question

Which of the following is an accurate description of a virion? a population of infectious particles an infectious particle of protein and nucleic acid outside a host cell the nucleic acid of a viral pathogen the protein portion of a viral particle the nucleic acid of a viral pathogen inside a host cell

answer

an infectious particle of protein and nucleic acid outside a host cell

question

The outermost layer of a virion fulfills which of the following functions of the virus? protection replication recognition both protection and recognition both recognition and replication

answer

both protection and recognition

question

A ________ is a virus that infects bacterial cells. prion nucleocapsid bacteriophage virion viroid

answer

bacteriophage

question

Which of the following is present in cells only during virus infection? DNA-RNA heteroduplex ssRNA triplet RNA ssDNA dsDNA

answer

ssDNA

question

Host specificity of a virus is due to particular genes that it shares with the infected cell. the presence of an envelope. the presence or absence of a cell wall on the host cell. differences in size between the virus and the host cell. interactions between viral and cellular surface molecules.

answer

interactions between viral and cellular surface molecules.

question

The shape of a virion is a function of the ________ of the virus. type of genome material capsid cell type of the host cell size of the genome material envelope

answer

capsid

question

How are fungal viruses different from viruses that infect other organisms? they have only DNA for genetic material. they have no intracellular state. they have no extracellular state. they cannot pass through a filter. they have no capsid.

answer

they have no extracellular state.

question

The envelope portion of an enveloped virus is composed of glycolipids of the host cell. host glycolipids and virus-encoded glycoproteins. host cell membranes containing virus-encoded glycoproteins. phospholipids from host cell membranes. virus-encoded glycoproteins.

answer

host cell membranes containing virus-encoded glycoproteins.

question

Which of the following may occur in a lysogenic infection, but NOT a latent one? The inserted viral DNA may leave the host DNA. The provirus/prophage directs the synthesis of viral proteins. The prophage/provirus alters gene expression in the host cell. The prophage/provirus is replicated with the host DNA. The viral DNA integrates (inserts) into the host cell DNA.

answer

The inserted viral DNA may leave the host DNA.

question

Which of the following statements regarding virus taxonomy is TRUE? Some virus family names are derived from the name of an important member of the family. Viruses are classified on the basis of the taxonomy of their host organisms. Virus classes are well established. Virus classes are based on the domain of the host organism. The species epithet is a latin descriptor of the virion structure.

answer

Some virus family names are derived from the name of an important member of the family.

question

Classification of viruses includes orders. classes. families. orders and families. classes, orders, and families.

answer

orders and families.

question

What is the correct order for the stages of a lytic replication cycle, from earliest to latest stages? I. Synthesis II. Assembly III. Attachment IV. Release V. Entry III, V, I, II, IV I, III, V, II, IV I, II, III, V, IV III, II, V, I, IV V, III, II, IV, I

answer

III, V, I, II, IV

question

Which of the following is involved in the attachment of a bacteriophage to a bacterial cell? chemical attractions random collisions receptor specificity both chemical attractions and receptor specificity random collisions, chemical attractions, and receptor specificity

answer

random collisions, chemical attractions, and receptor specificity

question

The enzyme lysozyme is critical for which of the stages of a bacteriophage T4 infection cycle? synthesis entry and release assembly entry attachment

answer

entry and release

question

Naked capsid animal viruses gain entry to host cells by endocytosis. direct penetration. membrane fusion. both endocytosis and direct penetration. endocytosis, direct penetration, and membrane fusion.

answer

both endocytosis and direct penetration.

question

Which of the following events occurs in the lytic cycle of bacteriophage T4 infection but not in the lysogenic cycle? viral protein synthesis attachment entry digestion of host DNA both digestion of host DNA and viral proteins synthesis

answer

digestion of host DNA

question

Why is lysogeny advantageous to a bacteriophage? it enables the bacteriophage to take over the cell. the genetic material of the bacteriophage is amplified many times over that seen in a lytic phage. it allows the bacteriophage to destroy the host cell's DNA. it speeds up the viral infection cycle. it allows the bacteriophage to infect cells it would not normally infect.

answer

the genetic material of the bacteriophage is amplified many times over that seen in a lytic phage.

question

Which of the following agents is capable of inducing conversion of a prophage to the lytic cycle? presence of +ssRNA UV light X-rays both UV light and X-rays both UV light and the presence of +ssRNA

answer

both UV light and X-rays

question

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? lytic transducing lysogenic viroid prion

answer

lysogenic

question

Which virus is CORRECTLY matched with its method of entry? poliovirus; endocytosis adenovirus; direct penetration HIV; membrane fusion measles virus; direct penetration herpesvirus; membrane fusion

answer

HIV; membrane fusion

question

Retroviruses require the activity of ________ to complete their infection cycle. viral RNA polymerase RNA-dependent RNA transcriptase lysozyme RNA-dependent RNA polymerase reverse transcriptase

answer

reverse transcriptase

question

The genome of which of the following types of animal virus can act directly as mRNA? dsDNA dsRNA viruses ssDNA viruses -ssRNA viruses +ssRNA viruses

answer

+ssRNA viruses

question

Which of the following types of animal virus requires RNA-dependent RNA transcriptase to be replicated? -ssRNA viruses +ssRNA viruses retroviruses ssDNA viruses dsDNA viruses

answer

-ssRNA viruses

question

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 RNA-dependent RNA transcriptase. reverse transcriptase. ribosome components. a DNA polymerase. reverse transcriptase and RNA-dependent RNA transcriptase.

answer

a DNA polymerase.

question

Which of the following membranes can give rise to a viral envelope? the cytoplasmic membrane the endoplasmic reticulum the nuclear membrane the nuclear and cytoplasmic membranes the nuclear and cytoplasmic membranes, and the endoplasmic reticulum

answer

the nuclear and cytoplasmic membranes, and the endoplasmic reticulum

question

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? lysis lysogeny neoplasia latency both lysis and neoplasia

answer

neoplasia

question

How is the HIV provirus different from a lambda-phage prophage? lambda phage-infected cells produce virus slowly over time. the HIV provirus is integrated permanently into the host cell's DNA. all the offspring of a cell infected with a prophage will contain the virus. all subsequent generations of HIV-infected cells carry the provirus. the HIV provirus is inactive inside the host cell.

answer

the HIV provirus is integrated permanently into the host cell's DNA.

question

The process of metastasis results from benign tumors. neoplasia. oncogene expression. malignant tumors. viral latency.

answer

malignant tumors

question

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? +ssRNA viruses dsRNA viruses retroviruses -ssRNA viruses both +ssRNA and -ssRNA viruses

answer

retroviruses

question

The development of a cancerous cell is said to require "multiple hits." This means multiple cell cycle regulators are inactivated at once. a series of separate events over time lead to the loss of cell cycle regulation. several protoncogenes are activated at the same time. the cell must be infected with several different types of viruses to be transformed. multiple oncogenic viruses infect the cell at the same time.

answer

a series of separate events over time lead to the loss of cell cycle regulation.

question

Plaque assays are used for cultivating viruses that cannot be grown any other way. evaluating the cancer-causing ability of a virus. determining the density of phage in a culture. counting the number of latent phages in a cell. the study of prions.

answer

determining the density of phage in a culture.

question

Diploid cell cultures and continuous cell cultures differ in which of the following ways? source of cells convenience of use longevity both longevity and convenience of use both longevity and source of cells

answer

both longevity and source of cells

question

What is one of the most difficult aspects of studying animal viruses? The viruses are extremely dangerous to handle. The use of animals is expensive, and unethical to many people. The use of animals to study the viruses is unethical in the eyes of many. The study requires expensive facilities. The viruses are hard to obtain.

answer

The use of animals is expensive, and unethical to many people.

question

How are prions different from all other known infectious agents? they act as slow viruses. they cause neurological problems. they lack nucleic acid. they can be destroyed by incineration. they cannot reproduce outside a cell.

answer

they lack nucleic acid.

question

The viruses of fungi have RNA genomes and lack a capsid. They are therefore similar to viroids. enveloped viruses. bacteriophages. lysogens. prions.

answer

viroids.

question

Infection with ________ is likely to result in destruction of the host cell by lysis. viroids prions oncogenic viruses naked viruses enveloped viruses

answer

naked viruses

question

Some human viruses are difficult to study because very few laboratories have the skills to culture the viruses. they establish latent infections and cannot be induced. they grow very slowly. they only grow in normal human cells. the growth medium for the host cells is complex.

answer

they only grow in normal human cells.

question

Why are diploid cell cultures preferred over continuous cell cultures? Results from continuous culture cells do not apply to disease in whole organisms. Diploid cells last far longer than continuous culture cells. Continuous cell cultures are expensive to maintain. Diploid cells have undergone changes in their chromosome structure that make them more stable. Diploid cells are more nearly like cells of whole organisms than continuous culture cells.

answer

Diploid cells are more nearly like cells of whole organisms than continuous culture cells.

question

Which of the following is a feature shared by viruses and living organisms? the ability to increase in size presence of cytoplasm possession of a genome that directs synthesis of materials necessary for replication metabolic capability responsiveness

answer

possession of a genome that directs synthesis of materials necessary for replication

question

Small circular RNA molecules without capsids are characteristic of viruses. viroids. plasmids. prions. viruses and prions.

answer

viroids

question

Prions cause disease in fungi. mammals. bacteria. birds. plants.

answer

mammals

question

During ________, viral synthesis is suspended. oncogenesis budding latency lytic replication persistent infection

answer

latency

question

Virus replication results in the death of the cell in ________ infection(s). a lytic a lysogenic a persistent a latent both latent and persistent

answer

a lytic

question

A ________ is a mass of neoplastic cells. metastasis tumor plaque diploid culture gall

answer

tumor

question

The process known as ________ is a mechanism of release for enveloped viruses. metastasis persistent infection latency budding lytic replication

answer

budding

question

Viruses cause most human cancers. True False

answer

False

question

Virus entry requires the presence of specific cell structures. True False

answer

True

question

Protozoa are susceptible to viral attack. True False

answer

True

question

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

answer

True

question

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

answer

True

question

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

answer

False

question

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

answer

False

question

Bovine spongiform encephalopathy is an example of a prion disease. True False

answer

True

question

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

answer

False

question

Fertilized chicken eggs are used to culture some vaccine strains. True False

answer

True

question

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

answer

nucleocapsid

question

Assembly of enveloped viruses requires (membrane/matrix/receptor) to bring together the nucleocapsid and the envelope.

answer

matrix

question

The first virus isolated, Tobacco mosaic virus, has a (complex/helical/polyhedral) capsid morphology, which facilitated its isolation.

answer

helical

question

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

answer

continuous

question

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

answer

complex

question

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

answer

temperate

question

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

answer

uncoating

question

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

answer

neoplasia

question

The graph in the figure shows a pattern of virion abundance consistent with a (lytic/latent/persistent) virus infection cycle.

answer

persistent

question

Viruses are responsible for (all/most/some) human cancers. (Use relative terms not numbers.)

answer

some

question

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).

answer

protooncogenes

question

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

answer

plaque

question

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

answer

orders

question

RNA dependent RNA polymerase is required for successful infection by (+ssRNA/-ssRNA/dsRNA) viruses.

answer

-ssRNA

question

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

answer

naked

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