Plants and Snails Gizmo Answer Key

Name: Elsie Barajas Date: 11-28-2022 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.) 1. What important gas do we take in when we breathe? Oxygen 2. Why don’t we run out of the important gases that we need to stay alive? Due to the fact that plants produce more oxygen for us to breathe. 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. 1. With the lights set to on, drag a snail into one test tube and a plant into another. Press Play ( each tube? ). After 24 hours, what is the color of One is a blue color, the other is a yellowish hue. 2. 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. A. When the water turns blue, which gas is most common? Oxygen B. When the water turns yellow, which gas is most common? Carbon C. What does it tell you when the water is green? Inside the test tubes, there is an equal mixture of carbon and oxygen. Get the Gizmo ready: Activity A: ● ● ● Gases in and gases out 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? 1. Collect data: Use the Gizmo to learn what gases plants and animals take in and give off. Try it in both light and dark. Record your results below. If you do more than five experiments, write your extra results in your notebook or on separate sheets of paper. What is in the tube Lights: on/off Results Snail and Elodea Sprigs On There are 6.5 ppm of carbon and 5.5 ppm of oxygen in the green water. Snail On There is 10.2 ppm of carbon and 1.8 ppm of oxygen after the snail has perished. Elodea Sprigs On There is 11.6 ppm oxygen and 0.4 ppm carbon and water is blue 2. Analyze: Study your data on gases given off by plants. A. What gas do plants give off in the light? Oxygen B. How about in the dark? less oxygen than carbon 3. Analyze: Study your data on gases given off by animals. A. What gas do animals give off in the light? less oxygen than carbon (about 10.2 ppm carbon) B. How about in the dark? less oxygen than carbon C. How do these results compare to your plant results? For animals, they are essentially the same. 4. Infer: Describe the carbon dioxide-oxygen cycle by completing the sentences below: Animals breathe in Oxygen In sunlight, plants take in Carbon and breathe out Carbon and release Oxygen Get the Gizmo ready: Activity B: Interdependence ● ● ● ● 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? 1. Observe: Put one sprig of Elodea and one snail in a test tube with the lights on. Click Play. A. Does the color of the water in the tube change? No, it continues to be the same shade of green. B. What happens to the O2 and CO2 levels? The oxygen goes to 5.7 ppm and the carbon levels go to 6.3 ppm 2. Predict: Without using the Gizmo, predict what you think will happen to the gas levels in each case listed below. (Leave the Actual result column blank for now.) Tube Prediction Actual result 2 snails, 2 sprigs, lights on Carbon and oxygen will be present in equal amounts, with carbon predominating over oxygen. There is 5.8 ppm carbon and 6.2 ppm oxygen, and both snails are still alive. 1 snail, 2 sprigs, lights on The snail will survive because there will be more oxygen than carbon. The tube is blue, the snail is alive, and there are 0.4 ppm of carbon and 11.6 ppm of oxygen in it. 1 snail, 2 sprigs, lights off I feel like the snail will die and the plants will not make as much oxygen When the snail perishes, there is 11.8 ppm carbon and 0.2 ppm oxygen. 3. Run Gizmo: Now run the Gizmo to test your predictions. Record your findings in the table. 4. Generalize: Describe how plants and animals each contribute to the survival of the other. (This type of cooperative relationship is called interdependence.) Without light, plants cannot produce the oxygen that the snail needs to survive; instead, the plants would continue to exist, but the snail would perish. 5. Challenge: Simulate a 24-hour day (12 hours of light, 12 hours of dark). How many snails and plants do you need to keep a stable environment? Explain any discoveries you make. The identical number of plants and animals would need to be added as in our previous experiment, and the lights would need to be turned on and off at precisely the same time. 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? 1. 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. A. How do the oxygen (O2) and carbon dioxide (CO2) levels change over time? Over time, the amount of oxygen merely keeps increasing until it runs out. B. What is always true about the total amount of O2 and CO2 in the test tube? There will be more oxygen in the air if there are more plants and fewer animals. C. What happens when the CO2 reaches zero? The amount of oxygen is at its peak, and the plant is lovely and healthy. 2. Revise and repeat: Click Reset. Remove the plants. Repeat the experiment with two snails. A. How do the gas levels change? B. What is the total of O2 and CO2? O2 The levels are unchanged. CO2 The levels are unchanged. Oxygen and carbon are both 6.0 ppm. 3. 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? One side never has more than the other because it always has the same number of molecules. In both equations, the number of carbon atoms is six, and the number of hydrogen atoms is twelve. Note how the amount of the number is always split in some way, adding up to the same total and remaining "balanced."