Diffusion across a cell membrane

Grade 7 Science Worksheet

Circle the best answer.

1. 1.

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

   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
   • The cells pump carbon dioxide in
   • Oxygen is made inside the cells
   • Using it keeps the inside count low
3. 3.

   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
   • Still crossing both ways, evenly
   • They keep piling up inside the cell
   • They have stopped moving
4. 4.

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

   • The dots have stopped moving
   • The membrane has closed
   • Most dots are now inside
   • Dots still cross, equally both ways
5. 5.

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

   • A steep concentration gradient
   • A frozen state
   • Dynamic equilibrium
   • Active transport
6. 6.

   A teacher drops food coloring into a glass of warm water and a glass of cold water. In which does it spread faster, Milo?

   • The warm water
   • Neither: coloring can't spread
   • Both at the same speed
   • The cold water
7. 7.

   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?

   • Both at the same speed
   • Cell A
   • Cell B
   • Neither: oxygen stays out
8. 8.

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

   • It jumps to a stop
   • It reverses direction
   • It speeds up
   • It slows down
9. 9.

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

   • Oxygen is made outside cells
   • The cell pushes its oxygen back outside
   • It uses oxygen to release energy
   • The membrane keeps oxygen out
10. 10.

    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 cell from outside
    • Into the nucleus
    • Out of the cell