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
   • 0 outside and 16 inside
   • 12 on each side
   • 8 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?

   • 0 outside and 22 inside
   • 11 on each side
   • 9 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?

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

4. 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.

5. 4.

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

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

6. Table (model data) from a teacher's demonstration, dots on side 2 of a membrane, starting with 16 dots on side 1

   time (minutes)	warm trial	cold trial
   0	0	0
   5	6	3
   10	8	5

7. 5.

   Each trial evens out at 8 dots on side 2. Which trial evened out first, Milo?

   • Neither by 10 minutes
   • The cold trial
   • Both at 5 minutes
   • The warm trial

8. 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

9. 6.

   Which claim does the table support, Noah?

   • Dots cross just when a side is empty
   • The difference makes no change
   • A smaller difference makes diffusion faster
   • A bigger difference makes diffusion faster
10. 7.

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

    • The heavier gas
    • Both at the same speed
    • The lighter gas
    • Neither gas spreads
11. 8.

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

    • Agree: the membrane locks them
    • Agree: even sides mean still particles
    • Disagree: they pile up on one side
    • Disagree: they keep moving both ways
12. 9.

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

    • Disagree: diffusion needs no energy
    • Agree: oxygen can't cross without a push
    • Disagree: oxygen can't cross a membrane
    • Agree: the membrane pumps oxygen
13. 10.

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

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