book questions

Question 1

1. Some viruses are characterized by helical symmetry of the viral nucleocapsid. Which of the following statements about viruses with helical symmetry is most accurate?
   (A) All enveloped viruses with helical symmetry are classified
   into the same virus family.
   (B) Helical nucleocapsids are found primarily in DNA-containing viruses.
   (C) All human viruses with helical nucleocapsids possess an envelope.
   (D) Excess empty helical particles containing no nucleic acid
   are commonly produced in infected cells.

Answer 1

(C) All human viruses with helical nucleocapsids possess an envelope

Question 2

2. 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?
   (A) They are pathognomonic for an infecting virus.
   (B) They are rarely associated with cell death.
   (C) They may include giant cell formation.
   (D) They can only be seen with an electron microscope.

Answer 2

(C) They may include giant cell formation.

Question 3

3. 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?
   (A) Cellular receptors for viruses have no known cellular function.
   (B) All viruses within a given family use the same cellular receptor
   (C) All cells in a susceptible host express the viral receptor.
   (D) Successful infection of a cell by a virus may involve interaction with more than one type of receptor.

Answer 3

(D) Successful infection of a cell by a virus may involve interaction with more than one type of receptor.

Question 4

4. Which of the following can be used to quantitate the titer of
   infectious viruses?
   (A) Plaque assay
   (B) Electron microscopy
   (C) Hemagglutination
   (D) Polymerase chain reaction
   (E) Enzyme immunoassay

Question 5

5. Which one of the following states a principle regarding viral nucleic acid?
   (A) Viruses contain both RNA and DNA.
   (B) Some viruses contain a segmented genome.
   (C) Purified viral nucleic acid from any virus is usually infectious.
   (D) Viral genome sizes are similar among known human viruses

Question 6

6. Two mutants of poliovirus have been isolated, one (MutX) with
   a mutation in gene X and the second (MutY) with a mutation
   in gene Y. If cells are infected with each mutant alone, no virus
   is produced. If a cell is coinfected with both MutX and MutY,
   which one of the following is most likely to occur?
   (A) Reassortment of genome segments may occur and give rise to a viable wild-type virus.
   (B) The genomes may be reverse transcribed to DNA and both MutX and MutY viruses produced.
   (C) Complementation between the mutant gene products may occur and both MutX and MutY viruses produced.
   (D) The cells will transform at high frequency because they will not be killed by the poliovirus mutants.