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?

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

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

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

5. Read this first

   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

6. 5.

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

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

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

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

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

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

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

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

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

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

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