Microbiology An Evolving Science 4E – Foster – TB

Microbiology An Evolving Science 4E – Foster – TB

CHAPTER 6: Viruses

MULTIPLE CHOICE

1. 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.

ANS: E DIF: Easy REF: 6.1 OBJ: 6.1a Define virus
MSC: Applying

2. Which of the following is a term for the observable destruction of cells as a result of viral lysis?
a. tissue culture d. plaque
b. lawn e. host
c. soft agar

ANS: D DIF: Easy REF: 6.1 OBJ: 6.1a Define virus
MSC: Understanding

3. What can be counted as representing individual infectious virions from a phage suspension?
a. plaques d. proteomes
b. viruses e. burst size
c. genomes

ANS: A DIF: Easy REF: 6.4
OBJ: 6.4b Recall examples of prophages or endogenous viruses contributing to host cell physiology
MSC: Analyzing

4. 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.

ANS: E DIF: Medium REF: 6.1 OBJ: 6.1a Define virus
MSC: Applying

5. 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

ANS: B DIF: Easy REF: 6.1
OBJ: 6.1c List the roles viruses play in ecosystems MSC: Applying

6. 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

ANS: A DIF: Easy REF: 6.1
OBJ: 6.1b Describe the three forms a virus can assume MSC: Applying

7. An icosahedral capsid is classified as having how many sides?
a. 4 d. 10
b. 6 e. 20
c. 8

ANS: E DIF: Easy REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Analyzing

8. A polyhedron with 20 sides has identical ________ faces.
a. helical d. triangular
b. filamentous e. asymmetrical
c. rectangular

ANS: D DIF: Easy REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Understanding

9. Which infectious agent is identified by the nucleic acid genome being the entire infectious particle?
a. viruses d. virions
b. prions e. bacteria
c. viroids

ANS: C DIF: Medium REF: 6.2
OBJ: 6.2c Contrast virions, viroids, and prions MSC: Analyzing

10. Some viral species may derive their ________ from intracellular membranes, such as the nuclear membrane or endoplasmic reticulum.
a. capsid d. neck
b. genome e. tail fibers
c. envelope

ANS: C DIF: Medium REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Remembering

11. Which structure of a virion protects it from degradation and enables it to be transmitted outside the host?
a. capsule d. nucleus
b. capsid e. spikes
c. envelope

ANS: B DIF: Easy REF: 6.2
OBJ: 6.2a State the functions of the structures that are present in all virions
MSC: Understanding

12. What phages have been used to nucleate the growth of crystalline “nanowires” for electronic devices?
a. icosahedral d. filamentous
b. complex e. viroid
c. asymmetrical

ANS: D DIF: Easy REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Applying

13. Filamentous viruses are classified in part by the pattern of capsid monomers, which form a ________ tube around the genome.
a. icosahedral d. complex
b. filamentous e. helical
c. asymmetrical

ANS: E DIF: Easy REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Analyzing

14. In bacteriophage T4, the DNA genome is contained in the head, and binding to the host is facilitated by attachment of the
a. capsid. d. envelope.
b. neck. e. tegument.
c. tail fibers.

ANS: C DIF: Easy REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Remembering

15. 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

ANS: D DIF: Medium REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Applying

16. Which filamentous virus causes a fatal disease in humans and is also related to primates?
a. HIV d. cowpox
b. Ebola e. herpes virus
c. smallpox

ANS: B DIF: Easy REF: 6.2
OBJ: 6.2b Identify ways virions can differ from each other MSC: Applying

17. 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 d. virion
b. viroid e. prion
c. bacterial

ANS: E DIF: Easy REF: 6.2
OBJ: 6.2c Contrast virions, viroids, and prions MSC: Understanding

18. Large asymmetrical viruses are distinguished in that they
a. have no envelope. d. have nucleic acids.
b. are protein fragments. e. have many enzymes.
c. have few enzymes.

ANS: E DIF: Medium REF: 6.3
OBJ: 6.3a Describe the diversity of viral genomes MSC: Analyzing

19. All of the following criteria are used to classify viruses according to the International Committee on Taxonomy of Viruses EXCEPT
a. genome composition. d. capsid symmetry.
b. size of the virus particle. e. mutation rate.
c. envelope.

ANS: E DIF: Medium REF: 6.3
OBJ: 6.3b List the criteria by which the International Committee on Taxonomy of Viruses (ICTV) classifies viruses MSC: Understanding

20. If something descended from a common ancestor, it is
a. monomeric. d. monosyllabic.
b. monophyletic. e. monolithic.
c. monogrammed.

ANS: B DIF: Medium REF: 6.3
OBJ: 6.3d Compare and contrast genome and proteome analysis for viral phylogeny construction
MSC: Understanding

21. Which of the following is an example of double-stranded RNA viruses?
a. herpes viruses d. orthomixoviruses
b. corona viruses e. hepadnaviruses
c. retrovirus

ANS: C DIF: Easy REF: 6.3
OBJ: 6.3c Categorize the genome composition and the route used to express messenger RNA (mRNA) in the Baltimore virus classification scheme MSC: Understanding

22. What viruses are classified by using the suffix viridae?
a. genera d. orders
b. families e. classes
c. species

ANS: B DIF: Medium REF: 6.3
OBJ: 6.3b List the criteria by which the International Committee on Taxonomy of Viruses (ICTV) classifies viruses MSC: Analyzing

23. Viruses may be classified by the ________ method.
a. Annapolis d. Augusta
b. Baltimore e. Portland
c. Orono

ANS: B DIF: Easy REF: 6.3
OBJ: 6.3c Categorize the genome composition and the route used to express messenger RNA (mRNA) in the Baltimore virus classification scheme MSC: Remembering

24. So far, the known mechanisms of replication and mRNA expression define how many fundamental groups of virus species?
a. five d. eight
b. six e. nine
c. seven

ANS: C DIF: Medium REF: 6.3
OBJ: 6.3c Categorize the genome composition and the route used to express messenger RNA (mRNA) in the Baltimore virus classification scheme MSC: Remembering

25. David Baltimore proposed that the primary distinction among classes of viruses was the ________ composition and the route used to express messenger RNA.
a. genome d. tegument
b. envelope e. neck
c. capsid

ANS: A DIF: Easy REF: 6.3
OBJ: 6.3c Categorize the genome composition and the route used to express messenger RNA (mRNA) in the Baltimore virus classification scheme MSC: Remembering

26. The genome of ________ ssRNA viruses can serve directly as mRNA.
a. positive-sense () d. double-stranded
b. negative-sense () e. prion
c. all

ANS: A DIF: Easy REF: 6.3
OBJ: 6.3a Describe the diversity of viral genomes MSC: Remembering

27. A key factor in the evolution of killer strains of influenza is that they
a. only have eight genes. d. have a segmented genome.
b. have an RNA genome. e. have a circular chromosome.
c. contain reverse transcriptase.

ANS: D DIF: Medium REF: 6.3
OBJ: 6.3c Categorize the genome composition and the route used to express messenger RNA (mRNA) in the Baltimore virus classification scheme MSC: Remembering

28. 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.

ANS: A DIF: Medium REF: 6.3
OBJ: 6.3c Categorize the genome composition and the route used to express messenger RNA (mRNA) in the Baltimore virus classification scheme MSC: Remembering

29. Which of the following are genes of common ancestry in two genomes that share the same function?
a. homologs d. orthologs
b. open reading frames e. lysogenic
c. proteomes

ANS: D DIF: Difficult REF: 6.3
OBJ: 6.3d Compare and contrast genome and proteome analysis for viral phylogeny construction
MSC: Remembering

30. The proteomic tree of bacteriophages is based on comprehensive analysis of viral
a. DNAs. d. capsids.
b. RNAs. e. host ranges.
c. proteins.

ANS: C DIF: Easy REF: 6.3
OBJ: 6.3d Compare and contrast genome and proteome analysis for viral phylogeny construction
MSC: Remembering

31. Proteomic analysis predicts seven major evolutionary categories of phage species with subgroups based on
a. type of genetic material. d. transcriptional strategy.
b. virion structure. e. replicase gene sequence.
c. shared hosts.

ANS: C DIF: Medium REF: 6.3
OBJ: 6.3d Compare and contrast genome and proteome analysis for viral phylogeny construction
MSC: Understanding

32. Which structure remains outside, attached to the cell surface, after the genome is inserted?
a. an envelope d. a ghost
b. a neck e. temperate
c. tail fibers

ANS: D DIF: Easy REF: 6.4
OBJ: 6.4a Distinguish the lytic, lysogenic, and slow-release viral cycles
MSC: Understanding

33. 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.

ANS: B DIF: Difficult REF: 6.4
OBJ: 6.4a Distinguish the lytic, lysogenic, and slow-release viral cycles
MSC: Applying

34. The number of virus particles released at lysis is referred to as
a. the lytic number. d. the temperate number.
b. burst size. e. the release number.
c. the lysogenic number.

ANS: B DIF: Easy REF: 6.4
OBJ: 6.4b Recall examples of prophages or endogenous viruses contributing to host cell physiology
MSC: Remembering

35. A(n) ________ phage may integrate its genome into that of the host cell.
a. lytic d. asymmetrical
b. temperate e. oncogenic
c. viroid

ANS: B DIF: Easy REF: 6.4
OBJ: 6.4a Distinguish the lytic, lysogenic, and slow-release viral cycles
MSC: Remembering

36. The integrated phage genome is called a(n)
a. temperate. d. lytic.
b. lysogen. e. prophage.
c. oncogene.

ANS: E DIF: Easy REF: 6.4
OBJ: 6.4b Recall examples of prophages or endogenous viruses contributing to host cell physiology
MSC: Remembering

37. CRISPR is a(n)
a. bacterial gene. d. inactive viral RNA.
b. bacterial enzyme. e. cascade protein.
c. bacterial immune system.

ANS: C DIF: Easy REF: 6.4
OBJ: 6.4c Explain how bacteria defend themselves against viruses
MSC: Remembering

38. 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.

ANS: B DIF: Easy REF: 6.4
OBJ: 6.4b Recall examples of prophages or endogenous viruses contributing to host cell physiology
MSC: Understanding

39. 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.

ANS: A DIF: Difficult REF: 6.4
OBJ: 6.4b Recall examples of prophages or endogenous viruses contributing to host cell physiology
MSC: Understanding

40. 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.

ANS: A DIF: Difficult REF: 6.4
OBJ: 6.4d Describe the impact of bacteriophages in the human intestinal tract
MSC: Understanding

41. Within a host, receptor molecules can also determine the ________, or tendency to infect a particular tissue type.
a. tropism d. burst size
b. host range e. plaque
c. virulence

ANS: A DIF: Easy REF: 6.5
OBJ: 6.5a Explain how animal viruses exhibit host and tissue tropism
MSC: Remembering

42. The primary factor determining the life cycle of an animal virus is the physical form of the
a. envelope. d. receptor.
b. capsid. e. burst.
c. genome.

ANS: C DIF: Difficult REF: 6.5
OBJ: 6.5c Compare and contrast animal virus replication cycles
MSC: Analyzing

43. The proteins found in animals and plants that can recognize general signs of viral infections are
a. RNA interference. d. surface receptors.
b. interferons. e. antibodies.
c. T-lymphocytes.

ANS: B DIF: Easy REF: 6.5
OBJ: 6.5e Describe animal and plant viral defenses MSC: Remembering