Question 1

Explain why HIV becomes resistant so quickly when a single drug is used therapeutically.

Accepted Answer

A)  The virus is an RNA genome virus-by using host RNA polymerase to directly copy the genome to make more virus particles, there's no proofreading capability. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. 
B)  HIV utilizes reverse transcriptase to make a cDNA version of its RNA genome. This polymerase is 'sloppy,' with a high rate of error and lack of a proofreading capability. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. 
C)  HIV synthesizes a protein enzyme that directly cleaves anti-HIV drugs, giving it a characteristically high rate of resistance to a single drug type. 
D)  HIV is constantly changing its genetic structure by swapping genetic elements with other virus strains. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. 
A)  The virus is an RNA genome virus-by using host RNA polymerase to directly copy the genome to make more virus particles, there's no proofreading capability. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. 
B)  HIV utilizes reverse transcriptase to make a cDNA version of its RNA genome. This polymerase is 'sloppy,' with a high rate of error and lack of a proofreading capability. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance. 
C)  HIV synthesizes a protein enzyme that directly cleaves anti-HIV drugs, giving it a characteristically high rate of resistance to a single drug type. 
D)  HIV is constantly changing its genetic structure by swapping genetic elements with other virus strains. This leads to a high rate of mutation of the viral genome and increased chance for drug resistance.

Question 2

The term "segmented" refers to viruses that

Accepted Answer

A)  may contain several pieces of RNA. 
B)  have an icosahedral-shaped capsid. 
C)  are linked together before budding out. 
D)  have an envelope. 
A)  may contain several pieces of RNA. 
B)  have an icosahedral-shaped capsid. 
C)  are linked together before budding out. 
D)  have an envelope.

Question 3

For which of the following processes are enzymes not required?

Accepted Answer

A)  replication 
B)  translation 
C)  maturation 
D)  self-assembly 
A)  replication 
B)  translation 
C)  maturation 
D)  self-assembly

Question 4

After growth in tissue culture, the infected cells lyse and the virus may be harvested from

Accepted Answer

A)  the liquid supernatant after centrifugation, the lysate. 
B)  the remainder. 
C)  the quantal layer. 
D)  the monolayer. 
A)  the liquid supernatant after centrifugation, the lysate. 
B)  the remainder. 
C)  the quantal layer. 
D)  the monolayer.

Question 5

Why are viroids resistant to nucleases?

Accepted Answer

A)  Having a circular RNA 'genome,' they are resistant to the digestion of most exonucleases (that nibble/digest the free ends of RNA or DN
A) . 
B)  Having a circular RNA 'genome,' with no protein shell, they are resistant to the protein-degrading activities of nucleases. 
C)  Nucleases will only digest DNA, not RNA-so viroids are protected. 
D)  Viroids have only been identified in plants. Plant nucleases cannot digest RNA. 
A)  Having a circular RNA 'genome,' they are resistant to the digestion of most exonucleases (that nibble/digest the free ends of RNA or DN
A) . 
B)  Having a circular RNA 'genome,' with no protein shell, they are resistant to the protein-degrading activities of nucleases. 
C)  Nucleases will only digest DNA, not RNA-so viroids are protected. 
D)  Viroids have only been identified in plants. Plant nucleases cannot digest RNA.

Question 6

Plant viruses may be transmitted by

Accepted Answer

A)  worms. 
B)  contaminated seeds. 
C)  humans. 
D)  insects. 
E)  All of the choices are correct. 
A)  worms. 
B)  contaminated seeds. 
C)  humans. 
D)  insects. 
E)  All of the choices are correct.

Question 7

Animal viruses are divided into a number of families whose names end in

Accepted Answer

A)  -virus. 
B)  -viridae. 
C)  -viscous. 
D)  -eieio. 
A)  -virus. 
B)  -viridae. 
C)  -viscous. 
D)  -eieio.

Question 8

Electron microscopy is useful for counting viruses and distinguishing between infective and non-infective virions.

Accepted Answer

A) True 
 B)False

Question 9

Viruses that infect bacteria are referred to as

Accepted Answer

A)  viralcidens. 
B)  bacteriocidins. 
C)  bacterialogens. 
D)  bacteriophages. 
A)  viralcidens. 
B)  bacteriocidins. 
C)  bacterialogens. 
D)  bacteriophages.

Question 10

Which does not refer to the shape of a virus?

Accepted Answer

A)  icosahedral (isometric) 
B)  helical 
C)  complex 
D)  bacillus 
A)  icosahedral (isometric) 
B)  helical 
C)  complex 
D)  bacillus

Question 11

If reasonably pure preparations of virus are available, the number of virus present may be determined by

Accepted Answer

A)  photocolorimetry. 
B)  gas chromatography. 
C)  light microscopy. 
D)  electron microscopy. 
A)  photocolorimetry. 
B)  gas chromatography. 
C)  light microscopy. 
D)  electron microscopy.

Question 12

Naked and enveloped viruses both may enter the host via endocytosis.

Accepted Answer

A) True 
 B)False

Question 13

The best-known examples of viruses that cause latent infections are

Accepted Answer

A)  polio. 
B)  herpes. 
C)  measles. 
D)  chickenpox. 
E)  herpes AND chickenpox. 
A)  polio. 
B)  herpes. 
C)  measles. 
D)  chickenpox. 
E)  herpes AND chickenpox.

Question 14

The terms isometric, icosahedral and pleomorphic refer to

Accepted Answer

A)  viral life cycles. 
B)  forms of nucleic acid. 
C)  types of viral envelopes. 
D)  shapes of viruses. 
A)  viral life cycles. 
B)  forms of nucleic acid. 
C)  types of viral envelopes. 
D)  shapes of viruses.

Question 15

Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why?

Accepted Answer

A)  Plasmids-they're smaller, so they'd be easier to replicate by the host cell. 
B)  Integrated-the host cell would be less likely to view this DNA as 'foreign' on subsequent rounds of replication, and would retain it more easily. 
C)  Plasmids-these structures often carry other genes that may give the host cell a selective advantage over cells that don't have them. 
D)  Integration-because plasmids are frequently lost in the first round of binary fission, which could leave a cell without the virus genome. 
A)  Plasmids-they're smaller, so they'd be easier to replicate by the host cell. 
B)  Integrated-the host cell would be less likely to view this DNA as 'foreign' on subsequent rounds of replication, and would retain it more easily. 
C)  Plasmids-these structures often carry other genes that may give the host cell a selective advantage over cells that don't have them. 
D)  Integration-because plasmids are frequently lost in the first round of binary fission, which could leave a cell without the virus genome.

Question 16

Regarding phage replication,

Accepted Answer

A)  the majority of phages are temperate. 
B)  when integrated into host DNA, the phage DNA is called a prophage. 
C)  lambda is a good example of a temperate phage. 
D)  All of the choices are correct. 
A)  the majority of phages are temperate. 
B)  when integrated into host DNA, the phage DNA is called a prophage. 
C)  lambda is a good example of a temperate phage. 
D)  All of the choices are correct.

Question 17

Which of the following is not a characteristic of normal cells?

Accepted Answer

A)  They grow as a monolayer. 
B)  They grow as multiple layers. 
C)  They undergo a limited number of divisions and then die. 
D)  They stick tightly to the surface of glass culture dishes. 
A)  They grow as a monolayer. 
B)  They grow as multiple layers. 
C)  They undergo a limited number of divisions and then die. 
D)  They stick tightly to the surface of glass culture dishes.

Question 18

Carriers

Accepted Answer

A)  may have a persistent infection. 
B)  may be a source of infection. 
C)  usually show symptoms of the disease. 
D)  have been cured of the infection. 
E)  may have a persistent infection AND may be a source of infection. 
A)  may have a persistent infection. 
B)  may be a source of infection. 
C)  usually show symptoms of the disease. 
D)  have been cured of the infection. 
E)  may have a persistent infection AND may be a source of infection.

Question 19

Assembly of the T4 phage

Accepted Answer

A)  may involve some self-assembly. 
B)  may involve the use of scaffolds. 
C)  is completely self-assembly. 
D)  is completely dependent on scaffolds. 
E)  may involve some self-assembly AND may involve the use of scaffolds. 
A)  may involve some self-assembly. 
B)  may involve the use of scaffolds. 
C)  is completely self-assembly. 
D)  is completely dependent on scaffolds. 
E)  may involve some self-assembly AND may involve the use of scaffolds.

Question 20

The enveloped viruses typically obtain their envelope

Accepted Answer

A)  from the host plasma membrane. 
B)  as they exit the host. 
C)  from a newly constructed viral-derived membrane. 
D)  from the nuclear membrane. 
E)  from the host plasma membrane AND as they exit the host. 
A)  from the host plasma membrane. 
B)  as they exit the host. 
C)  from a newly constructed viral-derived membrane. 
D)  from the nuclear membrane. 
E)  from the host plasma membrane AND as they exit the host.

Exam 13: Viruses, Viroids and Prions

Explain why HIV becomes resistant so quickly when a single drug is used therapeutically.

The term "segmented" refers to viruses that

For which of the following processes are enzymes not required?

After growth in tissue culture, the infected cells lyse and the virus may be harvested from

Why are viroids resistant to nucleases?

Plant viruses may be transmitted by

Animal viruses are divided into a number of families whose names end in

Electron microscopy is useful for counting viruses and distinguishing between infective and non-infective virions.

Viruses that infect bacteria are referred to as

Which does not refer to the shape of a virus?

If reasonably pure preparations of virus are available, the number of virus present may be determined by

Naked and enveloped viruses both may enter the host via endocytosis.

The best-known examples of viruses that cause latent infections are

The terms isometric, icosahedral and pleomorphic refer to

Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why?

Regarding phage replication,

Which of the following is not a characteristic of normal cells?

Carriers

Assembly of the T4 phage

The enveloped viruses typically obtain their envelope

Humans and the Microbial World

The Molecules of Life

Microscopy and Cell Structure

Dynamics of Prokaryotic Growth

Control of Microbial Growth

Metabolism: Fueling Cell Growth

The Blueprint of Life, From Dna to Protein

Bacterial Genetics

Biotechnology and Recombinant Dna

Identification and Classification of Prokaryotes

The Diversity of Prokaryotic Organisms

The Eukaryotic Members of the Microbial World

The Innate Immune Response

The Adaptive Immune Response

Host-Microbe Interactions

Immunologic Disorders

Applications of Immune Responses

Epidemiology

Antimicrobial Medications

Respiratory System Infections

Skin Infections

Wound Infections

Digestive System Infections

Genitourinary Infections

Nervous System Infections

Blood and Lymphatic Infections

Hiv Disease and Complications of Immunodeficiency

Microbial Ecology

Environmental Microbiology: Treatment of Water, Wastes, and Polluted Habitats

Food Microbiology

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