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?

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

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

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

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

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

   • Active transport
   • Dynamic equilibrium
   • A steep concentration gradient
   • A frozen state
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?

   • Both at the same speed
   • Neither: coloring can't spread
   • The warm water
   • 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 B
   • Cell A
   • Neither: oxygen stays out
8. 8.

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

   • The membrane keeps oxygen out
   • It uses oxygen to release energy
   • Oxygen is made outside cells
   • The cell pushes its oxygen back outside
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
   • It stays inside the cell
   • 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?

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