Deck 24: Viruses and Subviral Agents

Question 1

What is the correct unit of measurement for the size of most viruses?

A) picometers
B) nanometers
C) micrometers
D) centimeters
E) decimeters

Answer 1

B

Question 2

Viral infections in humans spread via the circulatory system. Viral infections in plants spread from cell to cell via:

A) pili.
B) endocytosis.
C) infected seeds.
D) plasmodesmata.
E) transformation.

Answer 2

D

Question 3

Which statement describes a virulent phage?

A) A virulent phage infects viruses.
B) A virulent phage infects prions.
C) A virulent phage infects virions.
D) A virulent phage destroys bacteria.
E) A virulent phage infects but does not destroy bacteria.

Answer 3

D

Question 4

The five stages of a lytic infection are attachment, penetration, __________, assembly, and release.

A) lysis
B) prophage
C) replication
D) lysogenesis
E) transduction

Question 5

The ____ classification system classifies viruses based on the type of nucleic acid the virus contains.

A) Linnaean
B) Mendelian
C) Baltimore
D) Philadelphia
E) International Committee on Taxonomy of Viruses

Question 6

Which characteristic defines a virus?

A) Viruses cannot replicate.
B) Viruses cannot metabolize.
C) Viruses contain both RNA and DNA.
D) Viruses have various morphologies.
E) Viruses are very tiny cells with nuclei.

Question 7

At what stage of the lysogenic cycle would a prophage appear?

A) penetration
B) integration
C) attachment
D) replication
E) assembly

Question 8

Which statement describes a temperate virus?

A) A temperate virus undergoes a lytic cycle.
B) A temperate virus is considered virulent.
C) A temperate virus does not always destroy its host.
D) A temperate virus does not undergo a lysogenic cycle.
E) A temperate virus always destroys their host immediately.

Question 9

What is a prophage?

A) It is a bacterial cell about to lyse.
B) It is an underdeveloped lytic virus.
C) It is phage DNA that is integrated into viral DNA.
D) It is phage DNA that is integrated into bacterial DNA.
E) It is when the phage is attached to the cell surface of the bacterium.

Question 10

What type of conversion occurs when a bacterium carrying viral genes takes on new, atypical characteristics?

A) transducing
B) lysogenic
C) prophage
D) reverse
E) lytic

Question 11

What is the purpose of phage therapy?

A) To supplement gene therapy
B) To build antibiotic resistance
C) To target and destroy cancer cells
D) To improve replication of other viruses
E) To target specific bacteria in the body and destroy them

Question 12

What is the protein coat of a virus called?

A) envelope
B) capsule
C) capsid
D) phage
E) pilus

Question 13

Viral proteins can damage host cells by which process?

A) producing endotoxins
B) preventing transcription of viral nucleic acids
C) increasing the rate of fermentation within the host
D) causing a decline in coordination and increased irritability
E) overwhelming the host cell with a large number of viruses.

Question 14

Figure 24-1d Refer to the accompanying figure. What is the function of the structure labeled as 3?

A) replication
B) locomotion
C) mate recognition
D) attachment to a host cell
E) to take over host cell mechanisms

Question 15

Which statement about viruses is FALSE ?

A) Viruses are not cellular.
B) Viruses can manufacture proteins.
C) Viruses cannot carry on metabolic activities.
D) Viruses can only replicate by infecting other cells.
E) Viruses have a protective protein coat called a capsid.

Question 16

Human viruses can enter human cells by fusion with the cell membrane or by:

A) endocytosis.
B) diffusion into the cell.
C) passage through specific protein channels.
D) attaching onto protein signals entering the cell.
E) coating themselves with lipids that cloak their entrance into the cell.

Question 17

Figure 24-1d Which structure of the virus in the accompanying figure is the capsid?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 18

At what stage of a lytic infection are phage components put together to make new viruses?

A) replication and synthesis
B) penetration
C) attachment
D) assembly
E) release

Question 19

What are the viruses that attack bacteria?

A) phages
B) virons
C) prions
D) satellites
E) adenoviruses

Question 20

How are viruses classified by the ICTV?

A) By their DNA sequence
B) By their number of rRNA
C) By their structural components
D) By their host range and other characteristics
E) By the Linnaean binomial nomenclature system

Question 21

Which has an unusual characteristic in that their circular DNA does not have genes for making the proteins needed to replicate and produce new viruses?

A) viroid
B) retroviruses
C) bacteriophages
D) pandoraviruses
E) polydnaviruses

Question 22

The immunodeficiency virus that causes acquired immunodeficiency syndrome is a(n) enveloped virus.
____________________

Question 23

Before an animal cell's membrane fuses with a virus, the virus must first:

A) duplicate its DNA.
B) use enzymes of the plasma membrane to break down its capsid.
C) replicate itself to attack numerous sites of the plasma membrane.
D) extend its tail fibers to sense the plasma membrane of the host cell.
E) attach to a specific receptor on the plasma membrane of the host cell.

Question 24

According to the progressive hypothesis , viruses may have originated as mobile genetic elements such as:

A) mRNA.
B) alleles.
C) plasmids.
D) enzymes.
E) ribosomes.

Question 25

The specificity of viruses to different types of cells is due to ____ sites on the host cell.

A) prophage
B) receptor
C) transduction
D) penetration
E) transcription

Question 26

What is the difference between a viral lytic cycle and a viral lysogenic cycle?

Question 27

Mad cow disease is an example of an infection caused by a:

A) bacteriophage.
B) bacterium.
C) retrovirus.
D) viroid.
E) prion.

Question 28

How do retroviruses differ from other RNA viruses?

A) Retroviruses have a unique capsid shape.
B) Retroviruses lytically destroy their hosts.
C) Retroviruses have a unique infection technique of their host cells.
D) Retroviruses have a capsid composed of protein and carbohydrates.
E) Retroviruses have reverse transcriptase instead of RNA-dependent RNA polymerase.

Question 29

Which hypothesis asserts that viruses are remnants of cellular organisms and evolved from small cells that were parasites in larger cells?

A) escape hypothesis
B) virus-first hypothesis
C) regressive hypothesis
D) progressive hypothesis
E) degenerative hypothesis

Question 30

Viroids cause a variety of plant diseases and are composed only of:

A) strands of RNA.
B) strands of DNA.
C) protein coats.
D) peptidoglycan.
E) a capsid.

Question 31

Which of the following identifies a group of RNA viruses?

A) Poxviruses
B) Herpesviruses
C) Papovaviruses
D) Adenoviruses
E) Paramyxoviruses

Question 32

Why can measles virus and poxvirus infect many human tissues and influenza virus can infect only one type of tissue?

Question 33

The genome of most plant viruses consists of what kind of RNA?

A) rRNA
B) mRNA
C) ssRNA
D) dsRNA
E) SRP RNA

Question 34

Who is credited with the discovery of prions as a new biological principle of infection?

A) Anton van Leeuwenhoek
B) Dmitrii Ivanowsky
C) Stanley Prusiner
D) Stanley Brenner
E) Carl Woese

Question 35

List and describe the structures of viruses.

Question 36

Which is a symptom of a transmissible spongiform encephalopathy (TSE)?

A) influenza-like symptoms
B) progressive immune deficiency
C) degeneration of the digestive tract
D) inflammation of the reproductive organs
E) degeneration of the brain and central nervous system

Question 37

The bacterium that causes botulism disease is harmless until it:

A) is infected by prions.
B) is infected by lytic bacteria.
C) is irradiated by UV radiation.
D) contains a certain prophage DNA.
E) is infected by certain retroviruses.

Question 38

Which of the following diseases is a DNA virus?

A) polio
B) rabies
C) measles
D) smallpox
E) influenza

Question 39

What does ss DNA stand for?

A) s ingle s tranded DNA
B) s imple s atellite DNA
C) s ingle s ynthesis DNA
D) s imple s ynthase DNA
E) s ynthetic strand DNA

Question 40

A virus consists of a DNA or RNA core surrounded by a(n) envelope .
____________________

Question 42

Prions induce normal Prp on the surface of brain cells to misfold into a(n) insoluble form and cause brain damage.
____________________

Question 43

Bacteriophages decrease food safety .
____________________

Question 44

Compare and contrast the three hypotheses which explain the evolution of viruses

Question 45

Dr. Stanley Prusiner concluded that the infective agent of CJD was not a(n) virus because it was not sensitive to radiation which mutates nucleic acids.
____________________

Question 46

Bacteriophages attach to the cell walls of bacteria by envelope proteins. ____________________

Question 47

The genomes of most plant viruses consist of single stranded DNA . ____________________

Question 48

Bacteria protect themselves from bacteriophage infections by producing restriction enzymes that cut up foreign RNA of the phage.
____________________

Question 49

Retroviruses have a(n) DNA polymerase called reverse transcriptase, which transcribes the RNA genome into a DNA intermediate.
____________________

Question 50

The agent that causes hepatitis D is a(n) viroid that can only reproduce when the hepatitis B virus is also present.
____________________

Question 51

Describe the theory that attempts to explain the species specificity of viruses to their hosts.