Diffusion and osmosis

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Use this

   Lab card (model data). Coloring particles in two chambers joined by a membrane they can cross. Table with 3 rows. Columns: Time (minutes) | Left chamber | Right chamber. Rows: 0 | 24 | 0; 5 | 16 | 8; 10 | 13 | 11. A teacher ran the test; read about only.

2. 1.

   Ari's class reads counts of food-coloring particles in two chambers joined by a membrane they can cross. What will the counts be after a long time?

   • About 24 in the right chamber, because particles end up on the far side
   • About 12 in each chamber, with particles no longer crossing
   • About 12 in each chamber, though no particle crosses back to the left
   • About 12 in each chamber, with particles still crossing both ways
3. 2.

   No proteins are drawn. Esme reads a drawing with two gases near a cell membrane. Each gas crosses the bilayer alone. Which statement predicts the net movement?

   • Oxygen moves in, and the cell spends energy to move carbon dioxide out
   • Oxygen moves in and carbon dioxide out, each down its own gradient
   • Both gases move in, because the outside holds more molecules in total
   • Oxygen moves out and carbon dioxide moves in, because gases swap places

4. Use this

   Lab card (model data). Time for food coloring to spread to the far side of a cup. Table with 2 rows. Columns: Water | Time to spread (seconds). Rows: warm water | 30; cold water | 90. The cups were the same size and held the same amount of water. A teacher ran the test; read about only.

5. 3.

   Jun's class drops food coloring into two cups of water and times how long the color takes to reach the far side. What does the card show?

   • The cups match, because diffusion is passive and needs no energy
   • Warmer water slows diffusion, because particles crowd together
   • Warmer water speeds diffusion, because particles have more thermal energy
   • Cold water spreads color faster, because dense water pushes particles along
6. 4.

   Kira compares two cells where oxygen crosses the bilayer alone. Which cell has the faster net diffusion, and why?

   • Cell 1, because the cell spends more energy when the gradient is steep
   • Cell 2, because molecules move faster when the sides are closer to equal
   • Cell 1, because a larger difference in concentration speeds diffusion
   • The rates match, because both cells have more oxygen outside

7. Use this

   Lab card (model data). Time for each substance to spread across a tank. Table with 2 rows. Columns: Substance | Molecule mass | Time to spread (seconds). Rows: L | lighter | 40; H | heavier | 100. Both tanks held the same warm water and the same starting gradient. A teacher ran the test; read about only.

8. 5.

   Luz's class reads a card with two substances in the same warm tank. A third substance, M, has molecules heavier than L's but lighter than H's. Predict M's time.

   • Between 40 and 100 seconds, since heavier molecules diffuse more slowly
   • Exactly 140 seconds, since the two times add together
   • Under 40 seconds, since heavier molecules diffuse faster
   • Exactly 40 seconds, since the same gradient gives the same time
9. 6.

   model, not to scale. Chloride ions cross a cell membrane through channel protein H, from 14 molecules outside to 5 inside. Milo classifies the transport. Which label fits?

   • Facilitated diffusion: passive, through a protein, down the gradient
   • Osmosis: chloride ions crossing toward the side with more water
   • Facilitated diffusion: through a protein, using energy from the cell
   • Simple diffusion: passing between the tails, down the concentration gradient
10. 7.

    Noah sorts four transport events shown on a membrane drawing. Which event is simple diffusion?

    • Carbon dioxide slips between the tails, powered by cell energy
    • Chloride ions pass through channel L, down their gradient
    • Glucose binds carrier M, which spends cell energy to change shape
    • Oxygen slips between the tails, down its gradient, with no protein
11. 8.

    Lab membrane drawing (model, not to scale). Pia reads a drawing of aquaporin channels in a lab membrane. Water crosses, but solute cannot. Which label fits the water movement?

    • Facilitated diffusion: the cell spends energy to open the aquaporin
    • Osmosis: movement of water that the cell powers with its energy
    • Osmosis: passive movement of water toward the side with less solute
    • Osmosis: passive water movement toward the side with more solute
12. 9.

    Solute dots cannot cross either membrane. Each side is the same size. Tala reads two lab chambers, each split by a membrane that passes water but not solute. In which chamber does water move on net, and which way?

    • Both chambers, from side A to side B, since water moves in one direction
    • Chamber 2, from side A to side B, because its sides are equal
    • Chamber 1, from side B to side A, where solute is lower
    • Chamber 1, from side A to side B, where solute is higher
13. 10.

    Zee compares two U-tubes with a membrane that passes water but not sugar. Which tube shows the faster net movement of water, and why?

    • Tube 2, because its arms differ more in sugar, so water moves faster
    • Tube 2, because the membrane spends more energy on a bigger difference
    • Tube 1, because its arms are closer to equal, so water moves faster
    • The tubes match, because water moves toward the right arm in both