Viruses compared with cells, and how viruses spread

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Ari compares a bacterium with a virus in a model drawing. Letter B points to the protein layer around the virus's genetic material. What is B called?

   • The capsid, a coat made of protein
   • A cell wall, as on the bacterium
   • A ribosome, a structure that builds proteins
   • The envelope, a membrane around the coat
2. 2.

   Model drawing, not to scale: an animal cell cutaway beside an enveloped virus. Bo studies a model drawing of an enveloped virus beside a host cell. Letter C points to the outer layer, made from host-cell membrane. What is C called?

   • The capsid, the coat made of protein
   • The nucleus, which holds the viral DNA
   • The envelope, a layer of host-cell membrane
   • The plasma membrane, which the virus makes itself
3. 3.

   Model drawing, not to scale: a plant cell cutaway beside a virus. Esme reads a model drawing of a virus beside a plant cell. Letter A points to the part with the instructions for making new virus particles. What is A?

   • The genetic material, which is DNA or RNA
   • The capsid, which holds a plan for each protein
   • A ribosome, which reads the instructions
   • The nucleus, which holds the viral DNA
5. 4.

   Jun reads a Venn diagram that compares a virus with a cell. In which part is the word ribosomes written?

   • In the overlap, so a virus has ribosomes too
   • In the cell circle only, so a virus has none
   • In the virus circle only, so cells have none
   • Outside both circles, so neither has ribosomes
6. 5.

   Luz checks the Venn diagram. Which feature do a virus and a cell both have?

   Use the picture in question 4.

   • A protein coat called a capsid
   • A nucleic acid as genetic material
   • Ribosomes that build proteins
   • A plasma membrane of its own

7. Read this first

   Use this

   Word card (model). The word to define is host cell. Examples named on the card: a bacterium for a bacteriophage; a plant cell for a plant virus. Not to scale.

8. 6.

   Milo learns the term host cell for viruses. Which meaning is right?

   • A cell in which a virus copies itself on its own, with no help
   • A cell that a virus enters and uses to make new virus particles
   • A small cell made of genetic material wrapped in a protein coat
   • A cell that a virus cannot attach to because it lacks a receptor

9. Use this

   Word card (model). The word to define is bacteriophage. Examples named on the card: a phage with a head and a tail. Not to scale.

10. 7.

    Noah meets the word bacteriophage on a word card. Which meaning is right?

    • A virus that infects bacteria as its host cells
    • A virus that infects plant cells and animal cells
    • A tiny bacterium that is covered by a protein coat
    • A bacterium that makes copies of itself inside a virus

11. Use this

    Word card (model). The word to define is virion. Examples named on the card: one virus particle sitting outside any host cell. Not to scale.

12. 8.

    Pia meets the word virion on a word card. Which meaning is right?

    • A small cell with a protein coat and genetic material
    • The protein coat of a virus, with nothing inside
    • A single virus particle outside a host cell
    • A virus that has copied itself many times
13. 9.

    1 µm = 1,000 nm. Tala measures three model particles, P, Q and R. Using the table, which one is most likely a virion?

    • P and Q, because both are smaller than a eukaryotic cell
    • R, because a virus is larger than a cell
    • P, because 80 nm is inside the virion range
    • Q, because 3 µm is inside the virion range

14. Widths table (real data, from OpenStax Biology 2e; 1 µm = 1,000 nm)

    particle	width in nm	width in µm
    most virions	20 to 250	0.02 to 0.25
    prokaryotic cell	100 to 5,000	0.1 to 5.0
    eukaryotic cell	10,000 to 100,000	10 to 100

15. 10.

    Zee compares the widest virion in the table with the narrowest eukaryotic cell. Which statement agrees with the table?

    • A virion is wider than a eukaryotic cell, because 250 is more than 100
    • The widest virion in the table, 0.25 µm, is narrower than the narrowest eukaryotic cell, 10 µm
    • A virion and a eukaryotic cell overlap in width, between 20 and 100
    • The widest prokaryotic cell, 5.0 µm, is narrower than the widest virion, 250 nm