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 potato strips from one potato; a class reads about the test.

   Salt in the solution (%)	Start mass (g)	End mass (g)	Change in mass (%)
   0	4.0	4.8	20
   2	4.0	4.4	10
   5	4.0	3.8	−5
   10	4.0	2.8	−30

   Percent change = (end mass - start mass) / start mass x 100. Beaker Z: salt water, 3% solute, holding one strip from the same potato.

2. 1.

   Bo puts a strip from the same potato in beaker Z. Which prediction fits the card?

   • It gains mass, because 3% is under the balance point near 4%
   • It stays the same, because isotonic means no water moves
   • It loses mass, because water moves toward the side with less solute
   • It gains mass, because salt moves in from beaker Z into the strip

3. 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.

4. 2.

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

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

5. 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: 3% solute. The beaker: fresh water, 0% solute; after 30 minutes the cell is larger and firm, and it has not burst. The wall is drawn stiff, with the membrane pressed against it.

6. 3.

   Water entered Luz's plant cell, yet the cell did not burst. What best explains this?

   • Salt left the cell and balanced the water that came in
   • Water moves toward less solute, so it stopped at the wall
   • The membrane blocks water once the cell is full
   • The wall pushes back, building turgor pressure

7. Use this

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

8. 4.

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

   • Water moves toward less solute, so it leaves the cell
   • Its contractile vacuole pumps extra water out
   • The medium is hypertonic to the cell, so water leaves
   • Salt flows out of the cell as fast as water flows in
9. 5.

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

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

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:

11. 6.

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

12. 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.

13. 7.

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

    • The mass holds steady, because no water crosses
    • Water enters the strip, so its mass rises
    • Salt leaves the strip, so its mass falls
    • Water leaves the strip, so its mass falls
14. 8.

    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
    • It is hypotonic, because it has less solute than the cell
    • The solution is isotonic, because both contain solute
    • The solution is hypotonic, so water leaves the cell
15. 9.

    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 gains water, because water moves toward less solute
    • It loses water and wilts, because 6% is hypertonic to the cells
    • It loses water, because the cells are hypertonic to 6%
16. 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 holds steady, because salt and water swap places
    • Its mass holds steady, because no water crosses the membrane
    • Its mass falls, because water moves toward less solute
    • Its mass holds steady, because equal water crosses each way