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

Question 1

During , viruses remain dormant in animal cells.

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

Answer 1

A

Question 2

Small circular RNA molecules without capsids are characteristic of

A) viruses and prions.
B) plasmids.
C) prions.
D) viruses.
E) viroids.

Answer 2

E

Question 3

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

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

Answer 3

B

Question 4

How are fungal viruses different from viruses that infect other organisms?

A) They have only DNA for genetic material.
B) They have no capsid.
C) They have no extracellular state.
D) They have no intracellular state.
E) They cannot pass through a filter.

Question 5

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

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

Question 6

A is a mass of neoplastic cells.

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

Question 7

In what ways do viruses differ from other pathogens?

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

Question 8

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

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

Question 9

The viruses of fungi have RNA genomes and lack a capsid. They are therefore similar to

A) bacteriophages.
B) prions.
C) enveloped viruses.
D) viroids.
E) lysogens.

Question 10

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

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

Question 11

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

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

Question 12

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

Question 13

Tumors invade other organs and tissues in a process called

A) a plaque assay.
B) neoplasia.
C) latency.
D) budding.
E) metastasis.

Question 14

In contrast to most dsDNA animal viruses, the poxviruses replicate solely in the cytoplasm of the host cell. This fact implies that the viral genome may encode

A) reverse transcriptase and RNA- dependent RNA transcriptase.
B) ribosome components.
C) RNA- dependent RNA transcriptase.
D) reverse transcriptase.
E) a DNA polymerase.

Question 15

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

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

Question 16

A lipid membrane is present in which of the following?

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

Question 17

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

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

Question 18

Host specificity of a virus is due to

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

Question 19

Diploid cell cultures and continuous cell cultures differ in which of the following ways?

A) convenience of use
B) source of cells
C) longevity
D) both longevity and convenience of use
E) both longevity and source of cells

Question 20

Double- stranded RNA genomes can be found

A) only in cells.
B) only in prions.
C) in both cells and viruses.
D) in both prions and viruses.
E) only in viruses.

Question 21

Which of the following places stages of a lytic replication cycle in order, from earliest to latest stages?

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

Question 22

Viruses are shed slowly and steadily during

A) oncogenesis.
B) lytic replication.
C) latency.
D) budding.
E) lysogenic infection.

Question 23

The genome of which of the following types of animal virus can act directly as mRNA?
A) - ssRNA viruses

A) retroviruses
B) dsRNA viruses
B) ssDNA viruses
C) +ssRNA viruses

Question 24

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

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

Question 25

Which of the following types of animal virus requires RNA- dependent RNA transcriptase to be replicated?
A) +ssRNA viruses

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

Question 26

Viroids infect

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

Question 27

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

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

Question 28

Reverse transcriptase is associated with which of the following?
A) dsRNA viruses

A) retroviruses
B) - ssRNA viruses
B) dsDNA viruses
C) +ssRNA viruses

Question 29

Zones of clearing in cell cultures that are the result of virus infection are called plaques. Sometimes "cloudy plaques" are seen on bacterial cultures infected with bacteriophage. What type of viral infection might cause this appearance?

A) lysogenic
B) viroid
C) lytic
D) transducing
E) prion

Question 30

Which of the following statements regarding virus taxonomy is true?

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

Question 31

Which of the following statements comparing virus classification and taxonomy of organisms is true?

A) Both viruses and organisms are organized into domains.
B) Only families are common to both viral classification and organism taxonomy.
C) The common names of viruses are their genus and species epithet, as they are with organisms.
D) Genus and specific epithet are used in both classification systems.
E) Both viruses and organisms are organized into classes.

Question 32

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

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

Question 33

Which means of entry into host cells is common to both some animal viruses and bacteriophage T4?

A) membrane fusion
B) endocytosis
C) direct penetration
D) both endocytosis and direct penetration
E) endocytosis, direct penetration, and membrane fusion

Question 34

Why is lysogeny advantageous to a bacteriophage?

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

Question 35

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

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

Question 36

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

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

Question 37

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

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

Question 38

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

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

Question 39

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

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

Question 40

Plaque assays are used for

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

Question 41

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

Question 42

How are prions different from all other known infectious agents?

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

Question 43

The virions shown in the figure have a (polyhedral/helical/complex) capsid.

Question 44

Virus replication results in the death of the cell in infection(s).

A) a lysogenic
B) a lytic
C) a latent
D) a persistent
E) both latent and persistent

Question 45

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 46

Which of the following is matched INCORRECTLY?

A) poliovirus; direct penetration
B) adenovirus; membrane fusion
C) measles virus; membrane fusion
D) herpesvirus; endocytosis
E) HIV; membrane fusion

Question 47

Some viruses can be cultured on (continuous/diploid/animal) cells which are descended from neoplastic cells.

Question 48

In enveloped viruses, virus- encoded (matrix/capsomeres/envelope) proteins are required for the assembly of the envelope around the capsid.

Question 49

The process in which viral capsids are removed within the infected cell is called (entry/disassembly/uncoating).

Question 50

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

Question 51

Virus infection is initiated by the specific (fit/affinity/interaction) between proteins on the surface of a virion the surface of the target cell.

Question 52

Some human viruses are difficult to study because

A) they establish latent infections and cannot be induced.
B) the growth medium for the host cells is complex.
C) very few laboratories have the skills to culture the viruses.
D) they grow very slowly.
E) they only grow in normal human cells.

Question 53

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

Question 54

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

Question 55

Which of the following may occur in a lysogenic infection, but not a latent one?

A) The viral DNA integrates (inserts) into the host cell DNA.
B) The inserted viral DNA may leave the host DNA.
C) The provirus/prophage directs the synthesis of viral proteins.
D) The prophage/provirus is replicated with the host DNA.
E) The prophage/provirus alters gene expression in the host cell.

Question 56

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

Question 57

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

Question 58

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

Question 59

An animal virus that does not have an envelope is described as a(n) (naked/unenveloped/capsid) virion.

Question 60

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

Question 61

Fertilized chicken eggs are used to culture some vaccine strains.

Question 62

Protozoa are susceptible to viral attack.

Question 63

Assembly of new viruses is a process that usually requires the direction of a variety of viral and cellular enzymes.

Question 64

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

Question 65

Describe the difference between lysogeny and latency.

Question 66

All members of a virus family have the same type of genome structure.

Question 67

Bovine spongiform encephalopathy is an example of a prion disease.

Question 68

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 69

Viruses cause most human cancers.

Question 70

Most viruses cannot be seen by light microscopy.

Question 71

Many diseases of plants are caused by infectious RNA molecules lacking capsids.

Question 72

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

Question 73

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

Question 74

Describe the mechanism by which PrP is infectious.

Question 75

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