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?

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

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 cross through proteins that use energy from the cell
   • Substances stay on one side because the membrane blocks them
   • 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 gather on one side until the membrane is full
   • Each dot keeps moving in one direction, from outside to inside
   • The dots have stopped moving because the two sides match
   • The dots keep moving, but there is no net movement either way
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?

   • Inside the cell, which holds 12 molecules to 3 outside it
   • 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

6. 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. Letter C points to a protein that reaches all the way across the bilayer and changes shape to carry glucose. Outside the cell: 11 glucose molecules. Inside the cell: 4 glucose molecules.

7. 5.

   Kira reads a drawing of glucose near carrier protein C. How many more glucose molecules are outside the cell than inside?

   • 4 more glucose molecules outside
   • 7 more glucose molecules outside
   • 11 more glucose molecules outside
   • 15 more glucose molecules outside
8. 6.

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

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

9. 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.

10. 7.

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

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

11. 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.

12. 8.

    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?

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

13. Use this

    Lab membrane drawing (model, not to scale). 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 3 solute dots and side 2 holds 9 solute dots. The two sides are the same size.

14. 9.

    Tala's class reads a lab membrane that passes water but not solute. Which way does water move across it on net?

    • From side 2 to side 1, the side with less solute
    • Water stays put, because the membrane stops the solute dots
    • From side 1 to side 2, the side with more solute
    • Both ways equally, because water crosses in both directions
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, down the gradient, with no cell energy
    • They slip between the tails, so J is not needed
    • They move out through J, from fewer ions to more
    • They move in through J, but the cell must spend energy to use it