1. How do the materials needed for life get in and out of cells?
Lab: Cell Transport
Essential Question:
How do the materials needed for life get in and out of cells?

2. Pure H2O H2O + salt Corn syrup
Explain in terms of diffusion what happened to each egg….
Pure H2O
H2O + salt
Corn syrup

3. Explain in terms of diffusion what happened to each egg….
80% water
80% water
80% water
Pure H2O
(100% water)
H2O + salt
(80% water
20% salt)
Corn syrup
(55% water
45% sugar)
Hypotonic
Isotonic
Hypertonic
Water moved in & out of egg at same rate,
So egg stayed same size
Water diffused into egg,
Making it swell (get bigger)
Water diffused out of egg,
Making it shrink

4. What’s the difference between osmosis and diffusion?
Diffusion = movement of molecules from area of high concentration to low.
Osmosis = diffusion of water molecules across a membrane.
Red food coloring diffuses through a glass of water
Water moves by osmosis from left to right

8. Starch solution in bag turned blue-gray.
1. Based on your observations, which substance passed through the dialysis tubing, the iodine or the starch? How do you know this?
Iodine.
Starch solution in bag turned blue-gray.

9. Iodine molecules diffused into bag through tiny holes in membrane.
2. How do you think this substance got through the tubing (assuming the ends were sealed)?
Iodine molecules diffused into bag through tiny holes in membrane.

10. Movement of molecules from area of high concentration to low
3. Define diffusion.
Movement of molecules from area of high concentration to low

11. Iodine molecules diffused into baggie.
4. Sketch the beaker and baggie in the space below. Draw arrows to explain how diffusion occurred in this experiment.
Iodine molecules diffused into baggie.

12. Water outside baggie turned orange.
5. Based on your observations, which substance passed through the dialysis tubing, the sugar or the Benedict’s solution? How do you know this?
Sugar.
Water outside baggie turned orange.

13. Sugar molecules diffused out of the baggie.
6. Sketch the beaker and baggie in the space below. Draw arrows to explain how diffusion occurred in this part of the experiment.
Sugar molecules diffused out of the baggie.

14. 7. How would differences in size of starch and sugar molecules explain the different results observed in parts A and B?
Starch molecules too big to go through holes in membrane.
Sugar molecules small enough to go through.
starch
Glucose
(sugar)

15. Cell membrane

16. 8. How does this experiment show one important way that life depends on water?
Water is needed to dissolve materials needed for life – oxygen, nutrients, etc. – so they can be transported in & out of cells, and around body.