#601 - Plants and Snails Oh MY! - Jennifer Kaltenbach | Library

                Student Exploration: Plants and Snails
  
Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes.

Vocabulary: aerobic respiration, bromothymol blue (BTB), carbon dioxide-oxygen cycle, indicator, interdependence, photosynthesis

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

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What important gas do we take in when we breathe?

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Why don’t we run out of the important gases that we need to stay alive?

Gizmo Warm-up
In the Plants and Snails Gizmo, each of the test tubes contains water and a small amount of bromothymol blue (BTB). BTB is a chemical indicator. An indicator changes color when the chemicals in the water change.

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With the lights set to on, drag a snail into one test tube and a plant into another. Press Play. After 24 hours, what is the color of each tube?

Select Show oxygen and CO2 values. Place the O2/CO2 probe in each tube. The probe shows the levels of two gases, oxygen (O2) and carbon dioxide (CO2), in the tubes. We call these amounts the gas levels.

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When the water turns blue, which gas is most common?

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When the water turns yellow, which gas is most common?

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What does it tell you when the water is green?

Activity A:     Gases in and gases out
Get the Gizmo ready:
Click Reset 
Clear all of the test tubes.
Turn on Show oxygen and CO2 values.

Question: What gases do plants and animals take in and what do they give off?

Collect data: Use the Gizmo to learn what gases plants and animals take in and give off. Try it in both light and dark. 

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Analyze: Study your data on gases given off by plants. What gas do plants give off in the light?

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Analyze: Study your data on gases given off by plants. What gas do plants give off in the dark?

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Analyze: Study your data on gases given off by animals. What gas do animals give off in the light?

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Analyze: Study your data on gases given off by animals. What gas do animals give off in the dark?

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How do these results compare to your plant results? (especially plants in the dark)

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Infer: Describe the carbon dioxide-oxygen cycle by completing the sentences below: Some will be used more than once

oxygen (O2)
carbon dioxide (CO2)

Animals breathe in
Animals breathe out
In sunlight, plants take in
and release

Activity B: Interdependence

Get the Gizmo ready:
Click Reset.
Clear all of the test tubes.
Turn the light switch to on.
Check Show oxygen and CO2 values.

Question: How do plants and animals depend on each other?
Observe: Put one sprig of Elodea and one snail in a test tube with the lights on. Click Play.

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Does the color of the water in the tube change?

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What happens to the O2 and CO2 levels?

Think about ...
What would happen if 
you had two snails, and two sprigs with the lights on?
you had two snails and two springs with the lights off?

Run a few different scenarios and record your findings in your note book

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Generalize: Describe how plants and animals each contribute to the survival of the other. Be specific.

Activity C: The carbon-oxygen balance
Get the Gizmo ready:
Click Reset.
Clear all of the test tubes.
Turn the light switch to on.
Check Show oxygen and CO2 values.

Question: How are the amounts of oxygen and carbon dioxide related to each other?
Observe: Put two Elodea sprigs into a test tube. Put the O2/CO2 probe into the tube with the Elodea. Click Play. As the Gizmo runs, Pause  it a few times.

1

How do the oxygen (O2) and carbon dioxide (CO2) levels change over time?

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What is always true about the total amount of O2 and CO2 in the test tube?

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What happens when the CO2 reaches zero?

Revise and repeat: Click Reset and run the experiment again, this time with the lights off.

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How do the gas levels change?

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What is the total of O2 and CO2?

Revise and repeat: Click Reset. Remove the plants. Repeat the experiment with two snails. Leave the lights OFF and just remove the plants.

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How do the gas levels change?

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What is the total of O2 and CO2?

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Challenge: In the process of photosynthesis, plants use carbon dioxide (CO2), water (H2O), and light energy to produce a sugar (C6H12O6) and oxygen (O2). In the process of aerobic respiration, animals and plants release energy from sugar and oxygen and produce carbon dioxide and water. The chemical equations that describe these reactions look like this:
6CO2 + 6H2O + light 🡪 C6H12O6 + 6O2 C6H12O6 + 6O2 🡪 6CO2 + 6H2O + energy
How do these equations explain why the total amount of O2 and CO2 remains the same?