Cell Transport: When It Comes to Cells, Small Is Good

Materials

Potato cube with a 1 cm³ volume

Potato cube with a 3 cm³ volume

Small beaker of Lugol's solution or iodine

Plastic knife

Forceps

Paper towel

Activity

1. Place both cubes of potato in the beaker of Lugol's solution. Potatoes contain starch, which takes on a blue-black color in Lugol's solution.
2. Leave the potato cubes in the solution for four minutes.
3. Use forceps to remove each of the cubes and place them on a paper towel on a table.
4. Both cubes should have a blue-black coloration. To see how far the solution has traveled into the potato cubes, use the knife to cut the cubes open and look inside.

Follow-Up Questions

1. In which cube did the Lugol's solution (or iodine) get closer to the center?
2. The cubes represent cells. Would nutrients be more likely to diffuse to all parts of a small cell or a large cell?
3. Oxygen diffuses into cells in a similar way to how Lugol's solution diffuses into potato cubes. Would you expect a large cell to be able to supply oxygen to all of its parts?

Answers

1. Potato cube with a 1 cm3 volume.
2. Small cell.
3. No.

Extension

Try this activity with potato cubes of different sizes. Allow more time for soaking in Lugol's solution. Do you get similar results?