Names ______________________________ ______________________________
Passive Transport Lab – Diffusion & Osmosis
DAY 1: (your teacher will assign each group a number) Group # ________
Part 1 – Diffusion
1.
Obtain a piece of dialysis tubing.
2.
Tie a knot at one end of the tubing and reinforce the knot with dental floss (tie knot).
3.
Place the starch solution in the dialysis tubing.
4.
Tie a knot in the second end of the tubing and again reinforce the end with dental floss.
5.
Have your teacher check your knots to see if they are done correctly.
6.
Rinse the ends of your dialysis tubing in the “rinse bucket” and then place the tubing in the water-iodine solution container.
Water-Iodine Solution in container
Starch Solution in dialysis tubing
7.
What color is the starch solution in the dialysis tubing? ________________________
8.
What color is the water/iodine solution? ____________________________________
9.
If the dialysis tubing that you used for this lab behaves like a selectively permeable cell membrane, what do you think will be able to pass through the tubing (water, iodine, and/or starch)? ________________________________________________________
Part II – Osmosis: Gummy Bears
1.
Obtain one gummy bear and a ruler.
2.
Measure and record the length and width of the gummy bear, in centimeters (to the nearest 1/10). Length = __________ cm Width = __________ cm
3.
Place the gummy bear in the container designated by your teacher.
Part III – Osmosis: Potatoes
1.
Obtain two potato slices.
2.
Record your observations about the texture of the potato slices. Are they hard, soft, flexible, rigid, etc.?
_____________________________________________________________________
_____________________________________________________________________
3.
Place a “nick” in the edge of your potatoes. You should make as many nicks as your group number (i.e. if your group # is 4, you put 4 nicks in the potato).
4.
Label each potato A or B and then weigh each potato and record their masses. mass of Potato A __________ g mass of Potato B __________ g
5.
Place the potato slices in the containers designated by your teacher. Each one goes in a different container (labeled A or B).

DAY 2:
Part 1 – Diffusion
1.
What color is the starch solution in the dialysis tubing? ___________________________
2.
What color is the water/iodine solution (in the container)? _________________________
3.
What passed through the dialysis tubing? How do you know?
_____________________________________________________________________
_____________________________________________________________________
Part 2 – Osmosis: Gummy Bears
1.
Measure and record the length and width of the gummy bear in centimeters (to the nearest 1/10). Length = __________ cm Width = __________ cm
2.
What happened to the gummy bear? _______________________________________
_____________________________________________________________________
3.
What type of solution was the gummy bear placed in (hypertonic, hypotonic, or isotonic)? ____________________________________________________________
4.
Draw what happened to the gummy bear below. Show the overall movement of water
(going in or out of gummy “cell”).
Part 3 – Osmosis: Potatoes
1.
Retrieve each of your potatoes (A and B).
2.
Lightly dry off each potato with a paper towel and then weigh each one and record their masses. mass of Potato A = __________ g mass of Potato B = __________ g
3.
Record your observations about the texture of the potato slice that was in the container labeled A. Is it hard, soft, flexible, rigid, etc.?
___________________________________________________________________
4.
Record your observations about the texture of the potato slice that was in the container labeled B. Is it hard, soft, flexible, rigid, etc.?
_____________________________________________________________________
5.
What type of solution was potato A in? _____________________________________
6.
What type of solution was potato B in? _____________________________________
7.
Draw what happened to each potato below. Use arrows to show the net movement of water.
A B