Question 1

Why do scientists consider HIV to be an emerging virus?

Accepted Answer

A)  HIV infected humans long before the 1980s, but it has now mutated to a deadlier form. 
B)  HIV mutates rapidly, making the virus very different from HIV in the early 1980s. 
C)  HIV suddenly became apparent and widespread in the 1980s. 
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 the 1980s, but it has now mutated to a deadlier form. 
B)  HIV mutates rapidly, making the virus very different from HIV in the early 1980s. 
C)  HIV suddenly became apparent and widespread in the 1980s. 
D)  HIV is now starting to cause diseases other than AIDS, such as rare types of cancers and pneumonias.

Question 2

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 3

What is the function of reverse transcriptase in retroviruses?

Accepted Answer

A)  It uses viral RNA as a template for DNA synthesis. 
B)  It converts host cell RNA into viral DNA. 
C)  It translates viral RNA into proteins. 
D)  It uses viral RNA as a template for making complementary RNA strands. 
A)  It uses viral RNA as a template for DNA synthesis. 
B)  It converts host cell RNA into viral DNA. 
C)  It translates viral RNA into proteins. 
D)  It uses viral RNA as a template for making complementary RNA strands.

Question 4

Which of the following characteristics is typical of the lytic cycle of a bacteriophage?

Accepted Answer

A)  Viral DNA is incorporated into the host genome. 
B)  The viral genome replicates without destroying the host. 
C)  A large number of phages are released at a time. 
D)  The virus-host relationship usually lasts for generations. 
A)  Viral DNA is incorporated into the host genome. 
B)  The viral genome replicates without destroying the host. 
C)  A large number of phages are released at a time. 
D)  The virus-host relationship usually lasts for generations.

Question 5

Which of the following characteristics correctly describes retroviruses?

Accepted Answer

A)  They are made up of only a single protein. 
B)  They can only reproduce by infecting bacteria. 
C)  They have a single-stranded DNA that acts as a template for DNA synthesis. 
D)  They have a single-stranded RNA that acts as a template for DNA synthesis. 
A)  They are made up of only a single protein. 
B)  They can only reproduce by infecting bacteria. 
C)  They have a single-stranded DNA that acts as a template for DNA synthesis. 
D)  They have a single-stranded RNA that acts as a template for DNA synthesis.

Question 6

Use the following figure and information to answer the question(s) below.
 
Cells were infected with approximately 1,000 copies of either virus A or virus B at the 0 time point. At five-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.
Using the data in the figure, how long does it take for virus A to go through one lytic cycle?

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

Question 7

Refer to the treatments listed to answer the question.
You isolate an infectious substance 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 to analyze the substance and determine the nature of the infectious agent.
I.Treat the substance with enzymes that destroy all nucleic acids, and then determine whether the substance 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 on nutritive medium, away from any plant cells.
IV.Treat the sample with proteases that digest all proteins, and then determine whether the substance is still infectious.
If you already know that the infectious agent was either a virus or a prion, which method(s) listed above would allow you to distinguish between these two possibilities?

Accepted Answer

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

Question 8

Which of the following types of viral genomes could be transcribed using reverse transcriptase?

Accepted Answer

A)  ssRNA 
B)  dsRNA 
C)  ssDNA 
D)  dsDNA 
A)  ssRNA 
B)  dsRNA 
C)  ssDNA 
D)  dsDNA

Question 9

In 2009, a flu pandemic was believed to have originated when viral transmission occurred from pig to human, thereby earning the designation "swine flu." Although pigs are thought to have been the breeding ground for the 2009 virus, sequences from bird, pig, and human viruses were all found within this newly identified virus. What is the most likely explanation of why this virus contained sequences from bird, pig, and human viruses?

Accepted Answer

A)  The virus was descended from a common ancestor of bird, pig, and human flu viruses. 
B)  The infected individuals happened to be infected with all three virus types. 
C)  Related viruses can undergo genetic recombination if the RNA genomes mix and match during viral assembly. 
D)  The human was likely infected with various bacterial strains that contained all three RNA viruses. 
A)  The virus was descended from a common ancestor of bird, pig, and human flu viruses. 
B)  The infected individuals happened to be infected with all three virus types. 
C)  Related viruses can undergo genetic recombination if the RNA genomes mix and match during viral assembly. 
D)  The human was likely infected with various bacterial strains that contained all three RNA viruses.

Question 10

Which of the following statements correctly describes vaccines and how they help prevent viral infection?

Accepted Answer

A)  Vaccines are active versions of a virus that stimulate an immune reaction in a person. 
B)  Vaccines are inactive versions of a virus that stimulate an immune reaction in a person. 
C)  Vaccines are infectious proteins that stimulate an immune reaction in a person. 
D)  Vaccines are infectious enzymes that stimulate an immune reaction in a person. 
A)  Vaccines are active versions of a virus that stimulate an immune reaction in a person. 
B)  Vaccines are inactive versions of a virus that stimulate an immune reaction in a person. 
C)  Vaccines are infectious proteins that stimulate an immune reaction in a person. 
D)  Vaccines are infectious enzymes that stimulate an immune reaction in a person.

Question 11

A person is most likely to recover from a cold due to viral infection if the infected cells are able to perform which of the following processes?

Accepted Answer

A)  The cells can undergo normal cell division. 
B)  The cells can carry on translation, at least for a few hours. 
C)  The cells produce and release viral protein. 
D)  The cells transcribe viral mRNA. 
A)  The cells can undergo normal cell division. 
B)  The cells can carry on translation, at least for a few hours. 
C)  The cells produce and release viral protein. 
D)  The cells transcribe viral mRNA.

Question 12

Which of the following viruses would most likely have reverse transcriptase inside them?

Accepted Answer

A)  an RNA-based lytic virus 
B)  an RNA-based lysogenic virus 
C)  a DNA-based lytic virus 
D)  a DNA-based lysogenic virus 
A)  an RNA-based lytic virus 
B)  an RNA-based lysogenic virus 
C)  a DNA-based lytic virus 
D)  a DNA-based lysogenic virus

Question 13

Which of the following descriptions correctly identifies the main structural differences between viruses with envelopes and viruses without envelopes?

Accepted Answer

A)  Viruses with envelopes have their genetic material enclosed by a layer made only of protein. 
B)  Viruses without envelopes have only a phospholipid membrane, while viruses with envelopes have two membranes, the other one being a protein capsid. 
C)  Viruses with envelopes have a phospholipid membrane outside their capsid, whereas viruses without envelopes do not have a phospholipid membrane. 
D)  Both types of viruses have a capsid and phospholipid membrane; but in the viruses without envelopes, the genetic material is between these two membranes, while in the viruses with envelopes the genetic material is inside both membranes. 
A)  Viruses with envelopes have their genetic material enclosed by a layer made only of protein. 
B)  Viruses without envelopes have only a phospholipid membrane, while viruses with envelopes have two membranes, the other one being a protein capsid. 
C)  Viruses with envelopes have a phospholipid membrane outside their capsid, whereas viruses without envelopes do not have a phospholipid membrane. 
D)  Both types of viruses have a capsid and phospholipid membrane; but in the viruses without envelopes, the genetic material is between these two membranes, while in the viruses with envelopes the genetic material is inside both membranes.

Question 14

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

Accepted Answer

A)  The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. 
B)  A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. 
C)  An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. 
D)  An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans. 
A)  The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. 
B)  A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. 
C)  An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. 
D)  An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans.

Exam 19: Viruses

Why do scientists consider HIV to be an emerging virus?

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

What is the function of reverse transcriptase in retroviruses?

Which of the following characteristics is typical of the lytic cycle of a bacteriophage?

Which of the following characteristics correctly describes retroviruses?

Which of the following types of viral genomes could be transcribed using reverse transcriptase?

Which of the following statements correctly describes vaccines and how they help prevent viral infection?

A person is most likely to recover from a cold due to viral infection if the infected cells are able to perform which of the following processes?

Which of the following viruses would most likely have reverse transcriptase inside them?

Which of the following descriptions correctly identifies the main structural differences between viruses with envelopes and viruses without envelopes?

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

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

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

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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