1. Ecosystems Unit Activity 3.3 Supplement
Carbon: Transformations in Matter and Energy
Environmental Literacy Project Michigan State University
Ecosystems Unit Activity 3.3 Supplement
Image Credit: Craig Douglas, Michigan State University

2. How can we explain the organic matter pyramid by tracing carbon atoms through the ecosystem?
Let's follow 500 carbon atoms through the ecosystem.
The organic matter pyramid: Comparing the organic matter of producers, herbivores, and carnivores.
Carnivores 1 10
In these slides we are counting individual carbon atoms, but real ecosystems have far too many carbon atoms to count.  For example, the organic matter of a small meadow contains more than 10,000,000,000,000,000,000,000,000,000 carbon atoms!
Note: The pathways of carbon atoms are the same in all ecosystems, but the numbers of atoms are different.
Atmosphere
Herbivores
Introduce the organic matter pyramid animation.
Tell students that they will follow a computer simulation that tracks 500 carbon atoms through an ecosystem to evaluate their predictions about how carbon-transforming processes impact organic carbon pool sizes.
Show Slide 2 to begin the Presentation. Be sure to show the Presentation in “presentation mode” so the animations are visible. Click one time to advance the animation so students can see the “organic matter pyramid,” which shows one hundred carbon atoms in the producer pool, ten carbon atoms in the herbivore pool, and one carbon atom in the carnivore pool. Remind students that these numbers are used to show relative size.
Click a second time so that the arrows appear and the molecules start moving from pool to pool.
Image Credit: Craig Douglas, Michigan State University
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Soil Carbon
Producers

3. 100 What happens to carbon atoms in producers? - Photosynthesis
Carnivores
- Cellular Respiration/Biosynthesis
200 carbon atoms go back to the atmosphere when plants use the sugar for cellular respiration.
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- Being Eaten/Death
Note: The pathways of carbon atoms are the same in all ecosystems, but the numbers of atoms are different.
Atmosphere
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Herbivores
500 carbon atoms become part of sugar molecules through photosynthesis.
100 carbon atoms go to herbivores when they eat plants.
Have students watch the animations.
Go through the animations as a class.
Display Slide 3. Click through the animations until all of the processes moving carbon into and out of the Producer pool are complete.
Image Credit: Craig Douglas, Michigan State University
300 carbon atoms become part of the plant through biosynthesis.
100 carbon atoms stay in the living plants.
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100 carbon atoms go to the soil when plants or leaves die.
Soil Carbon
Producers

4. 100 10 What happens to carbon atoms in herbivores?
Note: The pathways of carbon atoms are the same in all ecosystems, but the numbers of atoms are different.
What happens to carbon atoms in herbivores?
What happens to carbon atoms in producers?
15 carbon atoms go to carnivores when they eat herbivores. 10 12 11 13 14 15 4 2 3 5 7 1 9 6 8
- Undigested food/Defecation
Carnivores
- Cellular Respiration/Biosynthesis
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- Being Eaten/Death
34 carbon atoms become part of the herbivore through biosynthesis.
Atmosphere
50 carbon atoms go back to the atmosphere when herbivores use the food for cellular respiration.
10 carbon atoms stay in the living herbivores.
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Herbivores
9 carbon atoms go to the soil when herbivores die.
16 carbon atoms go to the soil when herbivores defecate.
100 carbon atoms go to herbivores when they eat plants.
Have students watch the animations (cont.)
Click through the animations until all of the processes moving carbon into and out of the Producer pool are complete.
Repeat this process with Slides 4-7 with the herbivore, carnivore, soil carbon, and atmosphere pools. Note: Students may come up with ideas that are not represented in the ecosystem model. For example, CO2 molecules can be dissolved into the oceans. However, because we do not have an ocean pool in this model, the ocean pool is not discussed. This might be an appropriate time to discuss the fact that all models have limitations. Congratulate students for thinking of ways carbon atoms can move that were not represented in the model!
Image Credit: Craig Douglas, Michigan State University
100 carbon atoms stay in the living plants.
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100 carbon atoms go to the soil when plants die.
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Producers

5. 100 1 10 What happens to carbon atoms in carnivores?
8 carbon atoms go back to the atmosphere when carnivores use the food for cellular respiration.
Note: The pathways of carbon atoms are the same in all ecosystems, but the numbers of atoms are different.
What happens to carbon atoms in carnivores?
What happens to carbon atoms in herbivores?
1 carbon atom stays in the living carnivores.
15 carbon atoms go to carnivores when they eat herbivores. 13 14 11 12 10 15 6 8 9 7 4 2 3 5 1
- Undigested food/Defecation
3 carbon atoms become part of carnivores through biosynthesis.
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- Cellular Respiration/Biosynthesis 10
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- Death
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10 carbon atoms stay in the living herbivores. 10
4 carbon atoms go to the soil when carnivores defecate.
2 carbon atoms go to the soil when carnivores die.
Herbivores
9 carbon atoms go to the soil when herbivores die.
Have students watch the animations (cont.)
Click through the animations until all of the processes moving carbon into and out of the Producer pool are complete.
Repeat this process with Slides 4-7 with the herbivore, carnivore, soil carbon, and atmosphere pools. Note: Students may come up with ideas that are not represented in the ecosystem model. For example, CO2 molecules can be dissolved into the oceans. However, because we do not have an ocean pool in this model, the ocean pool is not discussed. This might be an appropriate time to discuss the fact that all models have limitations. Congratulate students for thinking of ways carbon atoms can move that were not represented in the model!
Image Credit: Craig Douglas, Michigan State University
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Producers

6. 100 1 10 What happens to carbon atoms in carnivores?
Note: The pathways of carbon atoms are the same in all ecosystems, but the numbers of atoms are different.
What happens to carbon atoms in carnivores?
What happens to carbon atoms in the soil?
1 carbon atom stays in the living carnivores. 1
- Cellular Respiration/Biosynthesis
Carnivores 1 10
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Atmosphere
66 carbon atoms go back to the atmosphere when decomposers use the soil carbon for cellular respiration. 10
6 carbon atoms go to the soil when carnivores die.
Herbivores
Have students watch the animations (cont.)
Click through the animations until all of the processes moving carbon into and out of the Producer pool are complete.
Repeat this process with Slides 4-7 with the herbivore, carnivore, soil carbon, and atmosphere pools. Note: Students may come up with ideas that are not represented in the ecosystem model. For example, CO2 molecules can be dissolved into the oceans. However, because we do not have an ocean pool in this model, the ocean pool is not discussed. This might be an appropriate time to discuss the fact that all models have limitations. Congratulate students for thinking of ways carbon atoms can move that were not represented in the model!
Image Credit: Craig Douglas, Michigan State University
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65 carbon atoms stay in the soil.
Producers

7. Note: The pathways of carbon atoms are the same in all ecosystems, but the numbers of atoms are different.
How can we explain the organic matter pyramid by tracing carbon atoms through the ecosystem?
Carnivores 1
Plants, animals, and decomposers create the organic matter pyramid through their carbon-transforming processes--when they photosynthesize, eat, grow, live, and die. 10
500
Atmosphere
Herbivores
Have students watch the animations (cont.)
Click through the animations until all of the processes moving carbon into and out of the Producer pool are complete.
Repeat this process with Slides 4-7 with the herbivore, carnivore, soil carbon, and atmosphere pools. Note: Students may come up with ideas that are not represented in the ecosystem model. For example, CO2 molecules can be dissolved into the oceans. However, because we do not have an ocean pool in this model, the ocean pool is not discussed. This might be an appropriate time to discuss the fact that all models have limitations. Congratulate students for thinking of ways carbon atoms can move that were not represented in the model!
Have students share reflections on the animations.
By the end of the presentation, there will be 100 atoms in the producers, 10 atoms in the herbivore pool, and 1 in the carnivore pool, and students should begin to have an answer for why carnivores need so much grass to support them.
At this point, you may want to watch the animation again, so students can see the carbon atoms moving through the pools without pausing to examine their predictions.
Image Credit: Craig Douglas, Michigan State University
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Soil Carbon
Producers