Which of the following statements concerning viruses is FALSE?

Viruses enter a cell to complete the replication they have begun extracellularly

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

protection and recognition

During the intracellular state, a virus exists as

a nucleic acid

Viruses are primarily classified according to their

type of nucleic acid

Host specificity of a virus is due to

interactions between viral and cellular surface molecules

Who was the first person to demonstrate the existence of viruses?

Ivanowsky

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

They have no extracellular state

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

viroids

Which of the following would NOT be found as a component of a bacteriophage?

envelope

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.

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

Genus and specific epithet are used in both classification systems

Put the following stages of a lytic replication cycle in order, from earliest to latest stages:

Attachment, Entry, Synthesis, Assembly, and Release

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

random collisions, chemical attractions, and receptor specificity

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

entry and release

The phenomenon of transduction is associated with which of the stages of a bacteriophage infection cycle?

assembly

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

digestion of host DNA

Why is lysogeny advantageous to a bacteriophage?

The genetic material of the bacteriophage can be passed on to future generations of cells

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

UV light and X rays

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?

lysogenic

Which of the following is matched INCORRECTLY?

adenovirus — membrane fusion

Reverse transcriptase is associated with which of the following?

retroviruses

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

+ssRNA viruses

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

-ssRNA viruses

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 DNA polymerase

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

the nuclear and cytoplasmic membranes and the endoplasmic reticulum

The majority of cases of infant diarrhea are caused by what kind of virus?

dsRNA viruses

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

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

Which of the following individuals discovered prions?

Prusiner

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?

retroviruses

Tumors invade other organs and tissues in a process called

metastasis

Plaque assays are used for

estimating the number of phages in a culture

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

longevity and source of cells

Viroids infect

plants

How are prions different from all other known infectious agents?

They lack nucleic acid

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

viroids

A lipid membrane is present

in both cells and viruses

Double-stranded RNA genomes can be found

only in viruses

Cytoplasm is a characteristic of

Cells only

Proteins are present in

both cells and viruses

Viruses are shed slowly and steadily during

persistent infection

During __________, viruses remain dormant in a cell

latency

Virus replication results in the death of the cell in a(n) __________ infection

lytic

Virus infection results in cancer in the process of

oncogenesis

is a mechanism of release for enveloped viruses

Budding

Viruses cause most human cancers

FALSE

Most viruses cannot be seen by light microscopy

TRUE

Protozoa are susceptible to viral attack

TRUE

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

TRUE

Bacteriophages are cheaper and easier to culture than animal viruses

TRUE

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

FALSE

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

FALSE

Poxvirus is assembled in the cytoplasm of the cell instead of in the nucleus, as is the case for

TRUE

Transcription of RNA from RNA does not occur in uninfected cells

TRUE

Virus vaccines are always cultured in embryonated chicken eggs

FALSE