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

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

   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 carbon dioxide dots will each side have, Esme?

   • 0 inside and 24 outside
   • 16 on each side
   • 10 on each side
   • 12 on each side
4. 4.

   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 moves in faster
   • Oxygen stops moving in
   • The cell must push it in
   • Oxygen starts moving out
5. 5.

   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?

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

6. 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

7. 6.

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

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

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. 7.

   Which claim does the table support, Noah?

   • A bigger difference makes diffusion faster
   • Dots cross just when a side is empty
   • A smaller difference makes diffusion faster
   • The difference makes no change
10. 8.

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

    • Neither gas spreads
    • The heavier gas
    • Both at the same speed
    • The lighter gas
11. 9.

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

    • Disagree: they pile up on one side
    • Disagree: they keep moving both ways
    • Agree: the membrane locks them
    • Agree: even sides mean still particles
12. 10.

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

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