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
   • Both gases move in
   • Oxygen in, carbon dioxide out
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?

   • Neither moves in sunlight
   • Both gases move in
   • 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?

   • The cells pull oxygen in with energy
   • Oxygen is made inside the cells
   • 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 have stopped moving
   • Still crossing both ways, evenly
   • They keep piling up inside the cell
   • They turn into carbon dioxide
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?

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

   Cell A has 20 oxygen dots outside and 2 inside. Cell B has 8 outside and 6 inside. Into which cell does oxygen move faster, Noah?

   • Cell B
   • Cell A
   • Both at the same speed
   • Neither: oxygen stays out
7. 7.

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

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

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

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