Viruses compared with cells, and how viruses spread

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   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 envelope, a layer of host-cell membrane
   • The plasma membrane, which the virus makes itself
   • The capsid, the coat made of protein
   • The nucleus, which holds the viral DNA
2. 2.

   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
   • A ribosome, which reads the instructions
   • The nucleus, which holds the viral DNA
   • The capsid, which holds a plan for each protein
4. 3.

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

   • Outside both circles, so neither has ribosomes
   • In the overlap, so a virus has ribosomes too
   • In the virus circle only, so cells have none
   • In the cell circle only, so a virus has none
5. 4.

   Kira uses the Venn diagram to place a fact about copying. Which sentence agrees with the diagram?

   Use the picture in question 3.

   • A virus copies itself only in a host cell, so this fact is in the virus circle
   • A virus divides in two the way a bacterium does, so this fact is in the overlap
   • A virus copies itself on its own, so this fact is in the overlap with cells
   • A virus copies itself in a host cell, so this fact is in the cell circle
6. 5.

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

   Use the picture in question 3.

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

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 that a virus cannot attach to because it lacks a receptor
   • 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

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 tiny bacterium that is covered by a protein coat
    • A virus that infects plant cells and animal cells
    • A virus that infects bacteria as its host cells
    • 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?

    • 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
    • A small cell with a protein coat and genetic material
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?

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

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?

    • The widest prokaryotic cell, 5.0 µm, is narrower than the widest virion, 250 nm
    • 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
    • A virion is wider than a eukaryotic cell, because 250 is more than 100