What salty or fresh water does to plant and animal cells

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. Read this first

   Use the table

   Lab card and beaker drawing (model data, not to scale). A teacher soaked celery strips from one stalk; a class reads about the test.

   Salt in the solution (%)	Start mass (g)	End mass (g)	Change in mass (%)
   0	6.0	6.72	12
   2	6.0	6.24	4
   4	6.0	5.76	−4
   6	6.0	5.28	−12

   Percent change = (end mass - start mass) / start mass x 100. Beaker P: salt water, 1% solute. Beaker Q: salt water, 5% solute. Each beaker holds one celery strip from the same stalk.

2. 1.

   Jun uses the card and the two beakers. Which beaker holds a solution hypertonic to the celery cells?

   • Beaker P, because the celery cells hold more solute than P
   • Beaker P, because 1% is closer to the card's 0% row
   • Beaker P, because water moves toward the side with less solute
   • Beaker Q, because 5% is above the balance point near 3%

3. Use the table

   Lab card and beaker drawing (model data, not to scale). A teacher placed a shell-less egg in each liquid; the shell was dissolved in vinegar beforehand.

   Solute in the solution (%)	Start mass (g)	End mass (g)	Change in mass (%)
   0	60	66	10
   10	60	60	0
   40	60	42	−30

   Percent change = (end mass - start mass) / start mass x 100. Beaker D: sugar solution, 25% solute, holding a fourth egg of the same kind with a start mass of 60 g.

4. 2.

   Kira adds beaker D. Which prediction for the fourth egg fits the card?

   • Its mass falls, because 25% is above the egg's 10%
   • Its mass rises, because beaker D is hypotonic to the egg
   • Its mass stays at 60 g, because isotonic means no water moves
   • Its mass rises, because sugar moves into the egg

5. Use this

   Beaker drawing of a paramecium, a single-celled organism (model data, not to scale). After an hour the paramecium has not burst.

6. 3.

   Milo reads that this paramecium sits in a hypotonic medium yet has not burst. What best explains this?

   • Salt flows out of the cell as fast as water flows in
   • The medium is hypertonic to the cell, so water leaves
   • Its contractile vacuole pumps extra water out
   • Water moves toward less solute, so it leaves the cell
7. 4.

   “model data, not to scale” In Noah's drawing the cell contents shrank, yet the wall kept its outline. What best explains this?

   • Salt entered the cell and pushed the membrane inward
   • The cell burst, so the wall was left as an empty outline
   • Water left the cytoplasm, but the stiff wall stayed
   • The wall shrank first, and the membrane followed it

8. Use this

   Beaker drawing (model data, not to scale). One beaker holding one plant cell, drawn as a stiff wall with the membrane just inside it. Inside the cell:

9. 5.

   Pia's notes say a plant cell in fresh water takes in water until it bursts. Which correction fixes the notes?

   • Water enters until the wall resists, so the cell is turgid
   • Salt enters the cell until both sides match
   • Water leaves the cell, so the cell shrinks and wilts
   • Water enters until the cell is isotonic, and then it bursts

10. Use this

    Beaker drawing (model data, not to scale). One beaker holding one plant cell, drawn as a stiff wall with the membrane just inside it. Inside the cell: 4% solute. The beaker: salt water, 10% solute. The cell is a potato cell.

11. 6.

    Ren's notes say the potato strip's mass rises in 10% salt water because salt moves in. Which correction fixes the notes?

    • Salt leaves the strip, so its mass falls
    • The mass holds steady, because no water crosses
    • Water leaves the strip, so its mass falls
    • Water enters the strip, so its mass rises
12. 7.

    Beaker drawing (model data, not to scale). Tala's notes say the solution is hypertonic because the cell holds 6% and the solution 2%. Which correction fixes the notes?

    • The note is right, because the cell holds more solute than the solution
    • The solution is isotonic, because both contain solute
    • The solution is hypotonic, so water leaves the cell
    • It is hypotonic, because it has less solute than the cell
13. 8.

    Zee moves a celery piece from fresh water into beaker S. Which claim, with its reason, fits the drawing?

    • It gains water and bursts, because the wall cannot hold the swelling
    • It loses water, because the cells are hypertonic to 6%
    • It loses water and wilts, because 6% is hypertonic to the cells
    • It gains water, because water moves toward less solute
14. 9.

    After a day in corn syrup the egg lost water and shriveled; a teacher now moves it into beaker W. Ari's teacher moves the shriveled egg from corn syrup into beaker W. Which claim, with its reason, fits?

    • It stays the same, because isotonic means no water moves
    • It swells, because sugar leaves the egg
    • It swells, because water moves toward its higher solute
    • It keeps shrinking, because water moves toward less solute
15. 10.

    Beaker drawing (model data, not to scale). Esme watches a celery cell in beaker Q. Which claim, with its reason, fits the drawing?

    • Its mass falls, because water moves toward less solute
    • Its mass holds steady, because no water crosses the membrane
    • Its mass holds steady, because salt and water swap places
    • Its mass holds steady, because equal water crosses each way