Diffusion and osmosis

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Ari reads a graph of particles on two sides of a membrane they cross. What does the flat part of both lines, after 30 minutes, show?

   • The sides are equal near 50, with particles still crossing both ways
   • Particles crossed from side 1 to side 2, and no particle crossed back
   • The membrane ran out of energy for moving particles at 30 minutes
   • Particles stopped crossing once the sides reached 50
2. 2.

   Bo reads a graph of one substance crossing a membrane in warm water and in cold water. Which conclusion does the graph support?

   • Warmth changes the end point: warm water ends higher than cold
   • Cold water is slower because the membrane spends less energy there
   • Warm particles stop moving after 30 minutes, when the line goes flat
   • Warmth raises the rate but not the end point: both reach 50
3. 3.

   Esme reads a graph of one substance moving into a lab chamber. The line climbs steeply, then flattens. Why does the climb slow down?

   • The gradient shrinks as the chambers near equal, so diffusion slows
   • The chamber is running low on energy to power diffusion
   • Particles slow down and stop moving as the line flattens
   • Particles cross into the chamber and do not cross back, so the first empties

4. Read this first

   Use this

   Lab card (model data). A U-tube had a membrane across the bottom that passes water but not sugar. The left arm held 3 sugar dots and the right arm held 9 at the start, and both levels began at 20 mL. Table with 3 rows. Columns: Time (minutes) | Left level (mL) | Right level (mL). Rows: 0 | 20 | 20; 10 | 17 | 23; 20 | 15 | 25. A teacher ran the test; read about only.

5. 4.

   Kira reads a card for a U-tube with a membrane that passes water but not sugar. Which conclusion does the card support?

   • Water moved right to left, toward less sugar, as the right level rose
   • Water moved left to right, toward more sugar, as the left level fell 3 mL by 20 minutes
   • Water moved left to right, toward more sugar, as the left level fell 5 mL by 20 minutes
   • Sugar dots crossed to the right arm and raised its level

6. Use this

   Lab card (model data). A lab-made bilayer held 10 carrier proteins for glucose. The card gives the glucose outside and the rate of crossing. Table with 4 rows. Columns: Glucose outside (units) | Rate (molecules per second). Rows: 2 | 5; 4 | 9; 8 | 12; 16 | 12. A teacher ran the test; read about only.

7. 5.

   Luz reads a card about glucose crossing through carrier proteins. The rate stays at 12 when glucose outside rises from 8 to 16. Why?

   • Glucose crossed the bilayer alone at 16 units, so carriers were not needed
   • The carriers ran out of cell energy once glucose reached 8 units
   • Glucose stopped moving at 8 units, because the sides reached equilibrium
   • Every carrier was busy, so more glucose could not raise the rate

8. Use this

   Notes card written by a student. Line 1: Diffusion moves a substance from higher to lower concentration. Line 2: The cell spends ATP to run diffusion. Line 3: Warmer conditions speed diffusion up.

9. 6.

   Milo's notes on diffusion have three lines. One line is wrong. Which correction fixes the notes?

   • Line 3 is wrong: warmer conditions slow diffusion down
   • Line 2 is right: diffusion through proteins also spends ATP
   • Line 1 is wrong: substances move from lower to higher concentration
   • Line 2 is wrong: diffusion is passive, so the cell spends no ATP

10. Use this

    Notes card written by a student. The left arm holds 2 sugar dots and the right arm holds 8. Line 1: Sugar cannot cross the membrane. Line 2: Water crosses, so water moves toward the left arm, where there is less sugar. Line 3: The left level will rise.

11. 7.

    Noah's notes explain a U-tube with a membrane that passes water but not sugar. One line is wrong. Which correction fixes the notes?

    • Water moves to the right arm, which has more sugar, so its level rises
    • Water moves to the left arm, which has less sugar, so its level rises
    • Sugar moves to the left arm, which has less sugar, so its level rises
    • Water moves to the right arm, which has more sugar, so its level falls
12. 8.

    Pia's notes say a molecule in diffusion only moves from high to low concentration, so it never moves back. Which correction fixes the notes?

    • Molecules move both ways, but more move outward, so the net movement is outward
    • Molecules move both ways until equilibrium, and then they stop moving
    • Molecules move at random both ways; the net movement is from high to low
    • No correction: molecules move from high to low, and a move back needs cell energy
13. 9.

    Ren compares claims about glucose and carrier protein C when both sides hold 8 glucose molecules. Which claim, with its reason, fits?

    • Net movement inward, because the carrier points toward the inside
    • No net movement of glucose, because the two sides match and the gradient is gone
    • Net movement inward, because the carrier uses cell energy to pull glucose in
    • No glucose crosses, because the carrier stops working when the sides match
14. 10.

    Lab drawing (model, not to scale). Zee reads about a bag of lab membrane that passes water but not starch. Which claim about water, with its reason, fits?

    • Water moves out of the bag, because it moves toward the side with less starch
    • Water moves into the bag, because the beaker has more free water
    • Water moves into the bag, because water molecules move in one direction
    • Water moves into the bag, because the membrane spends energy to pull it in