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?

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

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?

   • 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
   • Disagree: antibiotics are for bacteria, and a virus is a different kind of germ
   • 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: having a plasma membrane is enough for a virus to attach to a cell
   • Disagree: phage T is far too large to fit inside a human cell, whatever its receptors
   • Agree: a virus copies itself in any cell it manages to enter, even a human 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?

   • 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
   • 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

7. Comparison table (model data, from OpenStax Biology 2e)

   germ	who does most of the copying work
   bacterium	its own ribosomes and enzymes
   virus	the host cell's ribosomes and enzymes

8. 5.

   Milo asks why a drug against a virus is harder to design than a drug against a bacterium. Which explanation fits the table?

   • A virus has its own ribosomes, and they are the same as the host cell's ribosomes
   • A virus copies itself outside cells, where no drug can enter or reach it
   • A virus uses host-cell machinery, so a drug aimed at it could harm host cells
   • A virus has no genetic material for a drug to reach, so it cannot be blocked

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?

    • Neither cycle, because free phage particles copy themselves in the dish
    • Lysogenic cycle, because the phage DNA is hidden in the bacteria
    • Lytic cycle, because the number of bacteria stayed the same
    • Lytic cycle, because bacteria fell while free phage particles rose
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
    • 25
    • 32
    • 64
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
    • Some prophages left the host DNA and began the lytic cycle
    • Free phage particles copied themselves in the dish until the bacteria ran low
    • The phage DNA joined the host DNA for the first time
13. 9.

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

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

14. Lab notebook (model data)

    sample	what is seen after 1 day
    phage sample alone in a clean dish	no new phage particles
    bacteria alone in broth	more bacteria and no phage particles
    phage sample added to bacteria in broth	many new phage particles

15. 10.

    Pia reads a lab notebook about a phage sample. Which statement explains what the notebook shows?

    • A phage divides in two on its own, but slowly in a clean dish
    • A phage has its own ribosomes, so it copies itself in any dish
    • A phage copies itself only inside a host cell, so it needs the bacteria
    • The bacteria are bystanders, since a phage copies itself in whatever cell is near