Viruses compared with cells, and how viruses spread

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Kira's friend says a virus is a tiny cell, because it has genetic material and a protective coat. Which response uses the table?

   • Disagree: a virus lacks ribosomes, a membrane of its own and metabolism
   • Agree: a virus has ribosomes and a membrane, like the bacterium
   • Disagree: a virus is a cell, but it is much larger than a bacterium
   • Agree: genetic material in a protective coat is what makes something a cell

2. Read this first

   Use this

   Fact card (CDC, paraphrased). Antibiotics are medicines for certain infections caused by bacteria. A virus is a different kind of germ from a bacterium. Antibiotics do not work on viruses, such as the ones behind colds and flu.

3. 2.

   Zee's friend says an antibiotic should work on a cold virus, because antibiotics act on germs. Which response agrees with the fact card?

   • Disagree: antibiotics are for bacteria, and a virus is a different kind of germ
   • Agree: a cold virus is a very small bacterium, so an antibiotic acts on it
   • Disagree: an antibiotic acts on germs, but a cold virus is too small for it to reach
   • Agree: antibiotics act on germs, and a virus is a germ, so they work on it

4. Use this

   Host table (model data), 3 rows. Columns: virus, attaches to cells with. phage T, receptor R, found on certain bacteria; plant virus V, receptor S, found on cells of one kind of plant; virus M, receptor U, found on certain animal cells.

5. 3.

   Ari's friend says phage T could infect human cells, because every cell has a plasma membrane. Which response uses the table?

   • Disagree: phage T needs receptor R, which is found on certain bacteria
   • Agree: a virus copies itself in any cell it manages to enter, even a human cell
   • Disagree: phage T is far too large to fit inside a human cell, whatever its receptors
   • Agree: having a plasma membrane is enough for a virus to attach to a cell
6. 4.

   Drug W stops a cell from building its cell wall. Ren reads that drug W stops cells from building a cell wall. Using the table, why does drug W have no target in a virus particle?

   • The drug does act on a virus, by stopping it from building a capsid
   • A virus particle is too small for the drug to reach
   • A virus has a cell wall, but it is built inside the host cell
   • A virus particle has no cell wall for the drug to act on

7. Drug table (model data)

   drug	what it blocks	found in healthy host cells
   W	building a bacterial cell wall	no
   X	a protein made only by the virus	no
   Y	a protein that host cells need	yes

8. 5.

   Luz reads a drug table. Which drug could slow a virus while sparing host cells?

   • No drug can slow a virus, because a virus has nothing that a drug can block
   • Drug X, because its target is a viral protein that host cells lack
   • Drug W, because a virus must build a cell wall to copy itself
   • Drug Y, because a protein that host cells need is a safe target

9. Model data for phage P

   time in minutes	bacteria in the dish	free phage particles
   0	1,000	0
   30	1,000	0
   60	100	9,000

10. 6.

    Bo reads model data from a dish of bacteria with phage P. Which cycle do the data best fit?

    • Lytic cycle, because bacteria fell while free phage particles rose
    • Neither cycle, because free phage particles copy themselves in the dish
    • Lytic cycle, because the number of bacteria stayed the same
    • Lysogenic cycle, because the phage DNA is hidden in the bacteria
11. 7.

    Each time a bacterium divides, its prophage is copied into both new cells. Esme reads model data on bacteria that carry a prophage. If the pattern continues, how many bacteria carry the prophage after 5 divisions?

    • 10
    • 64
    • 25
    • 32
12. 8.

    The dish conditions changed between hour 2 and hour 4. Tala reads model data on bacteria that carry a prophage. What happened between hour 2 and hour 4?

    • The phage began the lysogenic cycle, because free phage particles appeared
    • Free phage particles copied themselves in the dish until the bacteria ran low
    • Some prophages left the host DNA and began the lytic cycle
    • The phage DNA joined the host DNA for the first time
13. 9.

    Noah notices that an enveloped virus is wrapped in a membrane. Does the envelope make the virus a cell?

    • No: the envelope lets the virus attach to any cell it meets and enter it
    • Yes: the envelope is a plasma membrane that the virus makes itself
    • Yes: anything wrapped in a membrane is a cell, whatever else it lacks
    • No: the envelope is host-cell membrane, and the virus has no ribosomes
14. 10.

    1 µm = 1,000 nm. Jun sees that a giant virion is wider than a small bacterium. What does this show?

    • The table is wrong, because virions are narrower than bacteria
    • The giant virion is a cell, because it is wider than any small bacterium
    • Width does not decide: a virion lacks cell structure however wide it is
    • The giant virion is a bacterium, because it carries genetic material