Diffusion across a cell membrane

Grade 7 Science Worksheet

Circle the best answer.

1. 1.

   Cell arrow diagram (model data, not to scale). No arrows are drawn yet. Which way does each gas move across this membrane, Ari?

   • Both gases move out
   • Oxygen out, carbon dioxide in
   • Oxygen in, carbon dioxide out
   • Both gases move in
2. 2.

   model data, not to scale. A leaf cell in sunlight uses carbon dioxide and makes oxygen. Which way does each gas move, Bo?

   • Both gases move in
   • Neither moves in sunlight
   • Oxygen in, carbon dioxide out
   • Carbon dioxide in, oxygen out
3. 3.

   During a run, Esme's muscle cells use oxygen quickly to release energy from food. Why does oxygen keep moving into them?

   • Oxygen is made inside the cells
   • The cells pull oxygen in with energy
   • The cells pump carbon dioxide in
   • Using it keeps the inside count low
4. 4.

   Cell arrow diagram (model data, not to scale). No arrows are drawn yet. Now there are 6 oxygen dots on each side. What are the oxygen particles doing, Jun?

   • They turn into carbon dioxide
   • They have stopped moving
   • Still crossing both ways, evenly
   • They keep piling up inside the cell
5. 5.

   After 15 minutes the counts stay at 6 and 6. In the table, why do the counts stop changing after 15 minutes, Kira?

   • Dots still cross, equally both ways
   • Most dots are now inside
   • The membrane has closed
   • The dots have stopped moving
6. 6.

   Particles still move, but the counts on each side stay even. What do scientists call this state, Luz?

   • Active transport
   • A frozen state
   • Dynamic equilibrium
   • A steep concentration gradient
7. 7.

   As the two sides get closer to even, what happens to the speed of diffusion, Pia?

   • It reverses direction
   • It jumps to a stop
   • It speeds up
   • It slows down
8. 8.

   Why is oxygen usually lower inside a body cell than outside it, Ren?

   • The cell pushes its oxygen back outside
   • Oxygen is made outside cells
   • It uses oxygen to release energy
   • The membrane keeps oxygen out
9. 9.

   Body cells make carbon dioxide as they release energy from food. Which way does that carbon dioxide move, Tala?

   • Into the nucleus
   • Into the cell from outside
   • Out of the cell
   • It stays inside the cell
10. 10.

    Zee draws an arrow for carbon dioxide from 2 dots outside a cell to 9 dots inside. What is wrong with it?

    • It should be a circle
    • Nothing: gases move toward more
    • Carbon dioxide can't cross
    • It should point out, from 9 to 2