Deck 13: Viruses, Viroids, and Prions

Question 1

A viroid is

A) A naked, infectious piece of RNA.
B) A complete, infectious virus particle.
C) A provirus.
D) A capsid without a nucleic acid.
E) None of the above.

Answer 1

A

Question 2

Bacteriophages derive all of the following from the host cell except

A) tRNA.
B) Nucleotides.
C) Lysozyme.
D) Amino acids.
E) None of the above.

Answer 2

C

Question 3

Continuous cell lines differ from primary cell lines in that

A) Continuous cell lines are derived from primary cell lines.
B) Viruses can be grown in continuous cell lines.
C) Continuous cell lines are from human embryos.
D) Continuous cell lines always have to be reisolated from animal tissues.
E) Continuous cell lines can be maintained through an indefinite number of generations.

Answer 3

E

Question 4

The definition of lysogeny is

A) Lysis of the host cell due to a phage.
B) Phage DNA is incorporated into host cell DNA.
C) When the burst time takes an unusually long time.
D) The period during replication when virions are not present.
E) None of the above.

Question 5

The following steps occur during multiplication of Herpesviruses. What is the third step?

A) Biosynthesis
B) Uncoating
C) Release
D) Attachment
E) Penetration

Question 6

Most RNA viruses carry which of the following enzymes?

A) Lysozyme
B) DNA- dependent DNA polymerase
C) ATP synthase
D) Reverse transcriptase
E) RNA- dependent RNA polymerase

Question 7

Latent viruses are present in cells as

A) Enzymes.
B) Capsids.
C) Proviruses.
D) Prophages.
E) None of the above.

Question 8

Which of the following statements is not true?

A) Prophage genes are represented by a repressor protein coded for by the prophage.
B) A prophage is phage DNA inserted into a bacterial chromosome.
C) A prophage may result in new properties of the host cell.
D) The prophage makes the host cell immune to infection by other phages.
E) A prophage can pop out of the chromosome.

Question 9

To which group does a small, nonenveloped single- stranded RNA virus most likely belong?

A) Herpesvirus
B) Togavirus
C) Picornavirus
D) Retrovirus
E) None of the above

Question 10

An envelope is acquired during which of the following steps?

A) Release
B) Penetration
C) Uncoating
D) Adsorption
E) None of the above

Question 11

Generalized transduction differs from specialized transduction in that generalized transduction

A) Transfers specific DNA.
B) Involves lysogeny.
C) Kills the host.
D) Transfers DNA from one cell to another.
E) None of the above.

Question 12

A clear area against a confluent "lawn" of bacteria is called a

A) Plaque.
B) Phage.
C) Cell lysis.
D) Pock.
E) None of the above.

Question 13

The most conclusive evidence that viruses cause cancers is provided by

A) Finding oncogenes in viruses.
B) Treating cancer with antibodies.
C) Some liver cancer patients having had hepatitis.
D) Cancer following injection of cell- free filtrates.
E) The presence of antibodies against viruses in cancer patients.

Question 14

Put the following in the correct order for DNA- virus replication:
1- Maturation; 2- DNA synthesis; 3- Transcription; 4- Translation.

A) 4, 1, 2, 3
B) 2, 3, 4, 1
C) 3, 4, 1, 2
D) 1, 2, 3, 4
E) 4, 3, 2, 1

Question 15

Which of the following contributes to the difficulty in establishing the etiology of cancer?

A) Cancers do not seem to be contagious.
B) Viruses are difficult to observe.
C) Most viral particles can infect cells without inducing cancer.
D) Cancer may not develop until long after infection.
E) All of the above.

Question 16

Assume you have isolated an unknown virus. It is a single- stranded RNA, enveloped virus. To which group does it most likely belong?

A) Herpesvirus
B) Picornavirus
C) Togavirus
D) Retrovirus
E) None of the above

Question 17

A persistent infection is an infection in which

A) The disease process occurs gradually over a long period.
B) Host cells are transformed.
C) The virus remains in equilibrium with the host without causing a disease.
D) Host cells are gradually lysed.
E) Viral replication is unusually slow.

Question 18

Approximately how many virus particles could fit along a 1 millimeter line?

A) 20,000
B) 2,000,000
C) 2
D) 20
E) 200

Question 19

Which of the following is necessary for replication of a prion?

A) PSc
B) RNA
C) DNA polymerase
D) DNA
E) Lysozyme

Question 20

Viruses that have reverse transcriptase are in the

A) Bacteriophage families.
B) Influenzavirus.
C) Retroviridae and Picornaviridae.
D) Herpesviridae and Retroviridae.
E) Hepadnaviridae and Retroviridae.

Question 21

An infectious protein is a

A) Retrovirus
B) Prion
C) Viroid
D) Bacteriophage
E) None of the above

Question 22

Which of the following provides the most significant support for the idea that viruses are nonliving chemicals?

A) They cannot reproduce themselves outside of a host.
B) They are filterable.
C) They are chemically simple.
D) They are not composed of cells.
E) They cause diseases similar to those caused by chemicals.

Question 23

Lysogeny can result in all of the following except

A) Transduction of specific genes.
B) Immunity to reinfection by the same phage.
C) Immunity to reinfection by any phage.
D) Acquisition of new characteristics by the host cell.
E) None of the above.

Question 24

An example of a latent viral infection is

A) Cold sores.
B) Subacute sclerosing panencephalitis.
C) Influenza.
D) Smallpox.
E) None of the above.

Question 25

Which of the following would be the first step in biosynthesis of a virus with a - strand of RNA?

A) Synthesis of double- stranded RNA from an RNA template
B) Transcription of mRNA from DNA
C) Synthesis of DNA from an RNA template
D) Synthesis of double- stranded RNA from a DNA template
E) None of the above

Question 26

The following steps occur during multiplication of Retroviruses. What is the fourth step?

A) Attachment
B) Penetration
C) Synthesis of + RNA
D) Uncoating
E) Synthesis of double- stranded DNA

Question 27

Which of the following is not a method of culturing viruses?

A) In embryonated eggs
B) In laboratory animals
C) In cell culture
D) In culture media
E) None of the above

Question 28

Generally, in a DNA- containing virus infection, the host animal cell supplies all of the following
Except

A) RNA polymerase.
B) tRNA.
C) DNA polymerase.
D) Nucleotides.
E) None of the above.

Question 29

Bacteriophages and animal viruses do not differ significantly in which one of the following steps?

A) Adsorption
B) Penetration
C) Biosynthesis
D) Release
E) Uncoating

Question 30

In which of the following ways do viruses differ from bacteria?

A) Viruses are filterable.
B) Viruses are obligate intracellular parasites.
C) Viruses are not composed of cells.
D) Viruses don't have any nucleic acid.
E) All of the above.

Question 31

The most common route of accidental AIDS transmission to health- care workers is

A) Environmental surface contact.
B) Mouth to mouth.
C) Fecal- oral.
D) Aerosol.
E) Needlestick.

Question 32

Which one of the following steps does not occur during multiplication of a Picornavirus?

A) Synthesis of viral proteins
B) Synthesis of - strands of RNA
C) Synthesis of + strands of RNA
D) Synthesis of DNA
E) None of the above

Question 33

Which of the following is not used as a criterion to classify viruses?

A) Size
B) Number of capsomeres
C) Morphology
D) Nucleic acid
E) Biochemical tests

Question 34

The following steps occur during biosynthesis of a + strand RNA virus. What is the third step?

A) Synthesis of - strand RNA
B) Synthesis of viral proteins
C) Penetration and uncoating
D) Attachment
E) Synthesis of + strand RNA

Question 35

Which of the following is most likely a product of an early gene?

A) Capsid proteins
B) Envelope proteins
C) Spike proteins
D) Lysozyme
E) DNA polymerase

Question 36

DNA made from an RNA template will be incorporated into the virus capsid of

A) Influenzavirus.
B) Retroviridae.
C) Bacteriophage families.
D) Hepadnaviridae.
E) Herpesviridae.

Question 37

Figure 13.1

In Figure 13.1, the structures illustrated are composed of

A) RNA
B) DNA
C) Capsomeres
D) Capsids
E) DNA or RNA

Question 38

Some viruses, such as Human Herpes Virus 1, infect a cell without causing symptoms; these are called

A) Slow viruses.
B) Lytic viruses.
C) Phages.
D) Latent viruses.
E) Unconventional viruses.

Question 39

Which one of the following steps does not occur during multiplication of a Rhabdovirus?

A) Synthesis of DNA
B) Synthesis of viral proteins
C) Synthesis of - strands of RNA
D) Synthesis of + strands of RNA

Question 40

Figure 13.1

In Figure 13.1, which of these is a complex virus?

A) a
B) b
C) c
D) d
E) All of the above

Question 41

A viral species is a group of viruses that

A) Have the same genetic information and ecological niche.
B) Have the same morphology and nucleic acid.
C) Infect the same cells and cause the same disease.
D) Can't be defined.

Question 42

Which of the following is not true about viruses?

A) Viruses contain DNA or RNA but never both.
B) Viruses use the anabolic machinery of the cell.
C) Viruses contain a protein coat.
D) Viruses use their own catabolic enzymes.
E) None of the above.

Question 43

An oncogenic RNA virus must have which of the following enzymes?

A) Lysozyme
B) Reverse transcriptase
C) RNA polymerase
D) DNA- dependent DNA polymerase
E) All of the above

Question 44

Nontoxic strains of Vibrio cholerae can become toxic when they are in the human intestine with toxic strains of bacteria. This suggests that the toxin genes are acquired by

A) Prions.
B) Reverse transcriptase.
C) Host enzymes.
D) Transduction.
E) None of the above.

Question 45

Which of the following is not true about spikes?

A) They may cause hemagglutination.
B) They are only found on enveloped viruses.
C) They are used for penetration.
D) They are used for absorption.
E) None of the above.