Question 1

Which of the following statements correctly describes a difference between viruses and prions?

Accepted Answer

A)  Viruses infect many types of cells, whereas prions infect only prokaryotic cells. 
B)  Viruses have capsids composed of protein, whereas prions are made only of nucleic acid. 
C)  Viruses have genomes composed of RNA, whereas prions have genomes composed of DNA. 
D)  Viruses generally cause disease symptoms quickly, whereas prions generally take many years to cause disease symptoms. 
A)  Viruses infect many types of cells, whereas prions infect only prokaryotic cells. 
B)  Viruses have capsids composed of protein, whereas prions are made only of nucleic acid. 
C)  Viruses have genomes composed of RNA, whereas prions have genomes composed of DNA. 
D)  Viruses generally cause disease symptoms quickly, whereas prions generally take many years to cause disease symptoms.

Question 2

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 3

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

Accepted Answer

A)  T2 protein and T4 DNA. 
B)  T4 protein and T2 DNA. 
C)  T2 protein and T2 DNA. 
D)  T4 protein and T4 DNA. 
A)  T2 protein and T4 DNA. 
B)  T4 protein and T2 DNA. 
C)  T2 protein and T2 DNA. 
D)  T4 protein and T4 DNA.

Question 4

-Which of the three types of viruses shown in the figure would you expect to include a capsid(s)?

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  I, II, and III 
A)  I only 
B)  II only 
C)  III only 
D)  I, II, and III

Question 5

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

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 6

What is the difference between an epidemic and a pandemic?

Accepted Answer

A)  An epidemic is a disease; a pandemic is a treatment. 
B)  An epidemic is restricted to a local region; a pandemic is global. 
C)  An epidemic has low mortality; a pandemic has higher mortality. 
D)  An epidemic is caused by a bacterial infection; a pandemic is caused by a viral infection. 
A)  An epidemic is a disease; a pandemic is a treatment. 
B)  An epidemic is restricted to a local region; a pandemic is global. 
C)  An epidemic has low mortality; a pandemic has higher mortality. 
D)  An epidemic is caused by a bacterial infection; a pandemic is caused by a viral infection.

Question 7

Which of the following processes can viruses carry out?

Accepted Answer

A)  They can manufacture their own ATP, proteins, and nucleic acids. 
B)  They can use the host cell to copy themselves and make viral proteins. 
C)  They can use the host cell to copy themselves and then synthesise their own proteins inside the viral capsid. 
D)  They can metabolise food and produce their own ATP. 
A)  They can manufacture their own ATP, proteins, and nucleic acids. 
B)  They can use the host cell to copy themselves and make viral proteins. 
C)  They can use the host cell to copy themselves and then synthesise their own proteins inside the viral capsid. 
D)  They can metabolise food and produce their own ATP.

Question 8

A virus consisting of a single strand of RNA, which is reverse transcribed into complementary DNA, is referred to as a ________.

Accepted Answer

A)  protease 
B)  retrovirus 
C)  bacteriophage 
D)  non-enveloped virus 
A)  protease 
B)  retrovirus 
C)  bacteriophage 
D)  non-enveloped virus

Question 9

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 millilitre of culture was determined.
-Using the data in the figure, 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 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 11

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 can incorporate a variety of nonstandard bases. 
D)  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 can incorporate a variety of nonstandard bases. 
D)  RNA viruses are more sensitive to mutagens.

Question 12

The herpesviruses are important enveloped DNA viruses that cause disease in vertebrates and in some invertebrates such as oysters. Some of the human forms 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 later reactivate, replicate again, and infect 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 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 mediates entry into 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 is injected like the genome of a phage. 
D)  The viral envelope mediates entry into the cell, the capsid mediates entry into the nuclear membrane, and the genome is all that enters the nucleus.

Question 13

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 14

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 15

Some viruses can be crystallised and their structures analysed. 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 begins its infection of a cell by using its genome as mRNA, which of the following would you expect to be able to measure when analysing the reproduction of this virus?

Accepted Answer

A)  replication rate 
B)  transcription rate 
C)  translation rate 
D)  formation of new transcription factors 
A)  replication rate 
B)  transcription rate 
C)  translation rate 
D)  formation of new transcription factors

Question 16

The virus genome and viral proteins are assembled into virus particles during which of the following parts of the reproductive cycle?

Accepted Answer

A)  the lytic cycle and the lysogenic cycle in all known host organisms 
B)  the lysogenic cycle only 
C)  the lytic cycle only 
D)  the lytic cycle in all host organisms but the lysogenic cycle only in bacteria 
A)  the lytic cycle and the lysogenic cycle in all known host organisms 
B)  the lysogenic cycle only 
C)  the lytic cycle only 
D)  the lytic cycle in all host organisms but the lysogenic cycle only in bacteria

Question 17

Which of the following statements supports the argument that viruses are nonliving?

Accepted Answer

A)  They do not carry out metabolic processes. 
B)  Their DNA does not encode proteins. 
C)  They have RNA rather than DNA. 
D)  They do not evolve. 
A)  They do not carry out metabolic processes. 
B)  Their DNA does not encode proteins. 
C)  They have RNA rather than DNA. 
D)  They do not evolve.

Question 18

Which of the following statements accurately 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 is integrated in the host chromosome where it is replicated along with the host genome. 
D)  The phage DNA is copied and exits the cell as a phage. 
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 is integrated in the host chromosome where it is replicated along with the host genome. 
D)  The phage DNA is copied and exits the cell as a phage.

Question 19

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. What would you expect to happen to the plants that were sprayed with the mixture?

Accepted Answer

A)  The plants would develop some but not all of the symptoms of the TMV infection. 
B)  The plants would develop the typical symptoms of TMV infection. 
C)  The plants would not show any disease symptoms. 
D)  The plants would become infected, but extracts from these plants would be unable to infect other plants. 
A)  The plants would develop some but not all of the symptoms of the TMV infection. 
B)  The plants would develop the typical symptoms of TMV infection. 
C)  The plants would not show any disease symptoms. 
D)  The plants would become infected, but extracts from these plants would be unable to infect other plants.

Question 20

HIV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What are the practical consequences of these findings?

Accepted Answer

A)  HIV can be transmitted more easily from person to person than the flu virus. 
B)  The flu virus can be transmitted more easily from person-to-person than HIV. 
C)  This property of HIV makes it more likely to be a pandemic than the flu virus. 
D)  Disinfecting surfaces is more important to reduce the spread of HIV than the flu. 
A)  HIV can be transmitted more easily from person to person than the flu virus. 
B)  The flu virus can be transmitted more easily from person-to-person than HIV. 
C)  This property of HIV makes it more likely to be a pandemic than the flu virus. 
D)  Disinfecting surfaces is more important to reduce the spread of HIV than the flu.

Exam 19: Viruses

Which of the following statements correctly describes a difference between viruses and prions?

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

-Which of the three types of viruses shown in the figure would you expect to include a capsid(s)?

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

What is the difference between an epidemic and a pandemic?

Which of the following processes can viruses carry out?

A virus consisting of a single strand of RNA, which is reverse transcribed into complementary DNA, is referred to as a ________.

Why do scientists consider HIV to be an 'emerging virus'?

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

What is the function of reverse transcriptase in retroviruses?

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

The virus genome and viral proteins are assembled into virus particles during which of the following parts of the reproductive cycle?

Which of the following statements supports the argument that viruses are nonliving?

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

HIV is inactivated in the laboratory after a few minutes of sitting at room temperature, but the flu virus is still active after sitting for several hours. What are the practical consequences of these findings?

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 Colonised 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 Signalling

Nervous Systems

Sensory and Motor Mechanisms

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