10 - 1000 times- A. 10 nm
- B. 20 nm
- C. 30 nm
- D. 40 nm
Explanation: The smallest commonly cited viruses, such as parvoviruses, are approximately 20 nm in diameter.
Correct answer: 20 nm- A. Sweet fluid
- B. Sore Fluid
- C. Poisonous Fluid
- D. Salty Fluid
Explanation: The word virus comes from the Latin word meaning poison or poisonous fluid, reflecting the early view that viruses were harmful agents in…
Correct answer: Poisonous Fluid- A. Protein
- B. Carbohydrate
- C. Lipid
- D. DNA
Explanation: A virus's genetic material is enclosed in a protein coat called the capsid.
Correct answer: Protein- A. Lytic cycle
- B. Lysogenic cycle
- C. Both a & b
- D. All of these
Explanation: During the lytic cycle, viral genes direct the host cell to synthesize viral nucleic acid and capsid proteins, assemble new virions and…
Correct answer: Lytic cycle- A. RNA non-enveloped
- B. RNA enveloped
- C. DNA non-enveloped
- D. DNA enveloped
Explanation: Poxviruses are large double-stranded DNA viruses surrounded by a complex envelope derived from host membranes.
Correct answer: DNA enveloped- A. All RNA viruses
- B. All DNA viruses
- C. All retroviruses
- D. All viruses
Explanation: Retroviruses contain reverse transcriptase, which copies their RNA genome into DNA so it can integrate into the host-cell genome.
Correct answer: All retroviruses- A. They can be crystallized
- B. They occur in plants and animals
- C. They are microscopic
- D. They contain DNA and can be reproduced
Explanation: Viruses contain genetic material, either DNA or RNA, and can make new virus particles inside a suitable living host cell.
Correct answer: They contain DNA and can be reproduced- A. Athlete's foot
- B. Herpes simplex
- C. Mad cow disease
- D. Mumps and Measles
Explanation: Prions are misfolded proteins that can cause neurodegenerative diseases. They are infectious particles solely composed of proteins.
Correct answer: Mad cow disease- A. I only
- B. III only.
- C. I and II
- D. II and III
Explanation: Induction is the process where the prophage is activated and excises itself from the host chromosome, initiating the lytic cycle.
Correct answer: III only.- A. Prions
- B. Viroid
- C. Retrovirus
- D. Bacteriophage
Explanation: Creutzfeldt-Jakob disease (CJD) in humans is caused by prions, which are infectious proteins.
Correct answer: Prions- A. Synthesise viral genome
- B. Dissolve bacterial cell wall
- C. Break down bacterial DNA
- D. Speed up the formation of proteins
Explanation: In the lytic cycle, the correct function of lysozymes is to dissolve the bacterial cell wall, which allows the newly formed phage…
Correct answer: Dissolve bacterial cell wall