Question 1

If you were trying to create an attenuated virus in order to develop a vaccine,which of the following strategies might you use?

Accepted Answer

A) Isolate the virus and inject it directly into a person. 
B) Isolate the virus,destroy it with UV light,and inject it into a person. 
C) Isolate the virus,expose it to a culture of bovine cells for several generations,and inject the live virus into a person. 
D) Use mechanical forces to break the virus into smaller pieces,then inject these pieces into a person. 
A) Isolate the virus and inject it directly into a person. 
B) Isolate the virus,destroy it with UV light,and inject it into a person. 
C) Isolate the virus,expose it to a culture of bovine cells for several generations,and inject the live virus into a person. 
D) Use mechanical forces to break the virus into smaller pieces,then inject these pieces into a person.

Question 2

Which of the following is a reason why viruses are considered non-living?

Accepted Answer

A) They contain different nucleotides in their DNA and RNA. 
B) They are surrounded by polysaccharides. 
C) They do not have ribosomes or tRNAs. 
D) They do not contain a nuclear membrane. 
A) They contain different nucleotides in their DNA and RNA. 
B) They are surrounded by polysaccharides. 
C) They do not have ribosomes or tRNAs. 
D) They do not contain a nuclear membrane.

Question 3

You have isolated the genome from a novel virus and would like to determine its composition.You have three tubes,each containing one of these substances: 1. a protein that degrades dsDNA (DNase,tube 1)
2) a protein that degrades ssRNA (RNase,tube 2)
3) a protein that degrades other proteins (protease,tube 3)
You add some of your novel genome to tubes 1,2,and 3.The genome is not degraded in tube 1,2,or 3.Based on your knowledge of genome types that have been found in viruses,what could the genome's composition be?

Accepted Answer

A) dsRNA 
B) dsDNA that is resistant to DNase 
C) ssDNA 
D) It could be any of the above. 
A) dsRNA 
B) dsDNA that is resistant to DNase 
C) ssDNA 
D) It could be any of the above.

Question 4

Which receptors for HIV would you expect to find on macrophages and T cells?

Accepted Answer

A) CCR5 and CD4 on macrophages;CXCR4 and CD4 on T cells 
B) CCR5 and CXCR4 on macrophages;CD4 and CXCR4 on T cells 
C) CD4 and CXCR4 on macrophages;CXCR4 and CD4 on T cells 
D) CXCR4 and CD4 on macrophages;CCR5 and CD4 on T cells 
A) CCR5 and CD4 on macrophages;CXCR4 and CD4 on T cells 
B) CCR5 and CXCR4 on macrophages;CD4 and CXCR4 on T cells 
C) CD4 and CXCR4 on macrophages;CXCR4 and CD4 on T cells 
D) CXCR4 and CD4 on macrophages;CCR5 and CD4 on T cells

Question 5

What is the main structural difference between enveloped and nonenveloped viruses?

Accepted Answer

A) Enveloped viruses have their genetic material enclosed by a protein or phospholipid coat. 
B) Nonenveloped viruses have only a phospholipid membrane,while enveloped viruses have two membranes,the other one being a protein capsid. 
C) Enveloped viruses have a phospholipid membrane outside their capsid,whereas nonenveloped viruses do not. 
D) Both viruses have a capsid and phospholipid membrane,but,in the nonenveloped virus,the genetic material is between these two membranes,while in the enveloped virus the genetic material is inside both membranes. 
A) Enveloped viruses have their genetic material enclosed by a protein or phospholipid coat. 
B) Nonenveloped viruses have only a phospholipid membrane,while enveloped viruses have two membranes,the other one being a protein capsid. 
C) Enveloped viruses have a phospholipid membrane outside their capsid,whereas nonenveloped viruses do not. 
D) Both viruses have a capsid and phospholipid membrane,but,in the nonenveloped virus,the genetic material is between these two membranes,while in the enveloped virus the genetic material is inside both membranes.

Question 6

As obligate intracellular parasites,viruses have which of these characteristics?

Accepted Answer

A) After entering a cell,they manufacture their own ATP and carbon-containing compounds,like proteins and nucleic acids,in order to survive. 
B) After entering a cell,they use the host cell's machinery to make more copies of themselves using host proteins. 
C) After entering a cell,they use their own protein-synthesizing machinery to make more viral proteins that are used to assemble more copies of themselves. 
A) After entering a cell,they manufacture their own ATP and carbon-containing compounds,like proteins and nucleic acids,in order to survive. 
B) After entering a cell,they use the host cell's machinery to make more copies of themselves using host proteins. 
C) After entering a cell,they use their own protein-synthesizing machinery to make more viral proteins that are used to assemble more copies of themselves.

Question 7

You have isolated a newly discovered virus and are attempting to characterize it.You begin with its genome.You first isolate the virion-producing mRNA from culture cells infected with the virus.When you compare these mRNA with the viral genome,you find that they are complementary.What does this tell you?

Accepted Answer

A) This virus has a positive-sense genome. 
B) This virus has a negative-sense genome. 
C) This virus has an ambisense genome. 
D) The data are inconclusive. 
A) This virus has a positive-sense genome. 
B) This virus has a negative-sense genome. 
C) This virus has an ambisense genome. 
D) The data are inconclusive.

Question 8

You are a physician,and you suspect your patient has a viral infection that has never been seen in humans.The infection is localized in the cells along the lining of the small intestine.The cells in this area are regularly sloughed off and replaced with new cells;that is,these cells are constantly dividing.When you isolate this new virus and incubate it in culture,you discover that it does not replicate well in cultures that have slowly dividing cells,but it does much more damage in cultures that have actively dividing cells.What do these findings suggest about this new virus?

Accepted Answer

A) It is a double-stranded RNA virus. 
B) It is a negative-sense,single-stranded RNA virus. 
C) It is a double-stranded DNA virus. 
D) It is a single-stranded DNA virus. 
A) It is a double-stranded RNA virus. 
B) It is a negative-sense,single-stranded RNA virus. 
C) It is a double-stranded DNA virus. 
D) It is a single-stranded DNA virus.

Question 9

Figure 35.1  
-Using the data in Figure 35.1,how long does it take for virus B to go through one lytic cycle?

Accepted Answer

A) 15 minutes 
B) 30 minutes 
C) 45 minutes 
D) 60 minutes 
A) 15 minutes 
B) 30 minutes 
C) 45 minutes 
D) 60 minutes

Question 10

Why do scientists consider HIV to be an emerging virus?

Accepted Answer

A) HIV infected humans long before AIDS first become a problem in the early 1980s,but it has now mutated to a more deadly form. 
B) HIV mutates so rapidly that the virus of today has very little similarity to the virus in the first AIDS patients from the early 1980s. 
C) HIV used to infect only chimps,but it has mutated in such a way that it now infects humans. 
D) HIV is now starting to cause diseases other than AIDS,such as rare types of cancers and pneumonias. 
A) HIV infected humans long before AIDS first become a problem in the early 1980s,but it has now mutated to a more deadly form. 
B) HIV mutates so rapidly that the virus of today has very little similarity to the virus in the first AIDS patients from the early 1980s. 
C) HIV used to infect only chimps,but it has mutated in such a way that it now infects humans. 
D) HIV is now starting to cause diseases other than AIDS,such as rare types of cancers and pneumonias.

Question 11

It is believed that HIV has passed from chimps to humans more than once.This is very telling since it suggests that animal-to-human viral transmissions may be more common than previously thought.What is the best evidence in support of the conclusion that HIV made the chimp-to-human leap more than once?

Accepted Answer

A) HIV has multiple strains,and the virus does not appear to be able to leap from humans back to chimps. 
B) HIV has appeared on multiple continents. 
C) Human-to-human transmission of HIV requires direct personal contact that simply could not have resulted in the widespread outbreak we see today. 
D) Several species are known to have similar viruses resulting in immunodeficiency diseases. 
A) HIV has multiple strains,and the virus does not appear to be able to leap from humans back to chimps. 
B) HIV has appeared on multiple continents. 
C) Human-to-human transmission of HIV requires direct personal contact that simply could not have resulted in the widespread outbreak we see today. 
D) Several species are known to have similar viruses resulting in immunodeficiency diseases.

Question 12

Which of the following viruses would have a disrupted replication cycle if their reverse-transcriptase enzyme was non-functional?

Accepted Answer

A) Retroviruses 
B) Double-stranded DNA viruses 
C) Double-stranded RNA viruses 
D) Negative-sense single-stranded RNA viruses 
E) Positive-sense single-stranded RNA viruses 
A) Retroviruses 
B) Double-stranded DNA viruses 
C) Double-stranded RNA viruses 
D) Negative-sense single-stranded RNA viruses 
E) Positive-sense single-stranded RNA viruses

Question 13

Does treating a viral infection with antibiotics affect the course of the infection?

Accepted Answer

A) No;antibiotics do not kill viruses,because viruses use host proteins to replicate and antibiotics affect bacterial proteins. 
B) No;antibiotics do not kill viruses,because viruses self-assemble into active particles. 
C) Yes;antibiotics activate the immune system,and this decreases the severity of the infection. 
D) Yes;antibiotics can prevent viral entry into the cell by binding to host-receptor proteins. 
A) No;antibiotics do not kill viruses,because viruses use host proteins to replicate and antibiotics affect bacterial proteins. 
B) No;antibiotics do not kill viruses,because viruses self-assemble into active particles. 
C) Yes;antibiotics activate the immune system,and this decreases the severity of the infection. 
D) Yes;antibiotics can prevent viral entry into the cell by binding to host-receptor proteins.

Question 14

The HIV protease has been the target of several anti-HIV medications.This antiviral strategy is possible because

Accepted Answer

A) the HIV protease is easily precipitated out of the cell by combining with certain salt solutions. 
B) the HIV protease cleaves at specific places in viral polypeptides,which results in the formation of active viral proteins. 
C) these drugs are very specific to the active site of the HIV protease. 
D) both A and B apply. 
E) both B and C apply. 
A) the HIV protease is easily precipitated out of the cell by combining with certain salt solutions. 
B) the HIV protease cleaves at specific places in viral polypeptides,which results in the formation of active viral proteins. 
C) these drugs are very specific to the active site of the HIV protease. 
D) both A and B apply. 
E) both B and C apply.

Question 15

Figure 35.1  
-Cells were infected with approximately 1000 copies of either virus A or virus B at the 0 time point.At 5-minute intervals,a sample of the virus and cell mixture was removed.The intact cells were removed from the sample,and the number of viruses per milliliter of culture was determined.

Accepted Answer

A) 15 minutes 
B) 30 minutes 
C) 45 minutes 
D) 90 minutes 
A) 15 minutes 
B) 30 minutes 
C) 45 minutes 
D) 90 minutes

Exam 35: Viruses

If you were trying to create an attenuated virus in order to develop a vaccine,which of the following strategies might you use?

Which of the following is a reason why viruses are considered non-living?

Which receptors for HIV would you expect to find on macrophages and T cells?

What is the main structural difference between enveloped and nonenveloped viruses?

As obligate intracellular parasites,viruses have which of these characteristics?

Figure 35.1 -Using the data in Figure 35.1,how long does it take for virus B to go through one lytic cycle?

Why do scientists consider HIV to be an emerging virus?

Which of the following viruses would have a disrupted replication cycle if their reverse-transcriptase enzyme was non-functional?

Does treating a viral infection with antibiotics affect the course of the infection?

The HIV protease has been the target of several anti-HIV medications.This antiviral strategy is possible because

Figure 35.1 -Cells were infected with approximately 1000 copies of either virus A or virus B at the 0 time point.At 5-minute intervals,a sample of the virus and cell mixture was removed.The intact cells were removed from the sample,and the number of viruses per milliliter of culture was determined.

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Lipids, membranes, and the First Cells

Inside the Cell

Cell-Cell Interactions

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription, RNA Processing, and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

Analyzing and Engineering Genes

Genomics

Principles of Development

An Introduction to Animal Development

An Introduction to Plant Development

Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

Bacteria and Archaea

Protists

Green Algae and Land Plants

Fungi

An Introduction to Animals

Protostome Animals

Deuterostome Animals

Plant Form and Function

Water and Sugar Transport in Plants

Plant Nutrition

Plant Sensory Systems, signals, and Responses

Plant Reproduction

Animal Form and Function

Water and Electrolyte Balance in Animals

Animal Nutrition

Gas Exchange and Circulation

Electrical Signals in Animals

Animal Sensory Systems and Movement

Chemical Signals in Animals

Animal Reproduction

The Immune System in Animals

An Introduction to Ecology

Behavioural Ecology

Population Ecology

Community Ecology

Ecosystems

Biodiversity and Conservation Biology

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