Diffusion and osmosis

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   Membrane drawing (model, not to scale). No proteins are drawn. The two sides are the same size. Ari reads the term concentration gradient beside a drawing. What does a concentration gradient mean?

   • A difference in how crowded a substance is between two places
   • The energy a cell spends to move a substance across a membrane
   • A tunnel in a protein that lets a substance cross a membrane
   • The point where a substance stops moving in a space

2. Read this first

   Use this

   Membrane drawing (model, not to scale). No proteins are drawn.

3. 2.

   A label on Bo's drawing says passive transport. What does passive transport mean?

   • Substances stay on one side because the membrane blocks them
   • Substances cross through proteins that use energy from the cell
   • Substances move across a membrane and the cell spends no energy
   • Substances move across a membrane using energy the cell supplies
4. 3.

   Both sides of Esme's drawing hold 5 dots, and a label says dynamic equilibrium. What does that mean?

   • The dots have stopped moving because the two sides match
   • Each dot keeps moving in one direction, from outside to inside
   • The dots keep moving, but there is no net movement either way
   • The dots gather on one side until the membrane is full
5. 4.

   Membrane drawing (model, not to scale). No proteins are drawn. The two sides are the same size. In Jun's drawing, the two sides are the same size. Which side has the higher concentration of oxygen?

   • Outside the cell, which holds 12 molecules to 3 inside
   • Neither side, because the two sides are the same size
   • Inside the cell, because it is behind the membrane
   • Inside the cell, which holds 12 molecules to 3 outside it

6. Use this

   Lab card (model data). Dots on each side of a lab membrane. Table with 3 rows. Columns: Time (minutes) | Side 1 dots | Side 2 dots. Rows: 0 | 12 | 0; 5 | 8 | 4; 10 | 6 | 6. Dots could cross in both directions. A teacher ran the test; read about only.

7. 5.

   Luz's class reads dots on each side of a lab membrane they cross. At which time were the two sides equal?

   • At 0 minutes, when side 1 held 12 dots
   • At 5 minutes, when side 2 held 4 dots
   • At 10 minutes, when each side held 6 dots
   • At no time, because the dots stopped moving before then

8. Use this

   Two membrane drawings (model, not to scale). Each has a bilayer of phospholipids, no proteins, watery fluid outside the cell above and watery fluid inside the cell below. Drawing 1: 10 oxygen molecules outside and 2 inside. Drawing 2: 6 oxygen molecules outside and 6 inside.

9. 6.

   Milo compares two drawings of oxygen near a membrane. Which drawing shows equilibrium?

   • Drawing 2, because the dots have stopped moving across the membrane
   • Neither drawing, because moving dots mean no equilibrium
   • Drawing 1, because the outside holds the most dots
   • Drawing 2, because the counts match, so net movement is zero
10. 7.

    Two membrane drawings (model, not to scale). Noah compares two drawings of oxygen crossing a membrane. Which drawing best shows how the molecules move?

    • Neither drawing, because molecules cannot cross without a protein
    • Drawing 2, because each molecule moves from the crowded side to the other
    • Drawing 1, because molecules move both ways, with more going inward
    • Drawing 2, because the cell spends energy to send molecules inward

11. Use this

    Two lab membrane drawings (model, not to scale). Each has a selectively permeable membrane with fluid on side 1 above and fluid on side 2 below. Water crosses the membrane; solute dots cannot. Side 1 holds 2 solute dots and side 2 holds 8 solute dots, in both drawings. Drawing 1: the water arrow points from side 1 to side 2. Drawing 2: the water arrow points from side 2 to side 1.

12. 8.

    Pia compares two drawings of a lab membrane that passes water but not solute. Which drawing shows the way water moves?

    • Neither drawing, because the solute dots block the water
    • Drawing 1, because the solute dots follow the water arrow across
    • Drawing 2, because water moves toward the side with less solute
    • Drawing 1, because water moves toward the side with more solute

13. Use this

    Membrane drawing (model, not to scale). A bilayer of phospholipids with watery fluid outside the cell above and watery fluid inside the cell below. No proteins are drawn. Outside the cell: 4 carbon dioxide molecules. Inside the cell: 13 carbon dioxide molecules. The two sides are the same size.

14. 9.

    Ren watches a model of carbon dioxide near a cell membrane. Which way do the molecules move on net, and does the cell spend energy?

    • Out of the cell, with no molecule moving in at the same time
    • Into the cell, from fewer molecules to more, with no energy from the cell
    • Out of the cell, down the gradient, powered by energy from the cell
    • Out of the cell, down the gradient, with no energy from the cell
15. 10.

    Membrane drawing (model, not to scale). Zee reads a drawing of sodium ions and channel protein J. Which statement about sodium ions crossing through J is right?

    • They move in through J, but the cell must spend energy to use it
    • They move out through J, from fewer ions to more
    • They slip between the tails, so J is not needed
    • They move in through J, down the gradient, with no cell energy