1
.
Viruses were first discovered after the development of the porcelain filter, called the Chamberland-Pasteur filter. How did the porcelain filter enable scientists to discover viruses?
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The porcelain filter removed diseases from a liquid sample.
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The porcelain filter removed virions from a liquid sample.
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The porcelain filter removed bacteria from a liquid sample.
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The porcelain filter removed a disease from tobacco plants.
2
.
In the late 1930s, scientists got their first good view of viruses. How did this happen?
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The development of the light microscope helped scientists discover many viruses of all types of living organisms.
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The development of the viral receptor helped scientists discover many viruses of all types of living organisms.
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The development of the porcelain filter helped scientists discover many viruses of all types of living organisms.
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The development of the electron microscope helped scientists discover many viruses of all types of living organisms.
3
.
Determining the origins of viruses is challenging. The _____ hypothesis proposes to explain the origin of viruses by suggesting that viruses evolved from free-living cells.
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escapist or the progressive
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system of self-replication
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devolution or the regressive
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virus molecular systematics
4
.
Which statement best describes what biologists know about the evolution of viruses?
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Scientists can look at fossil records and similar historic evidence.
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Much about virus origins and evolution remains unknown.
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Biologists have accumulated a significant amount of knowledge about how viruses originated.
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Biologists know exactly when viruses emerged and from where they came.
5
.
A(n) _____ is an individual virus particle outside a host cell that consists of a nucleic acid core, an outer protein coating, and sometimes an outer envelope.
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A capsid
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A virion
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A capsomere
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A viral receptor
6
.
For many viruses to penetrate the cell membrane and complete their replication inside the cell, the virus must attach to their host cells. Describe how a virus attaches to a host cell.
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A virus uses its cellular structure to attach to a host cell.
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A virus uses a plasma membrane to connect to a host cell.
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A virus uses matrix proteins to attach to a host cell.
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Viruses use viral receptors to attach to a host cell.
7
.
_____ means that the genomic RNA can function as mRNA.
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Double-stranded
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Negative polarity
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Positive polarity
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Replica intermediates
8
.
Viruses are often classified based on the type of genetic material and its structure. In the Baltimore classification scheme, the _____ virus has a single-stranded RNA (–) genome.
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human immunodeficiency virus (HIV)
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rabies (rhabdovirus)
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canine parvovirus (parvovirus)
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common cold (pircornavirus)
9
.
Refer to Figure 21.4
.
To get a visual look at the internal structure of virions, scientists must use a ____.
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scanning electron microscope
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transmission electron microscope
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porcelain filter
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light microscope
10
.
Which of the following statements about the viral replication cycle is accurate?
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The viral replication cycle does not affect the structure of the host cell.
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The viral replication cycle cannot affect genetic material of the host cell.
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The viral replication cycle has seven basic steps.
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The viral replication cycle can change cell functions or even destroy the host cell.
11
.
What happens in the replication cycle?
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During the budding process, virions leave the host cell individually.
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During the budding process, the host cell bursts.
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During the budding process, the virus connects with a permissive host cell.
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During the budding process, the host cell dies immediately.
12
.
In the _____ cycle, the virus replicates and bursts out of the host cell.
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lytic
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lysogenic
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cytopathic
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latency
13
.
How is the lytic cycle different from the lysogenic cycle?
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The phage infects a cell in the lytic cycle.
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The lytic cycle contains the formation of a prophage.
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In the lytic cycle, new phages are produced; in the lysogenic cycle, phage DNA is merged into the host genome immediately.
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The phages move on to infect other cells in the lysogenic phase.
14
.
Which of the following statements is false?
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Enveloped viruses and naked viruses both may enter cells using the fusion method.
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Many enveloped viruses enter the cell by receptor-mediated endocytosis.
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Naked viruses enter the cell by receptor-mediated endocytosis.
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Undergoing shape changes and creating channels in the host cell membrane is an alternative method of cell penetration used by naked viruses.
15
.
An apple tree has yellow splotches on the leaves. This is a symptom of _____.
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cell necrosis
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discoloration
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hyperplasia
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hypoplasia
16
.
What happens during the release step in the viral replication cycle?
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During the release step, genetic information is transferred through the lytic and lysogenic cycles.
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During the release step, DNA is transcribed to messenger RNA.
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During the release step, the nucleic acid is released from the viral capsid or envelope.
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During the release step, the new virions are able to infect adjacent cells and repeat the replication cycle.
17
.
Why does the HIV virus use reverse transcriptase in the replication process?
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The HIV virus uses reverse transcriptase to replicate cells and build proteins.
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The HIV virus uses reverse transcriptase to erase mutated virions.
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The HIV virus uses reverse transcriptase because it is a retrovirus.
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The HIV virus uses reverse transcriptase because it has a DNA genome.
18
.
What are the symptoms of the herpes simplex virus?
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The herpes simplex virus causes skin lesions.
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The herpes simplex virus causes pneumonia.
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The herpes simplex virus causes pancreatitis.
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The herpes simplex virus can cause septicemia.
19
.
Which of the following statements accurately describes the measles virus?
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The measles virus causes nasal and lung infections.
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The measles virus causes pancreas and liver infections.
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The measles virus causes mouth and gum infections.
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The measles virus causes brain and skin infections.
20
.
Which of the following statements best describes vaccines?
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Vaccines kill viruses.
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Vaccines stimulate an immune response against future infections.
-
Vaccines inhibit the virus by blocking the action of key viral proteins.
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Vaccines control and reduce symptoms.
21
.
Which kind of therapy attacks a stage of the virus replicative cycle?
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phage therapy
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anti-retroviral
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gene therapy
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cancer therapy
22
.
Which virus causes parotitis?
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measles virus
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norovirus
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HIV
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mumps virus
23
.
Which of the following statements about prions is true?
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Prions are larger than viruses.
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Prions contain DNA and RNA.
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The PrPSC is the normal form of the protein.
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The PrPSC is folded abnormally.
24
.
Kuru is a prion disease that affects both humans and animals. How is Kuru spread?
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Kuru disease is spread between cattle.
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Kuru is passed from person to person.
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Kuru is passed from cows with BSE to humans.
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Kuru is a viroid that infects plants.
25
.
Which of the following statements about viroids is true?
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Viroids are single-stranded RNA particles.
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Viroids reproduce only outside of the cell.
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Viroids produce proteins.
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Viroids affect both plants and animals.
26
.
On which industry can viroids have a severe impact?
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dairy
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poultry
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avocado
-
livestock
27
.
Which of the following statements best explains how infected prions cause disease?
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Infected prions cause disease by transmitting nucleic acids to normal prion proteins.
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Infected prions cause disease by converting DNA to RNA in normal prion proteins.
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Infected prions cause disease by converting the shapes of normal proteins.
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Infected prions cause disease by replicating the normal form of the protein.