BIOL 315 Exam 2 Study Guide with Questions
Answers
Chapter 6: Viruses
1) RNA retroviruses use
- viral reverse transcriptase to make a DNA copy that is integrated into the host
genome and then host RNA polymerase transcribes it.
2) Which of the following conditions may lead to a switch from a lysogenic to a lytic
life cycle?
- A dearth of glucose in the environment
3) Which viruses enter cells via mechanical transmission, a nonspecific access
through physical damage?
- Plant viruses
4) Reverse transcriptase catalyzes production from a template.
- DNA; RNA
5) Culturing viruses in tissue culture
- allows for testing of a variety of chemical and biological agents against the virus.
6) A prophage is a
- phage genome integrated into a host genome.
7) Viral genomes may comprise
- double or single-stranded DNA or double or single-stranded RNA.
8) Compared with the number of antibiotics, the number of antiviral drugs is
small because
- viruses use host cell machinery to replicate.
9) New and emerging viruses come from
- “jumping” hosts.
10) Viruses are capable of converting into a(n)
- virion, an intracellular replication complex, and an integrated part of the host genome.
11) Which of the following statements is true?
- Viruses may limit host population density.
12) The viral capsid is comprised of
- proteins.
13) CRISPR is
- a set of short DNA sequences that allow the bacterium to “remember” past infections.
, 14) RNAi
- recognizes viral mRNA and prevents further viral gene expression.
15) In the analogy of a computer virus to a biological virus, a personal computer
is analogous to
- a cell.
16) What is the correct ordering of the phases of growth in a virus?
Infection, eclipse, latent, rise
17) Compared with cells that are surrounded by a lipid membrane, viruses
- may be surrounded by a membrane derived from the host cell.
18) Virus phylogeny based on proteomics is
- possible because viruses encode a small number of proteins.
19) A temperate phage is one that
- can undergo lysogeny.
20) Which viruses may enter cells via receptor-mediated endocytosis?
- Animal viruses
21) The International Committee on the Taxonomy of Viruses uses the following
criteria to classify viruses EXCEPT
- mRNA type.
22) A gene for a is likely to be encoded in the viral genome.
, - capsid protein
23) Which of the following is true of prion diseases?
- They lead to neurodegeneration.
24) Culturing viruses in a laboratory is more complicated than culturing
bacteria because
- viruses must be cocultured with a host cell.
25) In the plaque assay for bacteriophages,
- the plaque is a clear zone caused by a zone of lysis.
26) Viruses infect
- all three domains of life.
27) Compared with cellular genomes, viral genomes
- are smaller, with fewer base pairs.
28) Viroids
lack
- proteins.
29) A virus cycle leads only to cell lysis, and a virus cycle involves phage
genome integration into the host genome.
- lytic; lysogenic
30) A specific virus always infects
- The number of species depends on the virus.
1. Correctly order the steps necessary to perform a plaque assay with phages.
Answers
Chapter 6: Viruses
1) RNA retroviruses use
- viral reverse transcriptase to make a DNA copy that is integrated into the host
genome and then host RNA polymerase transcribes it.
2) Which of the following conditions may lead to a switch from a lysogenic to a lytic
life cycle?
- A dearth of glucose in the environment
3) Which viruses enter cells via mechanical transmission, a nonspecific access
through physical damage?
- Plant viruses
4) Reverse transcriptase catalyzes production from a template.
- DNA; RNA
5) Culturing viruses in tissue culture
- allows for testing of a variety of chemical and biological agents against the virus.
6) A prophage is a
- phage genome integrated into a host genome.
7) Viral genomes may comprise
- double or single-stranded DNA or double or single-stranded RNA.
8) Compared with the number of antibiotics, the number of antiviral drugs is
small because
- viruses use host cell machinery to replicate.
9) New and emerging viruses come from
- “jumping” hosts.
10) Viruses are capable of converting into a(n)
- virion, an intracellular replication complex, and an integrated part of the host genome.
11) Which of the following statements is true?
- Viruses may limit host population density.
12) The viral capsid is comprised of
- proteins.
13) CRISPR is
- a set of short DNA sequences that allow the bacterium to “remember” past infections.
, 14) RNAi
- recognizes viral mRNA and prevents further viral gene expression.
15) In the analogy of a computer virus to a biological virus, a personal computer
is analogous to
- a cell.
16) What is the correct ordering of the phases of growth in a virus?
Infection, eclipse, latent, rise
17) Compared with cells that are surrounded by a lipid membrane, viruses
- may be surrounded by a membrane derived from the host cell.
18) Virus phylogeny based on proteomics is
- possible because viruses encode a small number of proteins.
19) A temperate phage is one that
- can undergo lysogeny.
20) Which viruses may enter cells via receptor-mediated endocytosis?
- Animal viruses
21) The International Committee on the Taxonomy of Viruses uses the following
criteria to classify viruses EXCEPT
- mRNA type.
22) A gene for a is likely to be encoded in the viral genome.
, - capsid protein
23) Which of the following is true of prion diseases?
- They lead to neurodegeneration.
24) Culturing viruses in a laboratory is more complicated than culturing
bacteria because
- viruses must be cocultured with a host cell.
25) In the plaque assay for bacteriophages,
- the plaque is a clear zone caused by a zone of lysis.
26) Viruses infect
- all three domains of life.
27) Compared with cellular genomes, viral genomes
- are smaller, with fewer base pairs.
28) Viroids
lack
- proteins.
29) A virus cycle leads only to cell lysis, and a virus cycle involves phage
genome integration into the host genome.
- lytic; lysogenic
30) A specific virus always infects
- The number of species depends on the virus.
1. Correctly order the steps necessary to perform a plaque assay with phages.
