Deck 13: Viruses, Viroids, and Prions

Question 1

An example of a latent viral infection is

A) cold sores.
B) subacute sclerosing panencephalitis.
C) influenza.
D) smallpox.
E) mumps.

Answer 1

A

Question 2

A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient?

A) The virus is infecting cells and then releasing only small amounts of virus.
B) The virus is not killing any cells in the host.
C) The virus is causing the death of the infected cells in the patient.
D) The virus is incorporating its nucleic acid with that of the patient's cells.
E) The virus is slowly killing the patient's cells.

Answer 2

C

Question 3

Generally, in an infection caused by a DNA- containing virus, the host animal cell supplies all of the following EXCEPT

A) tRNA.
B) nucleotides.
C) RNA polymerase.
D) DNA polymerase.
E) None of the answers are correct; all of these are supplied by the host animal cell.

Answer 3

D

Question 4

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

A) uncoating
B) attachment
C) release
D) penetration
E) biosynthesis

Question 5

Oncogenic viruses
B) cause acute infections.
C) have no effect on the host cell.
D) are lytic viruses that kill the host cell.
E) cause tumors to develop.

Question 6

Which of the following is NOT utilized to culture viruses?

A) animal cell cultures
B) embryonated eggs
C) culture media
D) laboratory animals
E) bacterial cultures

Question 7

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

A) Herpesviridae.
B) Retroviridae.
C) Hepadnaviridae.
D) influenzavirus.
E) bacteriophage families.

Question 8

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves

A) injection of naked nucleic acid into the host cell.
B) replication of viral nucleic acid.
C) adsorption to specific receptors.
D) lysis of the host cell.
E) assembly of viral components.

Question 9

Bacteriophages derive all of the following from the host cell EXCEPT

A) lysozyme.
B) ATP.
C) tRNA.
D) amino acids.
E) nucleotides.

Question 10

The definition of lysogeny is

A) the period during replication when virions are not present.
B) phage DNA is incorporated into host cell DNA.
C) attachment of a phage to a cell.
D) lysis of the host cell due to a phage.
E) when the burst time takes an unusually long time.

Question 11

A persistent infection is one in which

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

Question 12

Which of the following places these items in the correct order for DNA- virus replication? 1. Maturation
2) DNA synthesis
3) Transcription
4) Translation

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

Question 13

Viruses that utilize reverse transcriptase belong to the virus families

A) Herpesviridae and Poxviridae.
B) Rhabdoviridae and Herpesviridae.
C) Retroviridae and Picornaviridae.
D) Hepadnaviridae and Retroviridae.
E) Herpesviridae and Retroviridae.

Question 14

How do all viruses differ from bacteria?

A) Viruses are not composed of cells.
B) Viruses do not have any nucleic acid.
C) Viruses are filterable.
D) Viruses do not reproduce.
E) Viruses are obligate intracellular parasites.

Question 15

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

A) penetration and uncoating
B) synthesis of - strand RNA
C) synthesis of viral proteins
D) attachment
E) synthesis of + strand RNA

Question 16

A viroid is a(n)

A) infectious protein.
B) provirus.
C) capsid without nucleic acid.
D) complete, infectious virus particle.
E) infectious piece of RNA without a capsid.

Question 17

Which of the following statements about viral spikes is FALSE?

A) They are composed of carbohydrate- protein complexes.
B) They bind to receptors on the host cell surface.
C) They are used for attachment.
D) They are found only on nonenveloped viruses.
E) They may cause hemagglutination.

Question 18

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

A) spike proteins
B) DNA polymerase
C) lysozyme
D) envelope proteins
E) capsid proteins

Question 19

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

A) synthesis of double- stranded RNA from a DNA template
B) synthesis of double- stranded RNA from an RNA template
C) synthesis of DNA from a DNA template
D) synthesis of DNA from an RNA template
E) transcription of mRNA from DNA

Question 20

The mechanism whereby an enveloped virus leaves a host cell is called

A) budding.
B) lysogeny.
C) penetration.
D) transduction.
E) abduction.

Question 21

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

A) morphology
B) nucleic acid
C) biochemical tests
D) size
E) number of capsomeres

Question 22

Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called

A) slow viruses.
B) lytic viruses.
C) unconventional viruses.
D) phages.
E) latent viruses.

Question 23

Figure 13.1

In Figure 13.1, which structure is a complex virus?

A) a
B) b
C) c
D) d
E) All of the structures are complex viruses.

Question 24

Most RNA viruses carry which of the following enzymes?

A) ATP synthase
B) DNA- dependent DNA polymerase
C) reverse transcriptase
D) RNA- dependent RNA polymerase
E) lysozyme

Question 25

Which of the following statements is FALSE?

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

Question 26

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

A) RNA
B) DNA
C) lysozyme
D) DNA polymerase
E) PrP^Sc

Question 27

A virus's ability to infect an animal cell depends primarily upon the

A) host cell's ability to phagocytize viral particles.
B) type of viral nucleic acid.
C) enzymatic activity of a host cell.
D) presence of receptor sites on the cell membrane.
E) presence of pili on the host cell wall.

Question 28

Figure 13.1

The structures illustrated in Figure 13.1 are composed of

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

Question 29

What contributes to antigenic shift in influenza viruses?

A) attachment spikes
B) different virus subtypes
C) a segmented genome
D) ease of virus transmission
E) worldwide distribution of the virus

Question 30

The following steps occur during multiplication of retroviruses. Which is the fourth step?

A) penetration
B) uncoating
C) synthesis of double- stranded DNA
D) attachment
E) synthesis of +RNA

Question 31

An envelope is acquired during which of the following steps?

A) penetration
B) release
C) uncoating
D) biosynthesis
E) adsorption

Question 32

Figure 13.2

Assume a patient has influenza. During which time on the graph in Figure 13.2 would the patient show the symptoms of the illness?

A) a
B) b
C) c
D) d
E) e

Question 33

Assume you have isolated an unknown virus. This virus has a single, positive sense strand of RNA, and possesses an envelope. To which group does it most likely belong?

A) togavirus
B) herpesvirus
C) picornavirus
D) papovavirus
E) retrovirus

Question 34

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

A) plaque.
B) phage.
C) rash.
D) pock.
E) cell lysis.

Question 35

Figure 13.2

Assume a patient had chickenpox (human herpesvirus 3) as a child. Which line on the graph in Figure 13.2 would show the number of viruses present in this person as a 60- year- old with shingles (human herpesvirus 3)?

A) a
B) b
C) c
D) d
E) e

Question 36

Lysogeny can result in all of the following EXCEPT

A) immunity to reinfection by the same phage.
B) immunity to reinfection by any phage.
C) acquisition of new characteristics by the host cell.
D) phage conversion.
E) specialized transduction.

Question 37

An infectious protein is a

A) prion.
B) papovavirus.
C) retrovirus.
D) bacteriophage.
E) viroid.

Question 38

Which of the following statments is NOT true of lysogeny?

A) Prophage is inserted into the host genome.
B) Lytic cycle may follow lysogeny.
C) It is a "silent" infection; the virus does not replicate.
D) It causes lysis of host cells.
E) It can give infected pathogens the genetic information for toxin production.

Question 39

A viral species is a group of viruses that

A) has the same genetic information and ecological niche.
B) has the same morphology and nucleic acid.
C) infects the same cells and cause the same disease.
D) cannot be defined.

Question 40

Continuous cell lines differ from primary cell lines in that

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

Question 41

Glycoprotein spikes are found on the capsids of all viruses.

Question 42

The following steps occur during multiplication of herpesviruses. Which is the third step?

A) penetration
B) attachment
C) release
D) uncoating
E) biosynthesis

Question 43

Viruses are the only known infectious agents that are obligatory intracellular parasites.

Question 44

Which one of the following steps does NOT occur during multiplication of a picornavirus?

A) synthesis of - strands of RNA
B) synthesis of + strands of RNA
C) synthesis of viral proteins
D) synthesis of DNA
E) None of the answers is correct.

Question 45

A viroid is a completely developed infectious agent composed of nucleic acid and surrounded by a capsid.

Question 46

A segmented genome can result in antigenic shift.

Question 47

Helical and icosahedral are terms used to describe the shapes of a virus envelope.

Question 48

Dogs do not get measles because their cells lack the correct receptor sites for that virus.

Question 49

The basic mechanism of viral multiplication is similar for all viruses.

Question 50

The most conclusive evidence that viruses cause cancers is provided by

A) cancer following injection of cell- free filtrates.
B) finding oncogenes in viruses.
C) some liver cancer patients having had hepatitis.
D) treating cancer with antibodies.
E) the presence of antibodies against viruses in cancer patients.

Question 51

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

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

Question 52

Binomial nomenclature is used to name viruses.

Question 53

Positive sense RNA strands of viruses are treated like mRNA inside the host cell.

Question 54

Which of the following statements about viruses is FALSE?

A) Viruses contain a protein coat.
B) Viruses contain DNA or RNA but never both.
C) Viruses have genes.
D) Viruses use their own catabolic enzymes.
E) Viruses use the anabolic machinery of the cell.

Question 55

Most drugs that interfere with viral multiplication also interfere with host cell function.