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Chapter 9 Exercises

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    Review Questions for Chapter 9


    Multiple Choice 

    1) The component(s) of a virus that is/are extended from the envelope for attachment is/are the:

    1. capsomeres
    2. spikes
    3. nucleic acid
    4. viral whiskers

    2) Which of the following does a virus lack? Select all that apply.

    1. ribosomes
    2. metabolic processes
    3. nucleic acid
    4. glycoprotein

    3) The envelope of a virus is derived from the host’s

    1. nucleic acids
    2. membrane structures
    3. cytoplasm
    4. genome

    4) In naming viruses, the family name ends with ________ and genus name ends with _________.

    1. −virus; −viridae
    2. −viridae; −virus
    3. −virion; virus
    4. −virus; virion

    5) What is another name for a nonenveloped virus?

    1. enveloped virus
    2. provirus
    3. naked virus
    4. latent virus

    6) Which of the following leads to the destruction of the host cells?

    1. lysogenic cycle
    2. lytic cycle
    3. prophage
    4. temperate phage

    7) A virus obtains its envelope during which of the following phases?

    1. attachment
    2. penetration
    3. assembly
    4. release


    8) Which of the following components is brought into a cell by HIV?

    1. a DNA-dependent DNA polymerase
    2. RNA polymerase
    3. ribosome
    4. reverse transcriptase

    9) A positive-strand RNA virus:

    1. must first be converted to a mRNA before it can be translated.
    2. can be used directly to translate viral proteins.
    3. will be degraded by host enzymes.
    4. is not recognized by host ribosomes.

    10) What is the name for the transfer of genetic information from one bacterium to another bacterium by a phage?

    1. transduction
    2. penetration
    3. excision
    4. translation

    11) Which of the followings cannot be used to culture viruses?

    1. tissue culture
    2. liquid medium only
    3. embryo
    4. animal host

    12) Which of the following tests can be used to detect the presence of a specific virus?

    1. EIA
    2. RT-PCR
    3. PCR
    4. all of the above

    13) Which of the following is NOT a cytopathic effect?

    1. transformation
    2. cell fusion
    3. mononucleated cell
    4. inclusion bodies

    14) Which of these infectious agents do not have nucleic acid?

    1. viroids
    2. viruses
    3. bacteria
    4. prions

    15) Which of the following is true of prions?

    1. They can be inactivated by boiling at 100 °C.
    2. They contain a capsid.
    3. They are a rogue form of protein, PrP.
    4. They can be reliably inactivated by an autoclave.




    16) A virus that infects a bacterium is called a/an ___________________.


    17) A/an __________ virus possesses characteristics of both a polyhedral and helical virus.


    18) A virus containing only nucleic acid and a capsid is called a/an ___________________ virus or __________________ virus.


    19) The ____________ _____________ on the bacteriophage allow for binding to the bacterial cell.


    20) An enzyme from HIV that can make a copy of DNA from RNA is called _______________________.


    21) For lytic viruses, _________________ is a phase during a viral growth curve when the virus is not detected.


    22) Viruses can be diagnosed and observed using a(n) _____________ microscope.


    23) Cell abnormalities resulting from a viral infection are called ____________ _____________.


    24) Both viroids and virusoids have a(n) _________ genome, but virusoids require a(n) _________ to reproduce.


    Short Answers


    25) Discuss the geometric differences among helical, polyhedral, and complex viruses.


    26) What was the meaning of the word “virus” in the 1880s and why was it used to describe the cause of tobacco mosaic disease?


    27) Briefly explain the difference between the mechanism of entry of a T-even bacteriophage and an animal virus.


    28) Discuss the difference between generalized and specialized transduction.


    29) Differentiate between lytic and lysogenic cycles.


    30) Briefly explain the various methods of culturing viruses.


    31) Describe the disease symptoms observed in animals infected with prions.


    Critical Thinking


    . 32) Name each labeled part of the illustrated bacteriophage.
    An illustrated bacteriophage is shown. There are arrows pointing to its different parts labeled A, B, C, and D.

    33) In terms of evolution, which do you think arises first? The virus or the host? Explain your answer.


    34) Do you think it is possible to create a virus in the lab? Imagine that you are a mad scientist. Describe how you would go about creating a new virus.


    35) Label the five stages of a bacteriophage infection in the figure:

    A shows the bacteriophage sitting on the outside of the cell; the phage DNA is inside the phage. The host cell shows host DNA. B shows phage DNA entering host. C shows phage DNA replicates as well as protein particles. D shows new bacteriophages forming. E shows new phage particles exiting host bacterial cell.

    36) Bacteriophages have lytic and lysogenic cycles. Discuss the advantages and disadvantages for the phage.


    37) How does reverse transcriptase aid a retrovirus in establishing a chronic infection?


    38) Discuss some methods by which plant viruses are transmitted from a diseased plant to a healthy one.


    39) Label the components indicated by arrows.

    A plate with a smooth beige background labeled (A). There are holes in this background; these holes are labeled B.

    Figure 6.27 (credit: modification of work by American Society for Microbiology)


    40) What are some characteristics of the viruses that are similar to a computer virus?


    41) Does a prion replicate? Explain.

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