1) Which of the following terms describes the protein shell that surrounds the viral genome?
a) capsid
b) envelope
c) matrix
d) virion
e) capsomere
Answer: a
2) Which of the following would not be a nucleic acid form found in a viral genome?
a) dsDNA
b) ssDNA
c) dsRNA
d) ssRNA
e) an RNA:DNA hybrid
Answer: e
3) Which of the following is an enzyme that most RNA viruses encode in their genome?
a) DNA-dependent-RNA-polymerase
b) RNA-dependent-RNA-polymerase
c) DNA-dependent-DNA-polymerase
d) DNA-dependent-RNA-polymerase
e) RNA-dependent-protein-synthetase
Answer: b
4) Viruses play a major role in the ecology of the ocean by doing which of the following?
a) By infecting photosynthetic bacteria and increasing their growth.
b) By infecting harmful bacteria found in the ocean and limiting their growth.
c) By killing off fish and preventing them from becoming too plentiful.
d) By lysing unicellular organisms and releasing carbon and oxygen back into the ocean.
e) All of the above statements are correct.
,Answer: d
5) If you wanted to show that an infectious agent is a virus, what experiment could you do?
a) Show that the agent can be seen under a light microscope.
b) Show that agent contains a lipid membrane.
c) Show that the agent can form single colonies on an agar plate.
d) Show that the agent can be diluted and can still cause disease in an animal.
e) Show that the agent can pass through a porcelain filter and is still infectious.
Answer: e
6) What does the word “virus” mean in Latin?
a) infectious agent
b) liquid
c) poison
d) death
e) disease
Answer: c
7) The word “phage” is a shortened version of the name of a virus that can infect which type of
organism?
a) bacterial cell
b) human cell
c) eukaryotic cell
d) plant cell
e) inset cell
Answer: a
8) The study of which group of viruses led to the discovery of cellular genes that can promoter
cancer in animal cells?
a) papillomaviruses
b) retroviruses
c) adneoviruses
d) polyomaviruses
e) picornaviruses
Answer: b
,9) When doing a plaque assay with human or animal cells, a layer of nutrient media mixed with
agar is put on top of the cells after they have been infected with the diluted virus. What is the
major purpose of this agar layer?
a) It helps to feed the cells as they grow.
b) It promotes the replication of the virus.
c) It makes the infected cells easier to visualize.
d) It limits the movement of virus particles.
e) All of the above are correct.
Answer: d
10) To start an experiment, you do an infection by putting 0.5 ml of a virus stock that has a titer
of 6 x 107 pfu/ml onto a plate of animal cells that contains 5 x 106 cells. What is the multiplicity
of infection for this experiment?
a) 12
b) 6
c) 5
d) 3
e) 1
Answer: b
11) During a single growth cycle experiment, the titer of extracellular and intracellular virus
drops in the first hour. What explains this observation?
a) The virus is inactivated by antibodies in the medium.
b) The virus is inactivated by cellular enzymes.
c) The virus enters the cell and is uncoated.
d) The virus binds to the cells in the dish and can’t be released.
e) The cell’s antiviral defenses prevent replication of the virus
Answer: c
12) What is another term for an RNA-dependent-DNA-polymerase?
a) DNA polymerase
b) RNA polymerase II
c) RNA replicase
d) RNA transcriptase
e) Reverse transcriptase
, Answer: e
13) Plant viruses use which cellular structures to spread between host cells?
a) endosomes
b) plasmodesmata
c) plasma membranes
d) vesicles
e) receptors
Answer: b
14) All viruses that use a negative-sense RNA genome must package which of the following
proteins in their virion?
a) RNA-dependent-RNA-polymerase
b) matrix protein
c) RNA helicase
d) RNA methylase
e) scaffolding protein
Answer: a
15) Which of the following is a description of a plaque?
a) A viral particle as seen by electron microscopy.
b) A region of dead cells in a monolayer of infected cells.
c) A skin lesion caused by a virus infection in an animal.
d) A button of red blood cells seen in a hemagglutination assay.
e) A region of crystallized virus particles in an infected cell.
Answer: b
16) Which of the following processes in cells was NOT discovered by studying a virus?
a) the sequence of the genetic code.
b) DNA replication in both prokaryotic and eukaryotic cells
c) DNA is the genetic material
d) regulation of gene expression in eukaryotic cells.
e) mRNA splicing in eukaryotic cells
Answer: a
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