Question 1

The difference between vertical and horizontal transmission of plant viruses is that

Accepted Answer

A)  vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant. 
B)  vertical transmission is the spread of viruses from the upper leaves to the lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level. 
C)  vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size. 
D)  vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type. 
E)  vertical transmission is the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species. 
A)  vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant. 
B)  vertical transmission is the spread of viruses from the upper leaves to the lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level. 
C)  vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size. 
D)  vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type. 
E)  vertical transmission is the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species.

Question 2

Why do RNA viruses appear to have higher 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. 
E)  RNA viruses are more sensitive to mutagens. 
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. 
E)  RNA viruses are more sensitive to mutagens.

Question 3

Use the following information to answer the question below.
Some viruses can be crystallized and their structures analyzed. One such virus is yellow mottle virus, which infects beans. This virus has a single-stranded RNA genome containing about 6,300 nucleotides. Its capsid is 25-30 nm in diameter and contains 180 identical capsomeres.
-If the yellow mottle virus capsid has 20 facets, how many proteins form each facet?

Accepted Answer

A)  1 
B)  5 
C)  9 
D)  20 
E)  180 
A)  1 
B)  5 
C)  9 
D)  20 
E)  180

Question 4

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

Accepted Answer

A)  use of 15N to label specific nucleotides 
B)  antibodies against specific proteins not found in the host membranes 
C)  DNA staining and visualization with the light microscope 
D)  use of plaque assays for quantitative measurement of viral titer 
E)  immunofluorescent tagging of capsid proteins 
A)  use of 15N to label specific nucleotides 
B)  antibodies against specific proteins not found in the host membranes 
C)  DNA staining and visualization with the light microscope 
D)  use of plaque assays for quantitative measurement of viral titer 
E)  immunofluorescent tagging of capsid proteins

Question 5

Which of the following 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 seldom spread by insects. 
E)  They can never be passed vertically. 
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 seldom spread by insects. 
E)  They can never be passed vertically.

Question 6

Figure 17.2
-In Figure 17.2, when new viruses are being assembled (IV), what mediates the assembly?

Accepted Answer

A)  host cell chaperones 
B)  assembly proteins coded for by the host nucleus 
C)  assembly proteins coded for by the viral genes 
D)  viral RNA intermediates 
E)  nothing; they self-assemble 
A)  host cell chaperones 
B)  assembly proteins coded for by the host nucleus 
C)  assembly proteins coded for by the viral genes 
D)  viral RNA intermediates 
E)  nothing; they self-assemble

Question 7

Which of the following is the best predictor of how much damage a virus causes?

Accepted Answer

A)  ability of the infected cell to undergo normal cell division 
B)  ability of the infected cell to carry on translation 
C)  whether the infected cell produces viral protein 
D)  whether the viral mRNA can be transcribed 
E)  how much toxin the virus produces 
A)  ability of the infected cell to undergo normal cell division 
B)  ability of the infected cell to carry on translation 
C)  whether the infected cell produces viral protein 
D)  whether the viral mRNA can be transcribed 
E)  how much toxin the virus produces

Question 8

Figure 17.1
-Which of the three types of viruses shown in Figure 17.1 would you expect to include glycoproteins?

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  I and II only 
E)  all three 
A)  I only 
B)  II only 
C)  III only 
D)  I and II only 
E)  all three

Question 9

Which of the following statements 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. 
E)  The phage DNA is incorporated by crossing over into any nonspecific site on the host cell's DNA. 
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. 
E)  The phage DNA is incorporated by crossing over into any nonspecific site on the host cell's DNA.

Question 10

Refer to the treatments listed below to answer the following questions.
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, viroid, 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. treating the substance with nucleases that destroy all nucleic acids
and then determining whether it is still infectious
II. filtering the substance to remove all elements smaller than what can
be easily seen under a light microscope
III. culturing the substance by itself on nutritive medium, away from
any plant cells
IV. treating the sample with proteases that digest all proteins and then
determining whether it is still infectious
-If you already knew that the infectious agent was either a viroid or a prion, which treatment would allow you to distinguish between these two possibilities?

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 11

Use the following information to answer the few questions.
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 
E)  education about avoiding sources of infection 
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 
E)  education about avoiding sources of infection

Question 12

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

Accepted Answer

A)  Viruses contain either DNA or RNA. 
B)  Viruses are enclosed in protein capsids rather than plasma membranes. 
C)  Viruses can reproduce only inside host cells. 
D)  Viruses can infect both prokaryotic and eukaryotic cells. 
E)  Viral genomes are usually similar to the genome of the host cell. 
A)  Viruses contain either DNA or RNA. 
B)  Viruses are enclosed in protein capsids rather than plasma membranes. 
C)  Viruses can reproduce only inside host cells. 
D)  Viruses can infect both prokaryotic and eukaryotic cells. 
E)  Viral genomes are usually similar to the genome of the host cell.

Question 13

Figure 17.2
-In Figure 17.2, at the arrow marked II, what enzyme(s) 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 14

Use the following information to answer the few questions.
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.
-In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell-surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations?

Accepted Answer

A)  Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus. 
B)  The viral envelope is not required for infectivity, since the envelope does not enter the nucleus. 
C)  Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the genome of a phage. 
D)  The viral envelope mediates entry into the cell, the capsid enters into the nuclear membrane, and the genome is all that enters the nucleus. 
E)  The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate. 
A)  Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus. 
B)  The viral envelope is not required for infectivity, since the envelope does not enter the nucleus. 
C)  Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the genome of a phage. 
D)  The viral envelope mediates entry into the cell, the capsid enters into the nuclear membrane, and the genome is all that enters the nucleus. 
E)  The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate.

Question 15

Which viruses have single-stranded RNA that acts as a template for DNA synthesis?

Accepted Answer

A)  lytic phages 
B)  proviruses 
C)  viroids 
D)  bacteriophages 
E)  retroviruses 
A)  lytic phages 
B)  proviruses 
C)  viroids 
D)  bacteriophages 
E)  retroviruses

Exam 17: Viruses

The difference between vertical and horizontal transmission of plant viruses is that

Why do RNA viruses appear to have higher rates of mutation?

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

Which of the following describes plant virus infections?

Figure 17.2 -In Figure 17.2, when new viruses are being assembled (IV), what mediates the assembly?

Which of the following is the best predictor of how much damage a virus causes?

Figure 17.1 -Which of the three types of viruses shown in Figure 17.1 would you expect to include glycoproteins?

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

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory?

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

Which viruses have single-stranded RNA that acts as a template for DNA synthesis?

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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