Deck 24: Viruses and Subviral Agents

Question 1

Virulent (lytic) phages:

A) infect viruses.
B) destroy bacteria.
C) infect but do not destroy bacteria.
D) infect virions.
E) infect prions.

Answer 1

B

Question 2

A prophage:

A) is phage DNA that is integrated into viral DNA.
B) is phage DNA that is integrated into bacterial DNA.
C) replicates only when the eukaryotic cell it infects replicates.
D) is an underdeveloped lytic virus.
E) is a bacterial cell about to lyse.

Answer 2

B

Question 3

The protein coat of a virus is called the:

A) capsule.
B) capsid.
C) exospore.
D) phage.
E) pilus.

Answer 3

B

Question 4

Retroviruses differ from other RNA viruses by:

A) having reverse transcriptase instead of RNA-dependent RNA polymerase.
B) the shape of their capsid.
C) the way they infect their host cells.
D) the sugar coating on their capsids.
E) lytically destroying their hosts.

Question 5

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

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

Question 6

Viruses have all the following EXCEPT

A) are usually species-specific.
B) may have multiple origins.
C) are probably related to mobile genetic elements.
D) may have escaped from cells.
E) have mitochondria

Question 7

The bacterium that causes botulism disease is harmless until it:

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

Question 8

Phages are being considered for:

A) vectors in gene therapy experiments.
B) antibiotics in bacterial infections.
C) gene transfer vectors in animal cells.
D) being equivalent to the first living organisms.
E) All of the above.

Question 9

Viruses are classified by:

A) the sequence of their DNA.
B) structural similarities.
C) the sequence of their rRNA genes.
D) the traditional Linnaean binomial nomenclature system.
E) an international committee.

Question 10

Viruses were first identified:

A) because they caused an infection and formed colonies on nutrient agar plates.
B) because they were seen in the light microscope.
C) because they caused an infection and were small enough to pass through filters that trapped bacteria.
D) because they were smaller than bacteria and had all the properties of living organisms.
E) because they caused an infection and were seen in the electron microscope.

Question 11

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

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

Question 12

Which of the following diseases is not caused by a virus?

A) rabies
B) polio
C) warts in humans
D) chickenpox
E) Lyme disease

Question 13

Viruses that attack bacteria are called:

A) phages.
B) bacteriods
C) prions.
D) virons.
E) viroids.

Question 14

Viruses:

A) are very tiny cells on the order of 500 nm.
B) contain both RNA and DNA.
C) cannot independently perform metabolic activities.
D) have a standard morphology that includes a capsid, tail, and tail fibers.
E) have nuclei.

Question 15

Temperate viruses:

A) always destroy their host immediately.
B) are considered virulent.
C) do not always destroy their host.
D) do not undergo a lysogenic cycle.
E) undergo a lytic cycle.

Question 16

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

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

Question 17

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 18

Which of the following identifies a group of DNA viruses?

A) retroviruses
B) herpesviruses
C) paramyxoviruses
D) filovirus
E) picornaviruses

Question 19

Viral proteins can damage host cells by:

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

Question 20

__________ conversion occurs when a bacterium carrying viral genes takes on new, atypical characteristics.

A) Transducing
B) Lysogenic
C) Prophage
D) Lytic
E) Reverse

Question 21

MATCHING
Match the virus group with nucleic acid description
a.ssRNA that can serve as mRNA ; enveloped viruses
d.dsDNA : nonenveloped virus
b.ssRNA enveloped viruses;contains reverse transcriptase for transcription of RNA into DNA; two identical molecules ssRNA
e.dsDNA: large complex enveloped virus virus; replicates in host nucleus
c.ssRNA that serves as template for mRNA synthesis ; medium sized enveloped that often exhibit projecting spikes
Herpesviruses

Question 22

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

Question 23

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 24

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

Question 25

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

Question 26

Pruisner concluded that the infective agent of CJD was not a virus because it was not sensitive to radiation which mutates nucleic acids.
_____________

Question 27

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

Question 28

The immunodeficiency virus that causes acquired immunodeficiency syndrome is an enveloped virus.
____________________

Question 29

Bacteriophages decrease food safety .
____________________

Question 30

MATCHING
Match the virus group with nucleic acid description
a.ssRNA that can serve as mRNA ; enveloped viruses
d.dsDNA : nonenveloped virus
b.ssRNA enveloped viruses;contains reverse transcriptase for transcription of RNA into DNA; two identical molecules ssRNA
e.dsDNA: large complex enveloped virus virus; replicates in host nucleus
c.ssRNA that serves as template for mRNA synthesis ; medium sized enveloped that often exhibit projecting spikes
Orthomyxoviruses

Question 31

__________ is credited with the discovery of prions as a new biological principle of infection.

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

Question 32

MATCHING
Match the virus group with nucleic acid description
a.ssRNA that can serve as mRNA ; enveloped viruses
d.dsDNA : nonenveloped virus
b.ssRNA enveloped viruses;contains reverse transcriptase for transcription of RNA into DNA; two identical molecules ssRNA
e.dsDNA: large complex enveloped virus virus; replicates in host nucleus
c.ssRNA that serves as template for mRNA synthesis ; medium sized enveloped that often exhibit projecting spikes
Describe the theory that attempts to explain the species specificity of viruses to their hosts.

Question 33

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

Question 34

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

Question 35

MATCHING
Match the virus group with nucleic acid description
a.ssRNA that can serve as mRNA ; enveloped viruses
d.dsDNA : nonenveloped virus
b.ssRNA enveloped viruses;contains reverse transcriptase for transcription of RNA into DNA; two identical molecules ssRNA
e.dsDNA: large complex enveloped virus virus; replicates in host nucleus
c.ssRNA that serves as template for mRNA synthesis ; medium sized enveloped that often exhibit projecting spikes
Togaviruses

Question 36

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

Question 37

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

Question 38

MATCHING
Match the virus group with nucleic acid description
a.ssRNA that can serve as mRNA ; enveloped viruses
d.dsDNA : nonenveloped virus
b.ssRNA enveloped viruses;contains reverse transcriptase for transcription of RNA into DNA; two identical molecules ssRNA
e.dsDNA: large complex enveloped virus virus; replicates in host nucleus
c.ssRNA that serves as template for mRNA synthesis ; medium sized enveloped that often exhibit projecting spikes
Papovaviruses

Question 39

MATCHING
Match the virus group with nucleic acid description
a.ssRNA that can serve as mRNA ; enveloped viruses
d.dsDNA : nonenveloped virus
b.ssRNA enveloped viruses;contains reverse transcriptase for transcription of RNA into DNA; two identical molecules ssRNA
e.dsDNA: large complex enveloped virus virus; replicates in host nucleus
c.ssRNA that serves as template for mRNA synthesis ; medium sized enveloped that often exhibit projecting spikes
Retroviruses

Question 40

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

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

Question 41

MATCHING
Match the virus group with nucleic acid description
a.ssRNA that can serve as mRNA ; enveloped viruses
d.dsDNA : nonenveloped virus
b.ssRNA enveloped viruses;contains reverse transcriptase for transcription of RNA into DNA; two identical molecules ssRNA
e.dsDNA: large complex enveloped virus virus; replicates in host nucleus
c.ssRNA that serves as template for mRNA synthesis ; medium sized enveloped that often exhibit projecting spikes
Discuss and compare the hypotheses for the evolution of viruses