chapter 25 quiz
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Wendell Stanley helped influence the development of virology by suggesting that the agent infecting tobacco leaves might be
A. chemicals rather than primitive cells.
B. larger than most bacteria.
C. caused by a crystallized life-form - A. chemicals rather than primitive cells.
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Which of the following statements does not provide a valid comparison between viruses and cells?
A. A virus cannot grow, achieve homeostasis, or metabolize, but a cell can.
B. A virus cannot mutate, but a cell can.
C. A virus can rep - B. A virus cannot mutate, but a cell can.
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A virusÂ’s structural features could include a(n)
A. envelope.
B. capsid.
C. dRNA genome.
D. All of the above - D. All of the above -All viruses have a nucleic acid consisting of either DNA or RNA and a protein coat, called a capsid, surrounding the nucleic acid. Some viruses also have an envelope.
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A virusÂ’s shape is determined by
A. the shape of its capsid.
B. its organelles.
C. its glycoprotein.
D. its envelope. - A. the shape of its capsid.
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Which of the following statements is false?
A. Viruses can be grouped as either RNA viruses or DNA viruses.
B. Viruses can be grouped based on whether their nucleic acid is single-stranded or double-stranded.
C. Viruses can be classi - C. Viruses can be classified based on evolutionary relationships.
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Which of the following is not an example of how a virus might be grouped?
A. helical, enveloped
B. helical, Gram-positive
C. icosahedral, non-enveloped
D. complex brick-shaped, enveloped - B. helical, Gram-positive
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Viruses are called obligate intracellular parasites because they
A. replicate in the material between cells.
B. feed on cells from the inside out.
C. need a host cell to replicate.
D. must live inside cells. - C. need a host cell to replicate.
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How is a bacteriophage different from viruses that cause colds?
A. Bacteriophages infect bacteria.
B. Bacteriophages have a unique replication cycle.
C. Bacteriophages contain a nucleic acid.
D. Bacteriophages have a unique sh - A. Bacteriophages infect bacteria.
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Which of the following phases are not part of the lytic cycle?
A. attachment and entry
B. integration and cell multiplication
C. replication and assembly
D. lysis and release - B. integration and cell multiplication
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How is the lytic cycle different from the lysogenic cycle?
A. In the lytic cycle, a virus's genes are copied each time the cell divides. In the lysogenic cycle, new viruses burst out of the cell.
B. In the lytic cycle, viruses begin to repl - B. In the lytic cycle, viruses begin to replicate immediately. In the lysogenic cycle, viral genes may remain inactive for long periods of time.
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Which of the following comparisons between a virulent virus and a temperate virus is true?
A. Virulent viruses kill their host cells immediately, while temperate viruses do not.
B. Virulent viruses and temperate viruses replicate in the sam - A. Virulent viruses kill their host cells immediately, while temperate viruses do not.
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Which of the following best describes a provirus?
A. an intracellular bacteriophage that is harmless to the host cell
B. a viral DNA molecule produced by reverse transcriptase
C. budding viral particles
D. part of a cell membr - B. a viral DNA molecule produced by reverse transcriptase
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Which of the following statements about viral evolution is false?
A. Viruses probably evolved from early cells.
B. Early simple viruses probably evolved genes that allowed them to invade healthy cells.
C. The first viruses were proba - D. Viruses probably evolved from bacteria that are immune to antibiotics.
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Which of the following diseases is not caused by a virus?
A. the common cold
B. the flu
C. AIDS
D. scarlet fever - D. scarlet fever
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Chickenpox is related to which of the following viruses?
A. shingles
B. cowpox
C. smallpox
D. hepatitis - A. shingles
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What is the most effective weapon for fighting the spread of viral diseases?
A. antibiotics
B. antiviral drugs
C. vaccines
D. plenty of sleep and fluids - C. vaccines
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Some vaccines consist of inactivated or attenuated viruses. Which of the following statements about inactivated and attenuated viruses is true?
A. Inactivated viruses have been temporarily inactivated, and attenuated viruses do not replicate in a - B. Inactivated viruses do not replicate in a host, and attenuated viruses have been genetically altered so that they cannot cause disease.
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Which of the following statements is false?
A. No naturally acquired cases of smallpox have been recorded in more than two decades.
B. Smallpox once killed 40 percent of all people infected.
C. Smallpox is a DNA virus transmitted by - D. The genetic diversity and mutability of the smallpox virus have made developing a vaccine difficult; however, educating people has proven effective in slowing the disease
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Which of the following is not a purpose of antiviral agents?
A. to interfere with the synthesis of nucleic acids
B. to interfere with the synthesis of viral capsids
C. to work with antibiotics to destroy bacteria that viruses have in - C. to work with antibiotics to destroy bacteria that viruses have invaded
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Today, new viruses that affect humans may emerge from
A. recently cleared forests.
B. isolated habitats.
C. virus-infected animals.
D. All of the above - D. All of the above
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Which of the following viruses is linked to cancer?
A. hepatitis B
B. chickenpox
C. influenza
D. rabies - A. hepatitis B