How do all viruses differ from bacteria?
-Viruses are not composed of cells.
-Viruses are filterable.
-Viruses are obligate intracellular parasites.
-Viruses do not have any nucleic acid.
-Viruses do not reproduce.
Viruses are not composed of cells.
A feature that may be found in viruses but never in bacteria is
-an ability to infect more than one type of host.
-They cannot reproduce themselves outside a host.
-The ability to pass through 0.22 micrometer pore filters.
-May contain an RNA genome.
-A sensitivity to antibiotics.
May contain an RNA genome.
Which of the following is NOT used as a criterion to classify viruses?
-Biochemical tests
-Size
-Morphology
-Nucleic acid
-Number of capsomeres
Biochemical tests
Which of the following is NOT utilized to culture viruses?
-Embryonated eggs
-Animal cell cultures
-Laboratory animals
-Culture media
-Bacterial cultures
Culture media
Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?
-Release
-Uncoating
-Penetration
-Attachment
-Biosynthesis
Biosynthesis
The definition of lysogeny is
-when the burst time takes an unusually long time.
-Attachment of a phage to a cell.
-Phage DNA is incorporated into host cell DNA.
-Lysis of the host cell due to a phage.
-The period during replication when virions are not present.
Phage DNA is incorporated into host cell DNA.
A viroid is a(n)
-Infectious protein.
-Provirus.
-Capsid without nucleic acid.
-Complete, infectious virus particle.
-Infectious piece of RNA without a capsid.
Infectious piece of RNA without a capsid.
In Figure 13.1, which structure is a complex virus?
a
b
c
d
All of the structures are complex viruses.
b
The morphological types of viruses illustrated in Figure 13.1 are ultimately determined by the
-membrane spikes.
-Capsomeres.
-Viroids.
-Envelope.
-Nucleic acid.
Nucleic acid.
A clear area against a confluent "lawn" of bacteria is called a
-rash.
-Cell lysis.
-Plaque.
-Pock.
-Phage.
Plaque.
Continuous cell lines differ from primary cell lines in that
-continuous cell lines always have to be re-isolated from animal tissues.
-Viruses can be grown in continuous cell lines.
-Continuous cell lines can be maintained through an indefinite number of generations.
-Continuous cell lines are from human embryos.
-Continuous cell lines are derived from primary cell lines.
Continuous cell lines can be maintained through an indefinite number of generations.
Which of the following is necessary for replication of a prion?
-Lysozyme
-DNA polymerase
-DNA
-PrPSc
-RNA
PrPSc
A persistent infection is one in which
-host cells are transformed.
-Host cells are gradually lysed.
-The virus remains in equilibrium with the host without causing a disease.
-The disease process occurs gradually over a long period.
-Viral replication is unusually slow.
The disease process occurs gradually over a long period.
An example of a persistent viral infection is
-Varicellavirus infection.
-Influenza.
-Herpes Simplex Virus infection.
-Hepatitis A infection.
-Human Immunodeficiency Virus infection.
Varicellavirus infection.
Lysogeny can result in all of the following EXCEPT
-immunity to reinfection by the same phage.
-Immunity to reinfection by any phage.
-Acquisition of new characteristics by the host cell.
-Specialized transduction.
-Phage conversion.
Immunity to reinfection by any phage.
Which of the following would be the first step in biosynthesis of a virus with a - (minus) strand of RNA?
-Synthesis of double-stranded RNA from a DNA template
-Transcription of mRNA from DNA
-Synthesis of double-stranded RNA from an RNA template
-Synthesis of DNA from an RNA template
-Synthesis of DNA from a DNA template
Synthesis of double-stranded RNA from an RNA template
An infectious protein is a retrovirus.
-Viroid.
-Papovavirus.
-Prion.
-Bacteriophage.
Prion.
An envelope is acquired during which of the following steps?
-Biosynthesis
-Release
-Adsorption
-Penetration
-Uncoating
Release
Which of the following statements is NOT true of lysogeny?
-Lytic cycle may follow lysogeny.
-Prophage is inserted into the host genome.
-It causes lysis of host cells.
-It can give infected pathogens the genetic information for toxin production.
-It is a "silent" infection; the virus does not replicate.
It causes lysis of host cells.
An example of a latent viral infection is
-subacute sclerosing panencephalitis.
-Cold sores.
-Smallpox.
-Influenza.
-Mumps.
Cold sores.
A virus's ability to infect an animal cell depends primarily upon the
-host cell's ability to phagocytize viral particles.
-Enzymatic activity of a host cell.
-Type of viral nucleic acid.
-Presence of receptor sites on the cell membrane.
-Presence of pili on the host cell wall.
Presence of receptor sites on the cell membrane.
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?
-Herpesvirus
-Retrovirus
-Togavirus
-Picornavirus
-Papovavirus
Togavirus
The mechanism whereby an enveloped virus leaves a host cell is called
-abduction.
-Penetration.
-Lysogeny.
-Transduction.
-Budding.
Budding
The most conclusive evidence that viruses cause cancers was provided by
-the presence of antibodies against viruses in cancer patients.
-Finding oncogenes in viruses.
-Cancer that developed in chickens following injection of cell-free filtrates.
-Treating cancer with antibodies.
-Some liver cancer patients having had hepatitis.
Cancer that developed in chickens following injection of cell-free filtrates.
Bacteriophages derive all of the following from the host cell EXCEPT
-ATP.
-Amino acids.
-Nucleotides.
-Lysozyme.
-tRNA.
Lysozyme.
Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves
-replication of viral nucleic acid.
-Injection of naked nucleic acid into the host cell.
-Assembly of viral components.
-Lysis of the host cell.
-Adsorption to specific receptors.
Injection of naked nucleic acid into the host cell.
Generally, in an infection caused by a DNA-containing virus, the host animal cell supplies all of the following EXCEPT
-tRNA.
-RNA polymerase.
-Nucleotides.
-DNA polymerase.
-None of the answers are correct; all of these are supplied by the host animal cell.
DNA polymerase.
Which of the following places these items in the correct order for DNA-virus replication?
1. Maturation
2. DNA synthesis
3. Transcription
4. Translation
-1; 2; 3; 4
-3; 4; 1; 2
-4; 1; 2; 3
-2; 3; 4; 1
-4; 3; 2; 1
2; 3; 4; 1
A viral species is a group of viruses that
-has the same genetic information and ecological niche.
-Infects the same cells and causes the same disease.
-Has the same morphology and nucleic acid.
-Cannot be defined.
has the same genetic information and ecological niche.
Viruses that utilize reverse transcriptase belong to the virus families
-Retroviridae and Picornaviridae.
-Hepadnaviridae and Retroviridae.
-Rhabdoviridae and Herpesviridae.
-Herpesviridae and Retroviridae.
-Herpesviridae and Poxviridae.
Hepadnaviridae and Retroviridae.
DNA made from an RNA template will be incorporated into the virus capsid of
-influenzavirus.
-Retroviridae.
-Hepadnaviridae.
-Herpesviridae.
-Bacteriophage families.
Hepadnaviridae.
Which of the following statements about viruses is FALSE?
-Viruses use their own catabolic enzymes.
-Viruses use the anabolic machinery of the cell.
-Viruses contain a protein coat.
-Viruses contain DNA or RNA but never both.
-Viruses have genes.
Viruses use their own catabolic enzymes.
A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient?
-The virus is infecting cells and then releasing only small amounts of virus.
-The virus is incorporating its nucleic acid with that of the patient's cells.
-The virus is slowly killing the patient's cells.
-The virus is causing the death of the infected cells in the patient.
-The virus is not killing any cells in the host.
The virus is causing the death of the infected cells in the patient.
Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called
-lytic viruses.
-Slow viruses.
-Latent viruses.
-Unconventional viruses.
-Phages.
Latent viruses.
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
b
c
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
b
c
d
e
c
The following steps occur during multiplication of herpesviruses. Which is the third step?
-Biosynthesis
-Uncoating
-Release
-Attachment
-Penetration
Uncoating
The following steps occur during multiplication of retroviruses. Which is the fourth step?
-Uncoating
-Synthesis of double-stranded DNA
-Attachment
-Penetration
-Synthesis of +RNA
Synthesis of double-stranded DNA
Oncogenic viruses
-have no effect on the host cell.
-Cause acute infections.
-Are genetically unstable.
-Are lytic viruses that kill the host cell.
-Cause tumors to develop.
Cause tumors to develop.
Which one of the following steps does NOT occur during multiplication of a picornavirus?
-Synthesis of + strands of RNA
-Synthesis of - strands of RNA
-Synthesis of DNA
-Synthesis of viral proteins
-None of the answers is correct.
Synthesis of DNA
Which of the following is most likely a product of an early gene?
-Envelope proteins
-Spike proteins
-DNA polymerase
-Lysozyme
-Capsid proteins
DNA polymerase
Most RNA viruses carry which of the following enzymes?
-DNA-dependent DNA polymerase ATP synthase Lysozyme Reverse transcriptase RNA-dependent RNA polymerase
RNA-dependent RNA polymerase
What is NOT true regarding viruses that infect plants?
-They can sometimes be cultured in insect cells.
-They must enter through a wound or be introduced by an insect feeding.
-They can spread via pollination.
-They are morphologically similar to animal viruses.
-They are often cultured in embryonated chicken eggs.
They are often cultured in embryonated chicken eggs.
What contributes to antigenic shift in influenza viruses?
-Ease of virus transmission
-Different virus subtypes Attachment spikes
-A segmented genome
-Worldwide distribution of the virus
A segmented genome
________ were first identified in cancer-causing viruses and can induce ________ in infected cells.
-Segmented genomes; reassortment
-Oncogenes; transformation
-Herpes viruses; lesions
-Glycoprotein spikes; syncytia formation
-T antigens; lysis
Oncogenes; transformation
What is an oncogene?
-an altered form of a gene that may induce cancer
-a viral ligand found in a family of viruses
-a viral polymerase
-a problematic gene found exclusively in viruses
-a toxin gene transferred by a virus
an altered form of a gene that may induce cancer
Which of the following statements about viral spikes is FALSE?
-They may cause hemagglutination.
-They bind to receptors on the host cell surface.
-They are found only on nonenveloped viruses.
-They are used for attachment.
-They are composed of carbohydrate-protein complexes.
They are found only on nonenveloped viruses.
What is the key characteristic of a transformed cell?
-is
producing toxins affecting neighboring cells
-has undergone chromosomal rearrangements
-is infected with a lytic virus
-has acquired tumor-forming properties
-is producing budding viruses
has acquired tumor-forming properties
Shingles is an example of
-reactivation of latent virus.
-lytic virus.
-transformation.
-persistent virus.
-lysogeny.
reactivation of latent virus.
Why do most scientists agree that viruses are nonliving entities?
-They are not composed of cells.
-They cause diseases in host cells.
-They are composed of relatively simple components.
-They cannot replicate outside host cells.
-They pass through filters.
They are not composed of cells.