Question 1

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. B

Question 2

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 correcting errors in genome replication. 
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 correcting errors in genome replication. 
C) RNA viruses replicate faster. 
D) RNA viruses can incorporate a variety of nonstandard bases. B

Question 3

-Which of the three types of viruses shown in the figure above would you expect to include a capsid(s)as part of their overall structure?

Accepted Answer

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

Question 4

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 5

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV).The cell contents are left in a covered test tube overnight.The next day this mixture is sprayed on tobacco plants.Which of the following would be expected to occur?

Accepted Answer

A) The plants would develop some but not all of the symptoms of the TMV infection. 
B) The plants would develop symptoms typically produced by viroids. 
C) The plants would develop the typical symptoms of TMV infection. 
D) The plants would not show any disease symptoms. 
A) The plants would develop some but not all of the symptoms of the TMV infection. 
B) The plants would develop symptoms typically produced by viroids. 
C) The plants would develop the typical symptoms of TMV infection. 
D) The plants would not show any disease symptoms.

Question 6

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 order to be able to remain latent in an infected live cell,HSV must be able to shut down what process?

Accepted Answer

A) DNA replication 
B) transcription of viral genes 
C) apoptosis of a virally infected cell 
D) all immune responses 
A) DNA replication 
B) transcription of viral genes 
C) apoptosis of a virally infected cell 
D) all immune responses

Question 7

-In the figure above,at the arrow marked II,what enzyme is being utilized?

Accepted Answer

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

Question 8

-In the figure above,when new viruses are being assembled during the step labeled IV,how is the assembly of the new virus particles completed?

Accepted Answer

A) by host cell chaperones 
B) by assembly proteins coded for by the host nucleus 
C) by assembly proteins coded for by the viral genes 
D) the proteins self-assemble 
A) by host cell chaperones 
B) by assembly proteins coded for by the host nucleus 
C) by assembly proteins coded for by the viral genes 
D) the proteins self-assemble

Question 9

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

Accepted Answer

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

Question 10

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 11

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 12

Most molecular biologists think that viruses originated from naked bits 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) 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) Viral genomes are usually similar to the genome of the host cell.

Question 13

Which of the following series of events best reflects what we know about how the flu virus moves between species?

Accepted Answer

A) An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans. 
B) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. 
C) A flu virus from a human epidemic or pandemic infects birds;the birds replicate the virus differently and then pass it back to humans. 
D) An animal such as a pig is infected with more than one virus,genetic recombination occurs,the new virus mutates and is passed to a new species such as a bird,and the virus mutates and can be transmitted to humans. 
A) An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans. 
B) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. 
C) A flu virus from a human epidemic or pandemic infects birds;the birds replicate the virus differently and then pass it back to humans. 
D) An animal such as a pig is infected with more than one virus,genetic recombination occurs,the new virus mutates and is passed to a new species such as a bird,and the virus mutates and can be transmitted to humans.

Question 14

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 15

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 16

Which of the following statements correctly describes one difference between vertical and horizontal transmission of plant viruses?

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. 
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.

Question 17

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 statements best describes 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 it is injected like the genome of a phage. 
D) The viral envelope mediates entry into the cell,the capsid docks onto the nuclear membrane,and the genome is all that enters the nucleus. 
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 it is injected like the genome of a phage. 
D) The viral envelope mediates entry into the cell,the capsid docks onto the nuclear membrane,and the genome is all that enters the nucleus.

Question 18

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 19

Which of the following statements correctly describes one characteristic of the lytic cycle of viral replication?

Accepted Answer

A) Many bacterial cells containing viral DNA are produced. 
B) Viral DNA is incorporated into the host genome. 
C) The viral genome replicates without destroying the host. 
D) A large number of phages are released at a time. 
A) Many bacterial cells containing viral DNA are produced. 
B) Viral DNA is incorporated into the host genome. 
C) The viral genome replicates without destroying the host. 
D) A large number of phages are released at a time.

Question 20

Which of the following statements correctly describes viruses?

Accepted Answer

A) They cannot reproduce without a host cell. 
B) They can reproduce by dividing. 
C) They can carry out their own metabolic activities. 
D) They have a genome similar to prokaryotic and eukaryotic cells. 
A) They cannot reproduce without a host cell. 
B) They can reproduce by dividing. 
C) They can carry out their own metabolic activities. 
D) They have a genome similar to prokaryotic and eukaryotic cells.

Exam 17: Viruses

RNA viruses require their own supply of certain enzymes because

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

-Which of the three types of viruses shown in the figure above would you expect to include a capsid(s)as part of their overall structure?

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV).The cell contents are left in a covered test tube overnight.The next day this mixture is sprayed on tobacco plants.Which of the following would be expected to occur?

-In the figure above,at the arrow marked II,what enzyme is being utilized?

-In the figure above,when new viruses are being assembled during the step labeled IV,how is the assembly of the new virus particles completed?

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

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

Emerging viruses arise by

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

Which of the following series of events best reflects what we know about how the flu virus moves between species?

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

What is the function of reverse transcriptase in retroviruses?

Which of the following statements correctly describes one difference between vertical and horizontal transmission of plant viruses?

A human pandemic is

Which of the following statements correctly describes one characteristic of the lytic cycle of viral replication?

Which of the following statements correctly describes viruses?

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

Ecological Communities

Ecosystems and Energy

Conservation Biology and Global Change

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