In this activity, students analyze the production and utilization of organic molecules in ecosystems. Students use pre-made cards to construct a food web for Yellowstone National Park, including producers, primary consumers, secondary consumers, decomposers, and trophic omnivores. Then, students analyze a trophic cascade that resulted when wolves were reintroduced to Yellowstone National Park.
Students learn how organic molecules move and are transformed in ecosystems as a result of the trophic relationships in food webs, photosynthesis, cellular respiration, and biosynthesis. This provides the basis for understanding carbon cycles and energy flow through ecosystems. In the final section, students use these concepts and quantitative reasoning to understand trophic pyramids.