Diffusion across a cell membrane

Grade 7 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   Cell arrow diagram (model data, not to scale). No arrows are drawn yet. Dots can cross both ways. When the two sides even out, how many oxygen dots will each side have, Ari?

   • 7 on each side
   • 8 on each side
   • 0 outside and 16 inside
   • 12 on each side
2. 2.

   model data, not to scale. Dots can cross both ways. When the two sides even out, how many oxygen dots will each side have, Bo?

   • 9 on each side
   • 0 outside and 22 inside
   • 11 on each side
   • 14 on each side
3. 3.

   Outside a cell, oxygen stays at 10 dots. The cell starts using oxygen faster, and its inside count drops from 4 to 1. What happens next, Jun?

   • Oxygen stops moving in
   • Oxygen moves in faster
   • Oxygen starts moving out
   • The cell must push it in
4. 4.

   model data, not to scale. No arrows are drawn yet. At night a leaf cell makes no sugar but keeps using oxygen to release energy. Which way does each gas move, Kira?

   • Neither moves at night
   • Oxygen in, carbon dioxide out
   • Oxygen out, carbon dioxide in
   • Both gases move out

5. Read this first

   Use this

   Cell arrow diagram (model data, not to scale). The cell membrane is between them, and both boxes are the same size. No arrows are drawn yet.

6. 5.

   Outside oxygen falls until it matches the inside: 5 dots and 5 dots. What happens to oxygen now, Luz?

   • It turns into water
   • It keeps crossing, with no overall change
   • It rushes out of the cell
   • Its particles stop moving

7. Model data

   trial	dots on side 1 at the start	dots on side 2 at the start	dots crossing in the first minute
   trial A	20	0	6
   trial B	12	8	1

8. 6.

   Which claim does the table support, Noah?

   • A smaller difference makes diffusion faster
   • A bigger difference makes diffusion faster
   • The difference makes no change
   • Dots cross just when a side is empty
9. 7.

   A teacher compares a light gas and a heavy gas at the same temperature. Which spreads faster, Pia?

   • The heavier gas
   • The lighter gas
   • Both at the same speed
   • Neither gas spreads
10. 8.

    Ren says diffusion stops when the sides are even because the particles stop moving. Agree or disagree?

    • Agree: the membrane locks them
    • Disagree: they pile up on one side
    • Agree: even sides mean still particles
    • Disagree: they keep moving both ways
11. 9.

    Tala says a cell spends energy to pull oxygen in by diffusion. Agree or disagree?

    • Agree: the membrane pumps oxygen
    • Agree: oxygen can't cross without a push
    • Disagree: diffusion needs no energy
    • Disagree: oxygen can't cross a membrane
12. 10.

    Zee says oxygen moves into a cell because the cell needs it. Agree or disagree?

    • Agree: oxygen knows where to go
    • Disagree: it moves from fewer to more
    • Disagree: it moves from more to fewer
    • Agree: the cell spends energy to call it in