What salty or fresh water does to plant and animal cells

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   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.

2. 1.

   Ari's class views an onion skin cell that holds 2% solute in 7% salt water. How is the solution described?

   • Hypotonic, because the cell's 2% is less than 7%
   • Hypertonic, because 7% is more solute than the cell's 2%
   • Isotonic, because both sides of the membrane contain some solute
   • Hypertonic, because salt moves into the cell
3. 2.

   An Elodea leaf cell holds 3% solute. Bo puts it in circle water with 0.2% solute. How is the water described?

   • Isotonic, because no water moves in or out
   • Hypertonic, because the cell's 3% is more than 0.2%
   • Hypotonic, because 0.2% is less than the cell's 3%
   • Hypotonic, because water moves toward less solute
4. 3.

   A teacher's shell-less egg holds 10% solute. Esme sees it in a 10% sugar solution. How is the solution described?

   • Hypertonic, because the egg holds 10% solute
   • Isotonic, because no water moves in or out
   • Isotonic, because the solution matches the egg's 10%
   • Hypotonic, because sugar can move into the egg
5. 4.

   “model data, not to scale; the shell was dissolved in vinegar by the teacher beforehand” Jun watches a teacher place the shell-less egg in corn syrup. What happens to its mass, and why?

   • It stays the same, because the membrane blocks water
   • It falls, because water moves out of the egg
   • It rises, because water moves toward less solute
   • It rises, because sugar moves into the egg
6. 5.

   Luz puts a crisp lettuce leaf in 8% salt water. What happens to its cells?

   • Water leaves, the membrane pulls from the wall, the leaf wilts
   • Nothing changes, because the wall blocks water from moving
   • Water enters and the cells burst open, so the leaf tears
   • Water enters the cells, so the leaf turns crisper

7. Use the table

   Lab card for one potato strip (model data, a class reads about a teacher's test)

   Salt in the solution (%)	Start mass (g)	End mass (g)
   10	5.0	4.0

   Percent change = (end mass - start mass) / start mass x 100.

8. 6.

   Milo reads the card for one potato strip. What is the percent change in mass, and what moved?

   • A 25% decrease, because water left the strip
   • A 1% decrease, because water left the strip
   • A 20% increase, because salt moved into the strip
   • A 20% decrease, because water left the strip
9. 7.

   Noah reads the card for a teacher's shell-less egg in plain water. What is the percent change in mass, and why?

   • A 9.1% increase, because water entered the egg
   • A 6% increase, because water entered the egg
   • A 10% decrease, because water moved toward less solute
   • A 10% increase, because water entered the egg
10. 8.

    Ren reads a graph of potato strips soaked in salt solutions. At about what salt percent is the solution isotonic to the potato cells?

    • 4%, where no water moves in or out
    • 10%, where the line ends
    • 4%, where the change in mass is 0
    • 0%, where the strips gained the most
11. 9.

    Tala uses the graph of potato strips. What happens to the cells in the 1% salt solution, and why?

    • Water enters, because the 1% solution is hypotonic to the cells
    • Water leaves, because water moves toward less solute
    • Water enters, because the cells are hypotonic to the 1% solution
    • Salt enters, which raises the mass by 10%
12. 10.

    Zee reads the point at 10% salt on the graph. What does that point show?

    • The 10% solution is hypotonic, so water left
    • The strip gained 30% of its mass, because water entered
    • The strip lost 30% of its mass, because water left
    • The strip lost 30% of its mass, because salt left