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Chapter 29: General Properties of Viruses
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Some viruses are characterized by helical symmetry of the viral nucleocapsid. Which of the following statements about viruses with helical symmetry is most accurate?
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(A) All enveloped viruses with helical symmetry are classified into the same virus family.
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(B) Helical nucleocapsids are found primarily in DNA-containing viruses.
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(C) All human viruses with helical nucleocapsids possess an envelope.
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(D) Excess empty helical particles containing no nucleic acid are commonly produced in infected cells.
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Virus-infected cells often develop morphologic changes referred to as cytopathic effects. Which of the following statements about virus-induced cytopathic changes is most accurate?
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(A) They are pathognomonic for an infecting virus.
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(B) They are rarely associated with cell death.
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(C) They may include giant cell formation.
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(D) They can only be seen with an electron microscope.
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Viruses usually initiate infection by first interacting with receptors on the surface of cells. Which of the following statements is most accurate about cellular receptors for viruses?
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(A) Cellular receptors for viruses have no known cellular function.
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(B) All viruses within a given family use the same cellular receptor.
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(C) All cells in a susceptible host express the viral receptor.
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(D) Successful infection of a cell by a virus may involve interaction with more than one type of receptor.
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Which of the following can be used to quantitate the titer of infectious viruses?
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(D) Polymerase chain reaction
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Which one of the following states a principle regarding viral nucleic acid?
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(A) Viruses contain both RNA and DNA.
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(B) Some viruses contain a segmented genome.
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(C) Purified viral nucleic acid from any virus is usually infectious.
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(D) Viral genome sizes are similar among known human viruses.
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Two mutants of poliovirus have been isolated, one (MutX) with a mutation ...