Question 1

What is the function of reverse transcriptase in retroviruses?

Accepted Answer

A)  It hydrolyzes the host cell's DNA. 
B)  It uses viral RNA as a template for DNA synthesis. 
C)  It converts host cell RNA into viral DNA. 
D)  It uses viral RNA as a template for making complementary RNA strands. 
A)  It hydrolyzes the host cell's DNA. 
B)  It uses viral RNA as a template for DNA synthesis. 
C)  It converts host cell RNA into viral DNA. 
D)  It uses viral RNA as a template for making complementary RNA strands.

Question 2

Viral envelopes can best be analyzed with which of the following techniques?

Accepted Answer

A)  antibodies against specific proteins not found in the host membranes 
B)  DNA staining and visualization with the light microscope 
C)  use of plaque assays for quantitative measurement of viral titer 
D)  immunofluorescent tagging of capsid proteins 
A)  antibodies against specific proteins not found in the host membranes 
B)  DNA staining and visualization with the light microscope 
C)  use of plaque assays for quantitative measurement of viral titer 
D)  immunofluorescent tagging of capsid proteins

Question 3

Which of the following statements correctly describes the most probable fate of a newly emerging virus that causes high mortality in its host?

Accepted Answer

A)  It is able to spread to a large number of new hosts quickly because the new hosts have no immunological memory of them. 
B)  The new virus replicates quickly and undergoes rapid adaptation to a series of divergent hosts. 
C)  Sporadic outbreaks will be followed almost immediately by a widespread pandemic. 
D)  The newly emerging virus will die out rather quickly or will mutate to be far less lethal. 
A)  It is able to spread to a large number of new hosts quickly because the new hosts have no immunological memory of them. 
B)  The new virus replicates quickly and undergoes rapid adaptation to a series of divergent hosts. 
C)  Sporadic outbreaks will be followed almost immediately by a widespread pandemic. 
D)  The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

Question 4

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

Accepted Answer

A)  metabolism 
B)  ribosomes 
C)  genetic material composed of nucleic acid 
D)  cell division 
A)  metabolism 
B)  ribosomes 
C)  genetic material composed of nucleic acid 
D)  cell division

Question 5

RNA viruses require their own supply of certain enzymes because

Accepted Answer

A)  host cells rapidly destroy the viruses. 
B)  host cells lack enzymes that can replicate the viral genome. 
C)  these enzymes translate viral mRNA into proteins. 
D)  these enzymes penetrate host cell membranes. 
A)  host cells rapidly destroy the viruses. 
B)  host cells lack enzymes that can replicate the viral genome. 
C)  these enzymes translate viral mRNA into proteins. 
D)  these enzymes penetrate host cell membranes.

Question 6

Which of the following statements correctly describes the lysogenic cycle of lambda (λ) phage?

Accepted Answer

A)  After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses. 
B)  Most of the prophage genes are activated by the product of a particular prophage gene. 
C)  The phage genome replicates along with the host genome. 
D)  Certain environmental triggers can cause the phage to exit the host genome, switching from the lytic to the lysogenic. 
A)  After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses. 
B)  Most of the prophage genes are activated by the product of a particular prophage gene. 
C)  The phage genome replicates along with the host genome. 
D)  Certain environmental triggers can cause the phage to exit the host genome, switching from the lytic to the lysogenic.

Question 7

Why do RNA viruses tend to have unusually high rates of mutation?

Accepted Answer

A)  RNA nucleotides are more unstable than DNA nucleotides. 
B)  Replication of their genomes does not involve proofreading. 
C)  RNA viruses replicate faster. 
D)  RNA viruses can incorporate a variety of nonstandard bases. 
A)  RNA nucleotides are more unstable than DNA nucleotides. 
B)  Replication of their genomes does not involve proofreading. 
C)  RNA viruses replicate faster. 
D)  RNA viruses can incorporate a variety of nonstandard bases.

Question 8

Figure 17.2
-In Figure 17.2, at the arrow marked II, what enzyme(s) is (are) being utilized?

Accepted Answer

A)  reverse transcriptase 
B)  viral DNA polymerase 
C)  host cell DNA polymerase 
D)  host cell RNA polymerase 
E)  host cell DNA and RNA polymerases 
A)  reverse transcriptase 
B)  viral DNA polymerase 
C)  host cell DNA polymerase 
D)  host cell RNA polymerase 
E)  host cell DNA and RNA polymerases

Question 9

Please use the following information to answer the question(s) below.
The herpesviruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex virus (HSV) types I and II, causing facial and genital lesions, and the varicella zoster virus (VSV), causing chicken pox and shingles. Each of these three actively infects nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others.
-If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection?

Accepted Answer

A)  vaccination of all persons with preexisting cases 
B)  interference with new viral replication in preexisting cases 
C)  treatment of the HSV lesions to shorten the breakout 
D)  medication that destroys surface HSV before it gets to neurons 
A)  vaccination of all persons with preexisting cases 
B)  interference with new viral replication in preexisting cases 
C)  treatment of the HSV lesions to shorten the breakout 
D)  medication that destroys surface HSV before it gets to neurons

Question 10

A human pandemic is

Accepted Answer

A)  a viral disease that infects all humans. 
B)  a flu that kills more than 1 million people. 
C)  an epidemic that extends around the world. 
D)  a virus that increases in mortality rate as it spreads. 
A)  a viral disease that infects all humans. 
B)  a flu that kills more than 1 million people. 
C)  an epidemic that extends around the world. 
D)  a virus that increases in mortality rate as it spreads.

Question 11

Please use the following information to answer the question(s) below.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. Table 17.1 shows the results of testing five viruses (A-E) for nuclease sensitivity , the ability of the viral genome to act as an mRNA, and the presence (+) or absence (-) of each virus's own polymerase.   Table 17.1
-Based on Table 17.1, which virus meets the Baltimore requirements for a retrovirus?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 12

Emerging viruses arise by

Accepted Answer

A)  mutation of existing viruses. 
B)  the spread of existing viruses to new host species. 
C)  the spread of existing viruses more widely within their host species. 
D)  all of the above 
A)  mutation of existing viruses. 
B)  the spread of existing viruses to new host species. 
C)  the spread of existing viruses more widely within their host species. 
D)  all of the above

Question 13

Which of the following characteristics determine a virus's host range?

Accepted Answer

A)  the enzymes carried by the virus 
B)  whether its nucleic acid is DNA or RNA 
C)  the proteins in the host's cytoplasm 
D)  the proteins on its surface and that of the host 
A)  the enzymes carried by the virus 
B)  whether its nucleic acid is DNA or RNA 
C)  the proteins in the host's cytoplasm 
D)  the proteins on its surface and that of the host

Question 14

Refer to the treatments listed below to answer the following question(s).
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent.
I. Treat the substance with nucleases that destroy all nucleic acids and then determine whether it is still infectious.
II. Filter the substance to remove all elements smaller than what can be easily seen under a light microscope.
III. Culture the substance by itself on nutritive medium, away from any plant cells.
IV. Treat the sample with proteases that digest all proteins and then determine whether it is still infectious.
-If you already knew that the infectious agent was a prion, which treatment would allow you to distinguish this?

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  IV only 
E)  either I or IV 
A)  I only 
B)  II only 
C)  III only 
D)  IV only 
E)  either I or IV

Question 15

Which of the following statements accurately describes plant virus infections?

Accepted Answer

A)  They can be controlled by the use of antibiotics. 
B)  They are spread via the plasmodesmata. 
C)  They have little effect on plant growth. 
D)  They are rarely spread by insects. 
A)  They can be controlled by the use of antibiotics. 
B)  They are spread via the plasmodesmata. 
C)  They have little effect on plant growth. 
D)  They are rarely spread by insects.

Exam 17: Viruses

What is the function of reverse transcriptase in retroviruses?

Viral envelopes can best be analyzed with which of the following techniques?

Which of the following statements correctly describes the most probable fate of a newly emerging virus that causes high mortality in its host?

Which of the following characteristics, structures, or processes is common to both bacteria and viruses?

RNA viruses require their own supply of certain enzymes because

Which of the following statements correctly describes the lysogenic cycle of lambda (λ) phage?

Why do RNA viruses tend to have unusually high rates of mutation?

Figure 17.2 -In Figure 17.2, at the arrow marked II, what enzyme(s) is (are) being utilized?

A human pandemic is

Emerging viruses arise by

Which of the following characteristics determine a virus's host range?

Which of the following statements accurately describes plant virus infections?

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

Membrane Transport and Cell Signaling

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Development, Stem Cells, and Cancer

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

Early Life and the Diversification of Prokaryotes

The Origin and Diversification of Eukaryotes

The Colonization of Land by Plants and Fungi

The Rise of Animal Diversity

Plant Structure and Growth

Resource Acquisition, Nutrition, and Transport in Vascular Plants

Reproduction and Domestication of Flowering Plants

Plant Responses to Internal and External Signals

Homeostasis and Endocrine Signaling

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Reproduction and Development

Neurons, Synapses, and Signaling

Nervous and Sensory Systems

Motor Mechanisms and Behavior

Population Ecology and the Distribution of Organisms

Species Interactions

Ecosystems and Energy

Global Ecology and Conservation Biology

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