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. Landing → Tail contraction → Penetration → DNA Injection
- B. Penetration → Landing → Tail contraction → DNA Injection
- C. Tail contraction → Landing → DNA Injection → Penetration
- D. Landing → Penetration → Tail contraction → DNA Injection
Explanation: The phage first attaches itself by its tail to the cell wall of bacterium at a point called receptor site.
Correct answer: Landing → Tail contraction → Penetration → DNA Injection- A. Ectoparasites
- B. Endoparasites
- C. Obligative Intracellular Parasites
- D. Facultative Intracellular Parasites
Explanation: Intracellular obligate parasites depend on the host not only for nutrition but also for reproduction.
Correct answer: Obligative Intracellular Parasites- A. Mycoplasma
- B. Escherichia coli
- C. Herpes virus
- D. Diplococcus
Explanation: Herpes virus is essentially a virus and since viruses do not fall under the category of cellular beings, herpes virus is a non-cellular…
Correct answer: Herpes virus- A. Without invading any cell.
- B. In bacterial cell.
- C. By Mitosis
- D. By Meiosis
Explanation: Viruses are incapable of reproducing on their own, so they hunt for a host cell for hijacking.
Correct answer: In bacterial cell.- A. Transduction
- B. Temperate phage cycle
- C. Lytic cycle
- D. Lysogenic phage cycle
Explanation: In the lytic cycle the phage infects a bacterium, hijacks the bacterium to make lots of phages, and then kills the cell by making it…
Correct answer: Lytic cycle- A. Nucleocapsid
- B. Prion
- C. Envelope
- D. Capsomeres
Explanation: The capsid and nucleic acid together are known as the nucleocapsid.A prion is a type of protein that can trigger normal proteins in the…
Correct answer: Nucleocapsid- A. Enveloped Phage
- B. Virulent Phage
- C. Temperate phages
- D. Bacteriophage
Explanation: Temperate phages are some bacteriophages which display a lysogenic life cycle.
Correct answer: Temperate phages- A. Capsid
- B. Cosmid
- C. Capsomere
- D. Chromophore
Explanation: The outer protein coat of a virus is known as 'the capsid'. It consists of several oligomeric structural subunits made of a protein called…
Correct answer: Capsid- A. Cholera
- B. Tuberculosis
- C. Typhoid
- D. Poliomyelitis
Explanation: Option A: cholera is caused by a bacterium called Vibrio cholera (hence incorrect).
Correct answer: Poliomyelitis- A. HAV
- B. HBV
- C. HCV
- D. HIV
Explanation: The correct answer is HBV. HBV, also known as Hepatitis B Virus, has a single circular double-stranded DNA genome.
Correct answer: HBV- A. Abundant bacteria are present
- B. Abundant water is present
- C. Abundant nutrients are present
- D. They can only live at human body temperature
Explanation: Phages can translocate through the mucosa to lymph and internal organs and play a role as regulators of the bacterial population in the…
Correct answer: Abundant bacteria are present- A. Polyhedral shape
- B. Bad shape
- C. Tadpole shape
- D. Golf ball shape
Explanation: The polio virus has a polyhedral shape, which means it is roughly spherical with many flat sides or faces.
Correct answer: Polyhedral shape- A. Typhoid and plague
- B. Polio and measles
- C. Cholera and rabies
- D. Mumps and influenza
Explanation: Live attenuated vaccines are designed to provoke a strong immune response by using a weakened form of the virus.
Correct answer: Cholera and rabies- A. tetanus
- B. small pox
- C. tuberculosis
- D. diptheria
Explanation: Smallpox is caused by a virus, the variola virus, not a bacterium. Tetanus is caused by a bacterium called Clostridium tetani.
Correct answer: small pox- A. Head region
- B. Tail region
- C. Neck region
- D. Capsule region
Explanation: The phage virus uses its tail region to secrete lysozyme, an enzyme essential for breaking down the bacterial cell wall during the…
Correct answer: Tail region- A. Penicillin
- B. Histamine
- C. Interferon
- D. Antigens
Explanation: Interferons are a group of signaling proteins made and released by host cells in response to the presence of viruses.
Correct answer: Interferon- A. 50%
- B. 60%
- C. 80%
- D. 90%
Explanation: Polio, or poliomyelitis, is a disabling and potentially deadly disease. It is caused by the poliovirus.
Correct answer: 90%- A. 2-6 weeks
- B. 4-10 weeks
- C. 4-20 weeks
- D. 4-26 weeks
Explanation: Hepatitis C is a viral infection that affects the liver. It causes inflammation and swelling, which damages the liver tissues over time.
Correct answer: 4-20 weeks- A. Hepatitis A
- B. Hepatitis B
- C. Hepatitis C
- D. Hepatitis D
Explanation: Viroids are infectious agents that consist only of naked RNA without any protective layer such as a protein coat.
Correct answer: Hepatitis D- A. 1 - 2 weeks
- B. 2 - 3 weeks
- C. 3 - 4 weeks
- D. 4 - 5 weeks
Explanation: The correct answer is 2 - 3 weeks. Leaf curl disease symptoms in cotton typically become visible within this timeframe due to the…
Correct answer: 2 - 3 weeks