Title: Observing Osmosis in Potato Cells
Problem Statement:
1.
How is osmosis shown in potato cells that have soaked in fresh water?
2.
How is osmosis shown in potato cells that have been soaked in very salty water?
Method and Materials:
2 plastic cups (labeled “fresh” and “salt”) water salt spoon
2 similar sized and shaped slices of fresh potato. (aprox. 1cm x 2cm x 6cm)*
Knife to slice potato.
Part 1:
1.
Fill the fresh water cup with distilled water. Set aside.
2.
Fill the salt-water cup with water from the sink.
3.
Add four spoonfuls of salt to the cup and stir.
4.
Stir gently for a full minute.
5.
Obtain your potato slices. The slices should be similar in size and shape but they do not need to be exact.
6.
Record your observations of the potato slices on the results sheet. Include smell, texture, flexibility, color, etc.
7.
Place one slice on your results page in the box labeled “Fresh water: before”.
Carefully trace the size and shape of the slice onto the results page. Use a sharp pencil to trace.
8.
Place the slice in the freshwater cup.
9.
Repeat step seven with the next slice in the “Salt water: before” box.
10.
Briefly stir the salt water again.
11.
Place this slice in the salt-water cup.
12.
Let the lab sit for several minutes while you complete the other class assignment.
Part 2:
1.
Remove the slice in the fresh water.
2.
Record your observations on the results page. Include smell, texture, flexibility, color, etc.
3.
Place the slice on your results page in the box labeled “Fresh water: after”.
Carefully trace the size and shape of the slice onto the results page. Use a sharp pencil to trace. Be sure to trace the same surface you traced before.
4.
Repeat steps 1 – 3 with the slice from the salt water.
5.
Rinse out the cups and clean up any spilled salt and potato pieces. Throw away the potato slices. (Table #1 only: Put your slices back in their cups with the water and put the cups on the shelf below the clock)
6.
Clean up anything else that you see, even if the mess is not from your work.
7.
Ask the teacher if your table is clean enough.

How do you expect the slices to change after soaking in the water? Be specific about each slice.
Fresh Water:
________________________________________________________________________
________________________________________________________________________
Salt Water:
________________________________________________________________________
________________________________________________________________________
:
Observations of the potato slices before they are placed in the water:
Fresh Water:
________________________________________________________________________
________________________________________________________________________
Salt Water:
________________________________________________________________________
________________________________________________________________________
Fresh Water: Before Salt Water: Before
Fresh Water: After Salt Water: After

Observations of the potato slices after they are placed in the water:
Fresh :
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
__________________________________________________________________
Salt:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
____________________________________________________________________
Wait until we go over this lab in class to write your discussion and conclusion.