Microbio Ch 13

A clear area against a confluent "lawn" of bacteria is called a A) rash. B) phage. C) pock. D) cell lysis. E) plaque.

E

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

E

Bacteriophages derive all of the following from the host cell EXCEPT A) nucleotides. B) tRNA. C) ATP. D) amino acids. E) lysozyme.

E

What contributes to antigenic shift in influenza viruses? A) different virus subtypes B) attachment spikes C) worldwide distribution of the virus D) ease of virus transmission E) a segmented genome

E

Which of the following statements is FALSE? A) A prophage may result in new properties of the host cell. 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 is phage DNA inserted into a bacterial chromosome. E) The prophage makes the host cell immune to infection by other phages.

E

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

True

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

True

An example of a latent viral infection is A) cold sores. B) influenza. C) mumps. D) smallpox. E) subacute sclerosing panencephalitis.

A

An infectious protein is a A) prion. B) bacteriophage. C) papovavirus. D) viroid. E) retrovirus.

A

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) papovavirus D) picornavirus E) retrovirus

A

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage? A) The cell could still be revived by the virus. B) The virus would not be able to infect new hosts. C) The virus would infect new hosts.

B

Which of the following events might trigger induction of a temperate bacteriophage? A) Normal cell division of an infected cell B) Exposure to UV light C) An infected cell entering the logarithmic phase of growth D) Bacterial conjugation

B

Which of the following is true of viroids? A) There are similarities between the base sequences of viroids and exons, resulting in the hypothesis that viroids evolved from exons. B) Viroids are short pieces of naked RNA. C) Viroid is the term for a virus that infects plants. D) Viroids are typically extremely long and contain numerous genes.

B

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) transcription of mRNA from DNA E) synthesis of DNA from an RNA template

B

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? A) The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA. B) The phage lyses the bacterium and releases resistance genes into the local environment, which can then be taken up by recipient cells. C) The phage causes the destruction of any antibiotic present during the specialized transduction process.

A

How do all viruses differ from bacteria? A) Viruses are not composed of cells. B) Viruses are filterable. C) Viruses are obligate intracellular parasites. D) Viruses do not reproduce. E) Viruses do not have any nucleic acid.

A

Lysogenic viral DNA integrating into the host genome is referred to as A) a prophage. B) induction. C) lytic. D) lysogeny.

A

The structures illustrated in the figure are composed of A) Capsomeres. B) RNA. C) viroids. D) DNA. E) DNA or RNA.

A

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 are chemically simple. E) They cause diseases similar to those caused by chemicals.

A

How does specialized transduction differ from regular lysogeny? A) The resulting bacteriophage from specialized transduction cannot infect a new host cell. B) The prophage in specialized transduction carries with it pieces of the host chromosomal DNA. C) The resulting bacteriophage from specialized transduction does not contain any viral DNA. D) The prophage is not excised during specialized transduction.

B

In which stage is the viral DNA introduced into the cell? A) Attachment B) Penetration C) Release D) Assembly E) Biosynthesis

B

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? A) The DNA is chewed up by enzymes found in the recipient cell. B) The host DNA integrates, with the prophage, into the new recipient chromosome. C) The DNA begins to replicate without integrating into the host chromosome.

B

What is the fate of the prophage during the lysogenic stage? A) It is released from the cell by lysing the cell. B) It is copied every time the host DNA replicates. C) It is degraded by the activity of host defense enzymes. D) It is packaged into viral proteins and maintained until the host is exposed to an environmental stress.

B

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

C

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves A) assembly of viral components. B) lysis of the host cell. C) injection of naked nucleic acid into the host cell. D) replication of viral nucleic acid. E) adsorption to specific receptors.

C

Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps? A) release B) attachment C) biosynthesis D) uncoating E) penetration

C

Generally, in an infection caused by a DNA-containing virus, the host animal cell supplies all of the following EXCEPT A) tRNA. B) RNA polymerase. C) DNA polymerase. D) nucleotides. E) None of the answers are correct; all of these are supplied by the host animal cell.

C

How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell? A) The viral DNA may integrate into the host genome during the lytic stage. B) The host cell is allowed to live during the lytic stage. C) The host cell dies during the lytic stage. D) The host cell can only divide during the lytic stage.

C

In which stage does formation of mature viruses occur? A) Release B) Attachment C) Assembly D) Penetration E) Biosynthesis

C

Lysogeny can result in all of the following EXCEPT A) acquisition of new characteristics by the host cell. B) immunity to reinfection by the same phage. C) immunity to reinfection by any phage. D) specialized transduction. E) phage conversion.

C

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

C

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

C

What is the function of the structural elements of a virus? A) To provide a source of energy for the virus B) To use all of the cell proteins C) To package and protect the viral genome

C

Which of the following is NOT used as a criterion to classify viruses? A) morphology B) number of capsomeres C) biochemical tests D) size E) nucleic acid

C

Which of the following is true concerning a lysogenic viral replication cycle? A) During lysogeny, the viral DNA is present as a circular plasmid. B) Once the lysogenic portion of the cycle has begun, virus is never produced again. C) During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome. D) Lysogenic infections are similar to persistent infections in that virus is constantly produced.

C

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

C

Which of the following statements about viral spikes is FALSE? A) They are used for attachment. B) They bind to receptors on the host cell surface. C) They are found only on nonenveloped viruses. D) They are composed of carbohydrate-protein complexes. E) They may cause hemagglutination.

C

Which statement concerning viral structure is true? A) All viruses contain an envelope, which is made of lipid, carbohydrate, and protein. B) The proteins in the envelope are capsomeres. C) Spikes are found on some viruses. They are very consistent in structure and can be used for identification. D) Animal viruses usually contain tail sheaths and spikes.

C

An envelope is acquired during which of the following steps? A) biosynthesis B) uncoating C) adsorption D) release E) penetration

D

How are viruses different from cells? A) They do not contain protein. B) They do not contain genetic material. C) They do not contain enzymes. D) They require a host in order to reproduce.

D

Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called A) lytic viruses. B) unconventional viruses. C) phages. D) latent viruses. E) slow viruses.

D

The host DNA is usually degraded during which stage? A) Assembly B) Penetration C) Release D) Biosynthesis E) Attachment

D

The mechanism whereby an enveloped virus leaves a host cell is called A) abduction. B) lysogeny. C) penetration. D) budding. E) transduction.

D

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.

D

Which of the following statements concerning viruses is true? A) Viruses are usually about the same size as bacteria. B) Viruses contain both DNA and RNA, and they undergo binary fusion. C) Viruses possess enzymes for protein synthesis and ATP generation. D) The "host range" for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach.

D

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

D

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

False

Glycoprotein spikes are found on the capsids of all viruses. True False

False

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

False

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

False