Micro exam 3 Flashcards

1) How do all viruses differ from bacteria?

A) Viruses are filterable.

B) Viruses are obligate intracellular parasites.

C) Viruses do not have any nucleic acid.

D) Viruses are not composed of cells.

E) Viruses do not reproduce.

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

A) They are not composed of cells.

B) They are filterable.

C) They cannot reproduce themselves outside a host.

D) They cause diseases similar to those caused by chemicals.

E) They are chemically simple.

Which of the following statements about viral spikes is FALSE?

A) They are composed of carbohydrate-protein complexes.

B) They are used for attachment.

C) They may cause hemagglutination.

D) They bind to receptors on the host cell surface.

E) They are found only on nonenveloped viruses.

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

A) Biochemical tests

B) morphology

C) nucleic acid

D) size

E) number of capsomeres

Which of the following is NOT utilized to culture viruses?

A) laboratory animals

B) culture media

C) embryonated eggs

D) animal cell cultures

E) bacterial cultures

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

A) attachment

B) penetration

C) uncoating

D) biosynthesis

E) release

The definition of lysogeny is

A) phage DNA is incorporated into host cell DNA.

B) lysis of the host cell due to a phage.

C) the period during replication when virions are not present.

D) when the burst time takes an unusually long time.

E) attachment of a phage to a cell.

A viroid is a(n)

A) complete, infectious virus particle.

B) infectious piece of RNA without a capsid.

C) capsid without nucleic acid.

D) provirus.

E) infectious protein.

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.

The structures illustrated in Figure 13.1 are composed of

A) DNA.

B) RNA.

C) DNA or RNA.

D) Capsomeres.

E) viroids.

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

A) phage.

B) pock.

C) cell lysis.

D) plaque.

E) rash.

Continuous cell lines differ from primary cell lines in that

A) viruses can be grown in continuous cell lines.

B) continuous cell lines always have to be re-isolated from animal tissues.

C) continuous cell lines are derived from primary cell lines.

D) continuous cell lines can be maintained through an indefinite number of generations.

E) continuous cell lines are from human embryos.

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

A) DNA

B) DNA polymerase

C) lysozyme

D) PrPSc

E) RNA

A persistent infection is one in which

A) the virus remains in equilibrium with the host without causing a disease.

B) viral replication is unusually slow.

C) the disease process occurs gradually over a long period.

D) host cells are gradually lysed.

E) host cells are transformed.

Which of the following statements is FALSE?

A) A prophage is phage DNA inserted into a bacterial chromosome.

B) A prophage can pop out of the chromosome.

C) Prophage genes are repressed by a repressor protein coded for by the prophage.

D) A prophage may result in new properties of the host cell.

E) The prophage makes the host cell immune to infection by other phages.

Lysogeny can result in all of the following EXCEPT

A) immunity to reinfection by the same phage.

B) acquisition of new characteristics by the host cell.

C) immunity to reinfection by any phage.

D) specialized transduction.

E) phage conversion.

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

A) synthesis of DNA from an RNA template

B) synthesis of double-stranded RNA from an RNA template

C) synthesis of double-stranded RNA from a DNA template

D) transcription of mRNA from DNA

E) synthesis of DNA from a DNA template

An infectious protein is a

A) bacteriophage.

B) prion.

C) retrovirus.

D) viroid.

E) papovavirus.

An envelope is acquired during which of the following steps?

A) penetration

B) adsorption

C) uncoating

D) biosynthesis

E) release

Which of the following statements is NOT true of lysogeny?

A) It can give infected pathogens the genetic information for toxin production.

B) Prophage is inserted into the host genome.

C) Lytic cycle may follow lysogeny.

D) It is a silent infection; the virus does not replicate.

E) It causes lysis of host cells.

An example of a latent viral infection is

A) subacute sclerosing panencephalitis.

B) cold sores.

C) influenza.

D) smallpox.

E) mumps.

A viruss ability to infect an animal cell depends primarily upon the

A) host cells ability to phagocytize viral particles.

B) presence of receptor sites on the cell membrane.

C) type of viral nucleic acid.

D) enzymatic activity of a host cell.

E) presence of pili on the host cell wall.

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) herpesvirus

B) picornavirus

C) retrovirus

D) togavirus

E) papovavirus

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

A) transduction.

B) budding.

C) abduction.

D) lysogeny.

E) penetration.

The most conclusive evidence that viruses cause cancers is provided by

A) finding oncogenes in viruses.

B) the presence of antibodies against viruses in cancer patients.

C) cancer following injection of cell-free filtrates.

D) treating cancer with antibodies.

E) some liver cancer patients having had hepatitis.

Bacteriophages derive all of the following from the host cell EXCEPT

A) lysozyme.

B) tRNA.

C) amino acids.

D) nucleotides.

E) ATP.

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

A) adsorption to specific receptors.

B) assembly of viral components.

C) replication of viral nucleic acid.

D) injection of naked nucleic acid into the host cell.

E) lysis of the host cell.

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

A) RNA polymerase.

B) nucleotides.

C) DNA polymerase.

D) tRNA.

E) None of the answers are correct; all of these are supplied by the host animal cell.

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) 2; 3; 4; 1

C) 3; 4; 1; 2

D) 4; 1; 2; 3

E) 4; 3; 2; 1

A viral species is a group of viruses that

A) has the same morphology and nucleic acid.

B) has the same genetic information and ecological niche.

C) infects the same cells and cause the same disease.

D) cannot be defined.

Viruses that utilize reverse transcriptase belong to the virus families

A) Retroviridae and Picornaviridae.

B) Herpesviridae and Retroviridae.

C) Hepadnaviridae and Retroviridae.

D) Herpesviridae and Poxviridae.

E) Rhabdoviridae and Herpesviridae.

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

A) Retroviridae.

B) Herpesviridae.

C) Hepadnaviridae.

D) bacteriophage families.

E) influenzavirus.

Which of the following statements about viruses is FALSE?

A) Viruses contain DNA or RNA but never both.

B) Viruses contain a protein coat.

C) Viruses use the anabolic machinery of the cell.

D) Viruses use their own catabolic enzymes.

E) Viruses have genes.

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

A) The virus is causing the death of the infected cells in the patient.

B) The virus is not killing any cells in the host.

C) The virus is incorporating its nucleic acid with that of the patients cells.

D) The virus is slowly killing the patients cells.

E) The virus is infecting cells and then releasing only small amounts of virus.

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

A) Latent viruses.

B) lytic viruses.

C) phages.

D) slow viruses.

E) unconventional viruses.

Figure 13.2

36) 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

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

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

A) attachment

B) biosynthesis

C) penetration

D) release

E) uncoating

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

A) synthesis of double-stranded DNA

B) synthesis of +RNA

C) attachment

D) penetration

E) uncoating

Oncogenic viruses

A) cause acute infections.

B) are genetically unstable.

C) cause tumors to develop.

D) are lytic viruses that kill the host cell.

E) have no effect on the host cell.

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.

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

A) capsid proteins

B) DNA polymerase

C) envelope proteins

D) spike proteins

E) lysozyme

Most RNA viruses carry which of the following enzymes?

A) DNA-dependent DNA polymerase

B) lysozyme

C) RNA-dependent RNA polymerase

D) reverse transcriptase

E) ATP synthase

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

A) attachment

B) penetration and uncoating

C) synthesis of strand RNA

D) synthesis of + strand RNA

E) synthesis of viral proteins

What contributes to antigenic shift in influenza viruses?

A) worldwide distribution of the virus

B) a segmented genome

C) attachment spikes

D) ease of virus transmission

E) different virus subtypes

________ were first identified in cancer-causing viruses and can induce ________ in infected cells.

A) Herpes viruses; lesions

B) Oncogenes; transformation

C) T antigens; lysis

D) Glycoprotein spikes; syncytia formation

E) Segmented genomes; reassortment

True/False Question

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

True/False Question

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

True/False Question

Binomial nomenclature is used to name viruses.

True/False Question

Glycoprotein spikes are found on the capsids of all viruses.

True/False Question

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

True/False Question

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

True/False Question

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

True/False Question

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

True/False Question

A segmented genome can result in antigenic shift.

True/False Question

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