Deck 6: Viruses

Question 1

Which filamentous virus causes a fatal disease in humans and is also related to primates?

A) HIV
B) Ebola
C) smallpox
D) cowpox
E) herpes virus

Answer 1

B

Question 2

Which infectious agent is identified by the nucleic acid genome being the entire infectious particle?

A) viruses
B) prions
C) viroids
D) virions
E) bacteria

Answer 2

C

Question 3

An icosahedral capsid is classified as having how many sides?

A) 4
B) 6
C) 8
D) 10
E) 20

Answer 3

E

Question 4

What type of diseases are unique in that they can be transmitted by an infective protein that propagates conformational change of existing molecules without synthesizing entirely new infective molecules?

A) viral
B) viroid
C) bacterial
D) virion
E) prion

Question 5

Which structure of a virion protects it from degradation and enables it to be transmitted outside the host?

A) capsule
B) capsid
C) envelope
D) nucleus
E) spikes

Question 6

What role do acute viruses play in their ecosystem?

A) transfer genes across species
B) act as predator or parasite
C) evolve symbiotically with host
D) act as a bioweapon
E) act as a viral shunt

Question 7

Which of the following is NOT one of the three forms a virus can assume?

A) prion
B) viral genome integrated within host DNA
C) intracellular replication complex
D) virion
E) virus particle

Question 8

In bacteriophage T4, the DNA genome is contained in the head, and binding to the host is facilitated by attachment of the

A) capsid.
B) neck.
C) tail fibers.
D) envelope.
E) tegument.

Question 9

Large asymmetrical viruses are distinguished in that they

A) have no envelope.
B) are protein fragments.
C) have few enzymes.
D) have nucleic acids.
E) have many enzymes.

Question 10

What can be counted as representing individual infectious virions from a phage suspension?

A) plaques
B) viruses
C) genomes
D) proteomes
E) burst size

Question 11

A polyhedron with 20 sides has identical ________ faces.

A) helical
B) filamentous
C) rectangular
D) triangular
E) asymmetrical

Question 12

Some viral species may derive their ________ from intracellular membranes, such as the nuclear membrane or endoplasmic reticulum.

A) capsid
B) genome
C) envelope
D) neck
E) tail fibers

Question 13

All of the following criteria are used to classify viruses according to the International Committee on Taxonomy of Viruses EXCEPT

A) genome composition.
B) size of the virus particle.
C) envelope.
D) capsid symmetry.
E) mutation rate.

Question 14

Which of the following is a term for the observable destruction of cells as a result of viral lysis?

A) tissue culture
B) lawn
C) soft agar
D) plaque
E) host

Question 15

Which of the following is INCORRECT about a virus?

A) It may cause human pneumonia.
B) It may be as large as some bacteria.
C) It conducts DNA repair.
D) It conducts protein folding by chaperones.
E) It is a cellular particle.

Question 16

Filamentous viruses are classified in part by the pattern of capsid monomers, which form a ________ tube around the genome.

A) icosahedral
B) filamentous
C) asymmetrical
D) complex
E) helical

Question 17

All of the following are true about the measles virus EXCEPT that it

A) is encased by an envelope of membrane.
B) fuses with the host cell membrane during infection.
C) has progeny that bud out of the host cell.
D) generates a rash of red spots on the skin of infected patients.
E) is never fatal.

Question 18

The RNA genome of the potato spindle tuber viroid requires which type of modified host polymerase for replication?

A) DNA-dependent DNA polymerase
B) DNA-dependent RNA polymerase
C) RNA-dependent DNA polymerase
D) RNA-dependent RNA polymerase
E) reverse transcriptase

Question 19

If something descended from a common ancestor, it is

A) monomeric.
B) monophyletic.
C) monogrammed.
D) monosyllabic.
E) monolithic.

Question 20

What phages have been used to nucleate the growth of crystalline "nanowires" for electronic devices?

A) icosahedral
B) complex
C) asymmetrical
D) filamentous
E) viroid

Question 21

David Baltimore proposed that the primary distinction among classes of viruses was the ________ composition and the route used to express messenger RNA.

A) genome
B) envelope
C) capsid
D) tegument
E) neck

Question 22

The genome of ________ ssRNA viruses can serve directly as mRNA.

A) positive-sense (+)
B) negative-sense (-)
C) all
D) double-stranded
E) prion

Question 23

A(n) ________ phage may integrate its genome into that of the host cell.

A) lytic
B) temperate
C) viroid
D) asymmetrical
E) oncogenic

Question 24

Which of the following steps is NOT part of the life cycle of a lytic phage?

A) Phage DNA is injected into the bacterial cell.
B) The phage DNA integrates into the bacterial chromosome.
C) Many copies of phage DNA are made.
D) The phage DNA is transcribed, and the resulting mRNA is translated to make capsid proteins.
E) All of the steps listed are part of the life cycle of a lytic phage.

Question 25

Proteomic analysis predicts seven major evolutionary categories of phage species with subgroups based on

A) type of genetic material.
B) virion structure.
C) shared hosts.
D) transcriptional strategy.
E) replicase gene sequence.

Question 26

Which of the following are genes of common ancestry in two genomes that share the same function?

A) homologs
B) open reading frames
C) proteomes
D) orthologs
E) lysogenic

Question 27

Which of the following is an example of double-stranded RNA viruses?

A) herpes viruses
B) corona viruses
C) retrovirus
D) orthomixoviruses
E) hepadnaviruses

Question 28

A key factor in the evolution of killer strains of influenza is that they

A) only have eight genes.
B) have an RNA genome.
C) contain reverse transcriptase.
D) have a segmented genome.
E) have a circular chromosome.

Question 29

Viruses may be classified by the ________ method.

A) Annapolis
B) Baltimore
C) Orono
D) Augusta
E) Portland

Question 30

What viruses are classified by using the suffix viridae?

A) genera
B) families
C) species
D) orders
E) classes

Question 31

CRISPR is a(n)

A) bacterial gene.
B) bacterial enzyme.
C) bacterial immune system.
D) inactive viral RNA.
E) cascade protein.

Question 32

The number of virus particles released at lysis is referred to as

A) the lytic number.
B) burst size.
C) the lysogenic number.
D) the temperate number.
E) the release number.

Question 33

So far, the known mechanisms of replication and mRNA expression define how many fundamental groups of virus species?

A) five
B) six
C) seven
D) eight
E) nine

Question 34

When a bacterial cell is infected, the virus protection coat

A) enters the host cell with the viral genome.
B) remains on the outside of the host cell.
C) enters the host cell separately from the viral genome.
D) is released to attach to and inject another host cell.
E) becomes part of the host cell membrane.

Question 35

The integrated phage genome is called a(n)

A) temperate.
B) lysogen.
C) oncogene.
D) lytic.
E) prophage.

Question 36

Dysbiosis is the result of

A) deterioration of health due to loss of bacteria.
B) increase in health due to loss of bacteria.
C) host bacterium undergoing a lytic cycle.
D) host bacterium undergoing a lysogenic cycle.
E) slow release.

Question 37

Which of the following is NOT true of the pararetroviruses?

A) They have an RNA genome.
B) They do not make a DNA intermediate.
C) Some have a viral reverse transcriptase.
D) Some use a host reverse transcriptase.
E) They consist of human and plant pathogens.

Question 38

Hershey & Chase (1952) showed that the transmission of DNA by a bacteriophage to a host cell led to the production of progeny bacteriophages. What did this confirm?

A) DNA is the hereditary material.
B) Viruses can infect bacteria.
C) Phage genomes can integrate into a bacterial genome.
D) Phages inject their genome through the cell envelope.
E) Various host molecules can serve as a phage receptor.

Question 39

The proteomic tree of bacteriophages is based on comprehensive analysis of viral

A) DNAs.
B) RNAs.
C) proteins.
D) capsids.
E) host ranges.

Question 40

Which structure remains outside, attached to the cell surface, after the genome is inserted?

A) an envelope
B) a neck
C) tail fibers
D) a ghost
E) temperate

Question 41

Some viruses require an RNA-dependent RNA polymerase. What does that mean? What would you call the host cell RNA polymerase (RNA pol)? What would you call reverse transcriptase (RTase)?

Question 42

Name the different types of receptors shown in the figure below.

Question 43

What happens when marine algae overgrows?

Question 44

Discuss the role that marine viruses play in carbon balance.

Question 45

Which virus is differentiated by being taken up by endocytosis?

A) hepatitis C
B) human immunodeficiency virus (HIV)
C) gonorrhea
D) syphilis
E) chlamydia

Question 46

What is NOT a difficulty of culturing viruses?

A) tropism for particular tissue
B) tissue culture may not show organ property
C) loss of virulence
D) able to observe a large population
E) need a double culture of host cell and viruses

Question 47

Tissue cultures are more feasible than whole animals for viral growth because they

A) can develop vaccines.
B) can test a multitude of chemical and antibiotic agents.
C) are more time-consuming.
D) are less expensive.
E) are more expensive.

Question 48

Within a host, receptor molecules can also determine the ________, or tendency to infect a particular tissue type.

A) tropism
B) host range
C) virulence
D) burst size
E) plaque

Question 49

In contrast to animal viruses and bacteriophages, plant viruses infect cells by mechanisms that do NOT involve specific

A) receptors.
B) membranes.
C) envelopes.
D) vectors.
E) hosts.

Question 50

What is the advantage of symmetry in viral particles?

Question 51

The proteins found in animals and plants that can recognize general signs of viral infections are

A) RNA interference.
B) interferons.
C) T-lymphocytes.
D) surface receptors.
E) antibodies.

Question 52

Which is the period of time that is categorized by virtually undetectable virions inside the infected cell?

A) eclipse
B) latent
C) rise
D) burst
E) lag

Question 53

Who was distinguished for modifying tissue culture procedure for plaque assays?

A) David Baltimore
B) Renato Dulbecco
C) Xinzheng Zhang
D) Paulo Verardi
E) Howard Temin

Question 54

Why are viruses not affected by antibiotics? Why are there so few antiviral drugs?

Question 55

Identify the outer structure shown in the figure below. What is it composed of and how does it differ from the bacterial version?

Question 56

What are prions and how do they cause disease?

Question 57

The primary factor determining the life cycle of an animal virus is the physical form of the

A) envelope.
B) capsid.
C) genome.
D) receptor.
E) burst.

Question 58

Why do many RNA viruses encode their own RNA-dependent RNA polymerase and package them in viral particles? How do we take advantage of these viral-specific polymerases?

Question 59

Compare and contrast the Baltimore classification of viruses to the proteomic analysis of bacteriophages. Which more accurately reflects the significant impact of phage evolution?

Question 60

Which of the following is FALSE concerning HIV?

A) It is the causative agent of AIDS.
B) It makes a DNA copy of its RNA genome.
C) Reverse transcriptase is translated from an early gene.
D) The virion contains two copies of the HIV genome.
E) The viral RNA is copied into double-stranded DNA.

Question 61

To count the number of viruses in a solution, one can perform a plaque assay. Describe how a plaque is generated in the case of a lytic virus and how a virus that does not lyse its host can be detected.

Question 62

How is the technique displayed in the figure below used to count virions in a solution?

Question 63

How can a virus be used to transfer genes from one bacterial cell to another?

Question 64

Evaluate what determines which cycle a temperate phage will go through as shown in the figure below.

Question 65

Why was the advent of tissue culture heralded as the end of the "monkey era"? What types of things are we able to do with it?

Question 66

During the eclipse period of a viral infection, why are the virions undetectable in the growth medium?

Question 67

What determines the host range and tropism of a virus?

Question 68

Define oncogenes and oncogenic viruses, and explain how they can be used in gene therapy.

Question 69

Explain the process shown in the figure below.

Question 70

What is it necessary for bacteriophage and animal virus entry into a cell? How does that differ from plant viral entry?