Name:______

Class: ______

Date: ______

Background Information:

You have learned that osmosis and diffusion are ways in which the cell moves materials across the cell membrane. Osmosis is the diffusion of water across the cell membrane. Neither of these processes requires energy (passive transport). If the cell takes in a lot of water, it becomes rigid and stiff. When cells lose water, the cell becomes shriveled. This happens when a plant wilts, or when a grape turns into a raisin.

Question: How will salt water and tap water affect a potato?

Concepts:

Osmosis:______

Passive Transport:______

Rigid and Stiff Cell:______

Shriveled or Wilting Cell:______

Materials:

Salt water

Tap water

3cups

Gummy Bears

Potato pieces (3)

Ruler

Paper Towel

Gummy Bears

Procedure:

  1. Label two cups A =TAP and B =SALT.
  2. Fill cup A halfway with cool tap water.
  3. Fill cup B half way withSALT water.
  4. Obtain 3 pieces of potato that are about the same size.
  5. Using a ruler, measure the length, in millimeters, of all 3 pieces of potato and record in the DATA chart below. (For example, 10 mm)
  6. Place potato #1 in a damp paper towel.
  7. Place potato #2 into cup A.
  8. Place potato #3 into cup B.
  9. Let the pieces of potato sit for 15 minutes. Record start time so you know when to take potatoes out of their “treatments.” Start Time ______
  10. While you are waiting, start PART 2 (Gummy Bear section).
  11. After the 15 minutes is up, remove the potatoes from their treatments and re-measure their lengths and make observations about their appearance.
  12. Throw away the potato pieces, return all equipment to their original condition and position.

Data:

Part 1: POTATO

Potato / Beginning length (mm) / After length (mm) / Change (mm) / Description of texture/appearance
1
2
3

Conclusion:Use complete sentences.

1)Explain the measurement changes you observed in terms of osmosis.

______

2)Which potato was the experimental control? What was its purpose? ______

3)Describe the appearance or texture of the potato soaked in tap water, compared to the control. How do you explain this? ______

4)Describe the appearance or texture of the potato soaked in beaker B, compared to the control. How do you explain this? ______

PART 2: OSMOSIS GUMMY BEARS

Hypotheses:

  1. If I place a Gummy Bear in tap water, then the size of the bears will:

( increase,decrease, remain the same ). Circle your answer.

  1. If I place a Gummy Bear in salt water, then the size of the bear will:

( increase, decrease, remain the same ). Circle your answer.

Procedure:

1.Obtain 1 plastic cup, 1 Gummy Bear, and 1 ruler.

2.Label the cup with your name and class. You may name your bear if you want 

3.Fill ¾ of the cup with water.

4.Measure your bear (in mm) from top to bottom (length) and from side to side (width) and from front to back (height). Record the millimeters in the DATA table below.

5.Let your bear swim in the cup overnight.

6.Place the cup on the back tables away from direct sunlight.Let them sit overnight. We will measure them tomorrow.

Our Gummy Bear “______” (nickname)

DATA:

Volume = Length x Width x Height

Length (mm) / Width (mm) / Height (mm) / Volume (mm3)
example / 5 mm / 2mm / 1 mm / 10 mm3
Before Water
After Water