Question 1

What are prions?

Accepted Answer

A) mobile segments of DNA 
B) tiny molecules of RNA that infect plants 
C) viral DNA that has had to attach itself to the host genome 
D) misfolded versions of normal brain protein 
E) viruses that invade bacteria 
A) mobile segments of DNA 
B) tiny molecules of RNA that infect plants 
C) viral DNA that has had to attach itself to the host genome 
D) misfolded versions of normal brain protein 
E) viruses that invade bacteria

Question 2

Which of the following is characteristic of the lytic cycle?

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. 
E) The virus-host relationship usually lasts for generations. 
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. 
E) The virus-host relationship usually lasts for generations.

Question 3

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 bacterial or viral, which treatment would allow you to distinguish between these two possibilities?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) either II or IV 
A) I 
B) II 
C) III 
D) IV 
E) either II or IV

Question 4

Use the following information to answer the following questions.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA.
The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase.
  
-Based on the above table, which virus meets the requirements for a bacteriophage?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) E 
A) A 
B) B 
C) C 
D) D 
E) E

Question 5

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 upper leaves to 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 upper leaves to 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 6

Which of the following series 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 influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. 
E) 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, 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 influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. 
E) 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, the virus mutates and can be transmitted to humans.

Question 7

Use the following information to answer the questions below.
Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6300 nucleotides. Its virion is 25-30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets.
-If this virus has a positive RNA strand as its genome, it begins the infection by using this strand as mRNA. Therefore, which of the following do you expect to be able to measure?

Accepted Answer

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

Question 8

Use the following figure to answer the questions below.
  
-In the figure, 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 9

Use the following information to answer the few questions.
The herpes viruses 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 (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect 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 
E) interaction with histones 
A) DNA replication 
B) transcription of viral genes 
C) apoptosis of a virally infected cell 
D) all immune responses 
E) interaction with histones

Question 10

Use the following information to answer the questions below.
Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6300 nucleotides. Its virion is 25-30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets.
-How many nucleotides of the genome would you expect to find in one capsid?

Accepted Answer

A) 1 
B) ~6 
C) ~20 
D) ~180 
E) ~6300 
A) 1 
B) ~6 
C) ~20 
D) ~180 
E) ~6300

Question 11

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
-Which treatment could definitively determine whether or not the component is a viroid?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) first II and then III 
A) I 
B) II 
C) III 
D) IV 
E) first II and then III

Question 12

Use the following information to answer the following questions.
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA.
The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase.
  
-Based on the above table, which virus meets the Baltimore requirements for a retrovirus?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) E 
A) A 
B) B 
C) C 
D) D 
E) E

Question 13

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 translates viral RNA into proteins. 
E) 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 translates viral RNA into proteins. 
E) It uses viral RNA as a template for making complementary RNA strands.

Exam 19: Viruses

What are prions?

Which of the following is characteristic of the lytic cycle?

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

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

Use the following figure to answer the questions below. -In the figure, at the arrow marked II, what enzyme(s)are being utilized?

What is the function of reverse transcriptase in retroviruses?

Introduction: Evolution and Themes of Biology

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

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

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

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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