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This lettuce project demonstrates cell diffusion, passive diffusion and selective barrier
9, 10, 11, 12
Title – Lettuce Project
By – Vernon Alexander
Primary Subject – Science
Grade Level – 9-12
- How do materials move in and out of a cell?
- 1 & 2 Scientific Thinking and Communication
- Students will use a lettuce leaf to discover the function of a cell membrane.
- Students will look at a multicellular lettuce and make-believe that it is a one-cell structure.
- Students will try to figure out what would be allowed into a cell by predictions, observations and by explanation.
- Students will do an experiment to show the movement of water into and out of the cell.
- Students will be able to state that the cell membrane lets materials in and out of a cell.
- #1 Predict what would happen if you placed a piece of lettuce into a salt solution?
- #2 Predict what would happen if you placed a piece of lettuce into food coloring?
- #3 Predict what would happen if you placed a piece of lettuce into a mixture of water and black pepper?
Water & Food Coloring
Water & Black Pepper
- Data and Observations:
- Hypothesis #1:
- Hypothesis #2:
- Hypothesis #3:
- 1. Explain what happened to the lettuce leaves after being placed into various beakers or cups.
- 2. What can go into and out of a lettuce leaf?
- 3. What happened when a lettuce leaf was placed in a beaker containing various spices, black pepper and/or nutmeg?
- 4. Using a lettuce leaf to represent a cell membrane, can everything go into a cell?
- 5. A leaf is a collection of many cells. What did you observe when you added food coloring?
- Will changing the amount of salt in the solution affect the amount of water in the lettuce leaf? Form a hypothesis to this question. Design an experiment to test your hypothesis.
- When working on the experiment, you used salt on the lettuce leaf. Explain how the preservation of food can be possible (salt-fish, pork, meat products). Also, use reference materials to investigate how we used diffusion and selective barrier in our experiment with the lettuce leaf.
|Movement inside the cell membrane, but not out of the cell.||#1 – Lettuce placed in a beaker with salt solution.||Diffusion: Low to high concentration of salt|
|Nothing happens.||#2 – Shriveled lettuce placed into a beaker of water.||Passive Diffusion: High concentration of water to low concentration of water.|
|Everything goes in freely.||#3 – Lettuce placed in a mixture of black pepper or nutmeg or fine spices without any salt.||Selective barrier: It lets certain things into a cell, but not others.|
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