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Title – Lettuce Project
By – Vernon Alexander
Primary Subject – Science
Grade Level – 7-12
Aim:
How do materials move in and out of a cell?
Standards:
1 & 2 Scientific Thinking and Communication
Objective:
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Students will use a lettuce leaf to discover the function of a cell membrane.
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Students will look at a multicellular lettuce and make-believe that it is a one-cell structure.
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Students will try to figure out what would be allowed into a cell by predictions, observations and by explanation.
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Students will do an experiment to show the movement of water into and out of the cell.
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Students will be able to state that the cell membrane lets materials in and out of a cell.
Do Now:
#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?
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#1
Salt Solution
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#2
Water & Food Coloring
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#3
Water & Black Pepper
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Predict:
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Observe:
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Explain:
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Activity:
Data and Observations:
Hypothesis #1:
Hypothesis #2:
Hypothesis #3:
Conclusions:
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?
Going Further:
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.
Discover:
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.
Misconceptions:
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Activity:
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Scientific Principle:
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Movement inside the cell membrane, but not out of the cell.
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#1 – Lettuce placed in a beaker with salt solution.
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Diffusion: Low to high concentration of salt
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Nothing happens.
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#2 – Shriveled lettuce placed into a beaker of water.
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Passive Diffusion: High concentration of water to low concentration of water.
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Everything goes in freely.
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#3 – Lettuce placed in a mixture of black pepper or nutmeg or fine spices without any salt.
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Selective barrier: It lets certain things into a cell, but not others.
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E-Mail
Vernon Alexander
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