Medical Virology
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Questions and Answers

What is the bioscience that studies viral nature and the relationship between viruses and hosts?

  • Parasitology
  • Virology (correct)
  • Immunology
  • Bacteriology

    • When did the concept of virulation originate, according to the text?

  • 1000 yrs. BC in China (correct)
  • 5th century in Africa
  • 18th century in Europe
  • 20th century in America

    • What type of parasites are viruses considered to be?

  • Endoparasites
  • Ectoparasites
  • Extracellular parasites
  • Obligate intracellular parasites (correct)

    • Which century saw the discovery of bacteriophages, viruses that attack bacteria?

    <p>19th century</p> Signup and view all the answers

    What types of genome can viruses have based on the text?

    <p>Both RNA and DNA simultaneously</p> Signup and view all the answers

    Which of the following statements about viruses is true?

    <p>Viruses do not move or grow.</p> Signup and view all the answers

    What is a characteristic feature of viruses in terms of reproduction?

    <p>Viruses rely on host cell processes for replication.</p> Signup and view all the answers

    How are viruses different from bacteria in terms of size?

    <p>Bacteria are generally smaller than the largest viruses.</p> Signup and view all the answers

    Which of the following is essential for viruses to survive in nature?

    <p>Infectious nature</p> Signup and view all the answers

    What method can be used to measure the sizes of viruses?

    <p>Electron microscopy</p> Signup and view all the answers

    Who discovered transposons in 1950?

    <p>Barbara McClintock</p> Signup and view all the answers

    Which hypothesis proposes that viruses may have evolved from complex molecules at the same time as cells first appeared on Earth?

    <p>Coevolution hypothesis</p> Signup and view all the answers

    What do viroids interact with in host cells for their replication?

    <p>Host machinery</p> Signup and view all the answers

    Why did the escape hypothesis not explain the complex capsids and other structures on virus particles?

    <p>It required host cells for the virus origin</p> Signup and view all the answers

    What has led modern virologists to reconsider and re-evaluate classical hypotheses about viruses?

    <p>Discovery of ancient viruses</p> Signup and view all the answers

    According to the regressive hypothesis, what is the proposed origin of viruses?

    <p>Viruses may have once been small cells that parasitized larger cells.</p> Signup and view all the answers

    What lends support to the regressive hypothesis of virus origin?

    <p>Rickettsia and Chlamydia</p> Signup and view all the answers

    Which shape is associated with Filoviridae and Rhabdoviridae viruses?

    <p>Bullet-shaped</p> Signup and view all the answers

    What is the cellular origin hypothesis of viruses?

    <p>Bits of DNA or RNA escaped from larger organisms.</p> Signup and view all the answers

    Which type of viruses are suggested to have originated from plasmids or transposons?

    <p>Poxviruses</p> Signup and view all the answers

    What is the bioscience focused on studying viral nature and the relationship between viruses and hosts?

    <p>Virology</p> Signup and view all the answers

    When did virology originate?

    <p>1000 yrs. BC in China</p> Signup and view all the answers

    Which of the following best describes viruses as mentioned in the text?

    <p>Inert filterable agents requiring a host cell for energy and protein synthesis</p> Signup and view all the answers

    What type of parasites are viruses classified as in microbiology?

    <p>Obligate intracellular parasites</p> Signup and view all the answers

    Which century witnessed the discovery of bacteriophages, viruses that attack bacteria?

    <p>19th century</p> Signup and view all the answers

    What is a key characteristic of viruses in terms of their ability to multiply?

    <p>Viruses rely on host cell processes for multiplication</p> Signup and view all the answers

    Which statement accurately describes the relationship between viruses and unicellular organisms according to the text?

    <p>Viruses are known to infect a wide range of unicellular organisms</p> Signup and view all the answers

    How do viruses differ from bacteria in terms of growth and reproduction?

    <p>Viruses reproduce but do not grow</p> Signup and view all the answers

    Why can some bacteria be smaller than the largest viruses according to the text?

    <p>Bacteria can pass through filters that hold back viruses</p> Signup and view all the answers

    What is a method commonly used for analyzing the sizes of viruses according to the text?

    <p>Electron microscopy</p> Signup and view all the answers

    What is the alternative name for the vagrancy hypothesis regarding virus origins?

    <p>Escape Hypothesis</p> Signup and view all the answers

    Why is the regressive hypothesis not considered a valid explanation for the origin of viruses?

    <p>It does not explain the complex capsids of viruses</p> Signup and view all the answers

    Which hypothesis suggests that viruses evolved concurrently with the appearance of cells on Earth, depending on cellular life for billions of years?

    <p>Virus-First Hypothesis</p> Signup and view all the answers

    In what way do viroids differ from viruses?

    <p>Viroids interact with the host cell for replication</p> Signup and view all the answers

    Why does the virus-first hypothesis contradict the definition of viruses according to the text?

    <p>It assumes viruses do not require host cells</p> Signup and view all the answers

    What does the regressive hypothesis suggest about the origin of viruses?

    <p>Viruses originated from small cells that parasitized larger cells and lost unnecessary genes over time.</p> Signup and view all the answers

    Why do rickettsia and chlamydia lend support to the regressive hypothesis of virus origin?

    <p>Their dependence on parasitism likely led to gene loss similar to viruses.</p> Signup and view all the answers

    According to the cellular origin hypothesis, where could the escaped DNA that gave rise to some viruses have come from?

    <p>Transposons or plasmids</p> Signup and view all the answers

    What is a key difference between bacteria like rickettsia and chlamydia and viruses according to the text?

    <p>Bacteria can survive both inside and outside host cells, while viruses can only reproduce inside host cells.</p> Signup and view all the answers

    Which statement accurately describes the shape of Filoviridae and Rhabdoviridae viruses?

    <p>Bullet-shaped</p> Signup and view all the answers

    What is the alternative name for the escape hypothesis in virus origins?

    <p>Vagrancy hypothesis</p> Signup and view all the answers

    Why did the regressive hypothesis fail to provide a valid explanation for the origin of viruses?

    <p>It could not explain why even the smallest cellular parasites do not resemble viruses.</p> Signup and view all the answers

    What was a major limitation of the virus-first hypothesis regarding virus origins?

    <p>It contradicted the definition of viruses by requiring host cells.</p> Signup and view all the answers

    Why did the escape hypothesis not align with the presence of complex capsids and other structures on virus particles?

    <p>It overlooked the role of transposons in virus origins.</p> Signup and view all the answers

    Which term is used to describe viroids' dependency on host machinery for replication?

    <p>Satellites virus</p> Signup and view all the answers

    How do viroids differ from viruses in terms of protein coding?

    <p>Viroids lack protein-coding genes, unlike viruses.</p> Signup and view all the answers

    According to modern virologists, what has led to a re-evaluation of classical hypotheses about viruses?

    <p>The recognition of viruses as ancient entities</p> Signup and view all the answers

    Why was the regressive hypothesis unable to explain why even the smallest cellular parasites do not resemble viruses?

    <p>It did not address the absence of complex capsids on virus particles.</p> Signup and view all the answers

    What historical significance do transposons hold in the context of virology?

    <p>They are considered a form of ancient viruses.</p> Signup and view all the answers

    What sets viroids apart from traditional viral particles in terms of their interaction with host cells?

    <p>Viroids utilize host machinery for replication without coding proteins.</p> Signup and view all the answers

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