Deck 13: Characterizing and Classifying Viruses, Viroids, and Prions

Question 1

The genome of influenzavirus is

A) multiple pieces of linear dsDNA.
B) a single circular ssRNA.
C) a single linear dsRNA.
D) a single circular ssDNA.
E) multiple pieces of linear ssRNA.

Answer 1

E

Question 2

Which of the following lists stages of a lytic replication cycle in order, from earliest to latest stages?
I) Synthesis
II) Assembly
III) Attachment
IV) Release
V) Entry

A) III, V, I, II, IV
B) III, II, V, I, IV
C) V, III, II, IV, I
D) I, III, V, II, IV
E) I, II, III, V, IV

Answer 2

A

Question 3

How are fungal viruses transmitted?

A) by insect vectors
B) as a result of abrasion
C) as a result of fusion of cells or hyphae
D) in the air like spores
E) by contact

Answer 3

C

Question 4

Which of the following is primarily responsible for the shape of a virion?

A) the type of nucleic acid
B) the number of segments of the viral genome
C) the source of the envelope
D) the capsid
E) the specific host protein the virus targets

Question 5

Which of the following statements regarding virus taxonomy is true?

A) Viruses are classified on the basis of the taxonomy of their host organisms.
B) Virus classes are well established.
C) Some virus family names are derived from the name of an important member of the family.
D) The species epithet is a latin descriptor of the virion structure.
E) Virus classes are based on the domain of the host organism.

Question 6

Which of the following is associated with the attachment of a bacteriophage to a bacterial cell?

A) random collisions
B) chemical attractions
C) receptor specificity
D) both chemical attractions and receptor specificity
E) random collisions, chemical attractions, and receptor specificity

Question 7

A(n) ________ is a virus that infects bacterial cells.

A) virion
B) prion
C) bacteriophage
D) nucleocapsid
E) envelope

Question 8

Which of the following is a characteristic by which viruses are classified?

A) type of nucleic acid
B) type of life cycle
C) number of chromosomes
D) type of host
E) size

Question 9

Host specificity of a virus is due to

A) particular genes that it shares with the infected cell.
B) the presence of an envelope.
C) differences in size between the virus and the host cell.
D) the presence or absence of a cell wall on the host cell.
E) interactions between viral and cellular surface molecules.

Question 10

The outermost layer of a virion fulfills which of the following functions of the virus?

A) protection
B) recognition
C) replication
D) both protection and recognition
E) both recognition and replication

Question 11

A(n) ________ is a bacterial virus which is integrated into the host cell DNA.

A) lytic phage
B) prophage
C) plasmid
D) transposon
E) insertion phage

Question 12

The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle?

A) entry
B) assembly
C) entry and release
D) synthesis
E) attachment

Question 13

In what ways do viruses differ from other pathogens?

A) Viruses lack genetic material.
B) Viruses lack cytoplasm and organelles.
C) Viruses have no protein structure.
D) Viruses are composed of protein only.
E) Viruses are composed of both protein and lipid.

Question 14

Which of the following agents is capable of inducing conversion of a prophage to the lytic cycle?

A) UV light
B) X rays
C) presence of +ssRNA
D) both UV light and X rays
E) both UV light and the presence of +ssRNA

Question 15

Replication of most ________ viruses is similar to normal cellular processes.

A) dsDNA
B) ssDNA
C) +ssRNA
D) -ssRNA
E) dsRNA

Question 16

Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but not in the lysogenic cycle?

A) attachment
B) entry
C) digestion of host DNA
D) viral protein synthesis
E) both digestion of host DNA and viral proteins synthesis

Question 17

Why is lysogeny advantageous to a bacteriophage?

A) it speeds up the viral infection cycle.
B) the genetic material of the bacteriophage is amplified many times over that seen in a lytic phage.
C) it allows the bacteriophage to infect cells it would not normally infect.
D) it allows the bacteriophage to destroy the host cell's DNA.
E) it enables the bacteriophage to take over the cell.

Question 18

Which of the following is CORRECT regarding the viral envelope?

A) It contains only viral proteins.
B) It contains only host cell proteins.
C) It is composed of sterols.
D) It is composed of cellular phospholipid membrane, cellular and viral proteins.
E) It is composed of sterols of viral proteins only.

Question 19

Attachment of herpesviruses results in ________, a process in which the host cell facilitates viral entry.

A) direct penetration
B) membrane fusion
C) endocytosis
D) exocytosis
E) lysogeny

Question 20

Which of the following is NOT used for the classification of viruses?

A) genus
B) class
C) specific epithet
D) family
E) order

Question 21

Viroids infect

A) bacteria.
B) plants.
C) fungi.
D) plants and animals.
E) all organisms.

Question 22

Small circular RNAs called ________ are plant pathogens.

A) plasmids
B) viruses
C) viroids
D) prions
E) phages

Question 23

Which of the following infectious particles do not have protein in their structure?

A) bacteriophages
B) prions
C) animal viruses
D) viroids
E) both prions and viroids

Question 24

Tumors invade other organs and tissues in a process called

A) neoplasia.
B) uncoating.
C) latency.
D) budding.
E) metastasis.

Question 25

What is a virion?

A) a virus genome inside a cell
B) an empty capsid
C) a single virus particle outside a cell
D) an extracellular virus genome
E) a virus genome integrated into a host cell genome

Question 26

Plaque assays are used for

A) evaluating the cancer-causing ability of a virus.
B) determining the density of phage in a culture.
C) the study of prions.
D) cultivating viruses that cannot be grown any other way.
E) counting the number of latent phages in a cell.

Question 27

Which of the following laboratory procedures is used for culturing animal viruses in the laboratory?

A) cell cultures
B) broth cultures
C) embryonated eggs
D) both cell cultures and embryonated eggs
E) synthetic cytoplasm

Question 28

How are prions different from all other known infectious agents?

A) they cannot reproduce outside a cell.
B) they act as slow viruses.
C) they cause neurological problems.
D) they can be destroyed by incineration.
E) they lack nucleic acid.

Question 29

Which of the following virus families has a double-stranded RNA genome?

A) Retroviridae
B) Reoviridae
C) Rhadoviridae
D) Orthomyxoviridae
E) Filoviridae

Question 30

Which of the following is a feature shared by viruses and living organisms?

A) possession of a genome that directs synthesis of materials necessary for replication
B) presence of cytoplasm
C) metabolic capability
D) responsiveness
E) the ability to increase in size

Question 31

Disadvantages of continuous cell cultures include

A) they only grow for a limited number of generations.
B) the expense of preparation.
C) they may be significantly different genetically from the original source animal.
D) viruses do not reliably infect them.
E) they are both expensive and have a limited number of division.

Question 32

How is the HIV provirus different from a lambda-phage prophage?

A) the HIV provirus is integrated permanently into the host cell's DNA.
B) all subsequent generations of HIV-infected cells carry the provirus.
C) all the offspring of a cell infected with a prophage will contain the virus.
D) the HIV provirus is inactive inside the host cell.
E) lambda phage-infected cells produce virus slowly over time.

Question 33

A lipid membrane is present in which of the following?

A) naked viruses
B) enveloped viruses
C) prions
D) viroids
E) both prions and viroids

Question 34

Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated?

A) +ssRNA viruses
B) ssDNA viruses
C) -ssRNA viruses
D) retroviruses
E) dsDNA viruses

Question 35

A cell is infected with a virus carrying an oncogene sequence in its genome. What process may occur if the oncogene is expressed in the infected cell?

A) lysis
B) neoplasia
C) lysogeny
D) latency
E) both lysis and neoplasia

Question 36

Which of the following membranes can give rise to a viral envelope?

A) the nuclear membrane
B) the cytoplasmic membrane
C) the endoplasmic reticulum
D) the nuclear and cytoplasmic membranes
E) the nuclear and cytoplasmic membranes and the endoplasmic reticulum

Question 37

Reverse transcriptase is associated with which of the following?

A) dsDNA viruses
B) +ssRNA viruses
C) -ssRNA viruses
D) retroviruses
E) dsRNA viruses

Question 38

Naked capsid animal viruses are commonly released from the infected cell by ________, a process the host cell does not survive.

A) budding
B) lysis
C) endocytosis
D) membrane fusion
E) exocytosis

Question 39

The genome of which of the following types of animal virus can act directly as mRNA?

A) retroviruses
B) +ssRNA viruses
C) -ssRNA viruses
D) ssDNA viruses
E) dsRNA viruses

Question 40

One mechanism by which viruses may cause cancer is to interrupt the genetic regulatory sequences of repressor proteins. Which of the following types of viruses is most likely to be involved in causing cancer by this mechanism?

A) +ssRNA viruses
B) dsRNA viruses
C) -ssRNA viruses
D) retroviruses
E) both +ssRNA and -ssRNA viruses

Question 41

Viruses with -ssRNA require the activity of (DNA polymerase/reverse transcriptase/RNA-dependent RNA polymerase) for their replication.

Question 42

Most viruses cannot be seen by light microscopy.

Question 43

All viruses use the host cell's nucleic acid polymerases for replication.

Question 44

A ________ is a mass of neoplastic cells.

A) diploid culture
B) metastasis
C) tumor
D) gall
E) plaque

Question 45

Budding release of virus may result in long lasting or persistent infection.

Question 46

The genome of all DNA animal viruses is replicated in the nucleus of the cell.

Question 47

Viral capsids are composed of subunits called (capsomeres/nucleocapsids/prions).

Question 48

The virions shown in Figure 13.1 have a (complex/helical/polyhedral) capsid.

Question 49

The process known as ________ is a mechanism of release for enveloped viruses.

A) lytic replication
B) persistent infection
C) metastasis
D) latency
E) budding

Question 50

The combination of a virus's protein coat and nucleic acid core is called the (capsid/virion/nucleocapsid).

Question 51

Protozoa are susceptible to viral attack.

Question 52

Bovine spongiform encephalopathy is an example of a prion disease.

Question 53

Members of a virus family have the same type of nucleic acid.

Question 54

The ________ of a virion determines the type of cell it enters.

A) nucleic acid
B) matrix proteins
C) glycoproteins
D) lipid molecules
E) shape

Question 55

Which of the following infectious particles is most susceptible to damage?

A) naked capsid virus
B) enveloped virus
C) prions
D) bacteriophage
E) both naked capsid viruses and prions

Question 56

A viral infection which does not result in the production of new virions is ________ infection(s).

A) a lytic
B) a latent
C) a persistent
D) a lysogenic
E) either latent or lysogenic

Question 57

Continuous cell cultures are developed from (embryonic/haploid/neoplastic) cells.

Question 58

Bacteriophage release is a gradual process in which small numbers are released at a time.

Question 59

Viruses cause most human cancers.

Question 60

Fertilized chicken eggs are used to culture some vaccine strains.

Question 61

Uncontrolled cell division in animals is known as (metastasis/neoplasia/cancer).

Question 62

Another term for a lysogenic phage is a (temperate/latent/prophage) phage.

Question 63

A (colony/plaque/prophage) is a clear zone on a bacterial lawn where cells have been killed by the activity of a bacteriophage.

Question 64

The stage of virus infection called (assembly/entry/synthesis) is the stage most dependent on host cell proteins.

Question 65

A scientist discovers a new virus associated with a cancer. She is able to culture it in the laboratory and begins to analyze it. What features will help her determine the virus' classification? How does this help her understand the virus' mechanism for causing cancer?

Question 66

Compare and contrast the ways in which animal, plant, and bacterial viruses gain entry into their host cells.

Question 67

Seven (orders/families/classes) represent the highest level of taxonomic rank used in classifying viruses.

Question 68

Why is the synthesis of mRNA a central issue for all viruses? How do different types of viruses achieve this goal?

Question 69

RNA viruses such as HIV require the activity of reverse (polymerase/transcriptase/transposase) to become proviruses.

Question 70

Genes that play a role in proper cell division but may also play a role in some types of cancer are called (oncogenes/protooncogenes/promoters).

Question 71

Prions are composed of a single protein called (plaque/BSE/PrP).

Question 72

In contrast to most dsDNA animal viruses, the poxviruses replicate solely in the cytoplasm of the host cell. What does this suggest about the virus?

Question 73

A "naked" virus lacks (lipid/nucleic acid/protein).

Question 74

The process during viral infection known as "uncoating" involves the removal of the (capsid/envelope/matrix).

Question 75

Describe the mechanism by which PrP is infectious.