Topic Summary
Topic 2.2, “Energy and Biomass in Ecosystems,” examines the flow and transformation of energy and matter through ecosystems. It highlights how energy enters ecosystems via sunlight, is transformed by photosynthesis, and moves through food chains and webs across trophic levels. The topic explores key principles such as the first and second laws of thermodynamics, focusing on energy transformation, loss as heat, and entropy. Students learn to analyse ecological efficiency, trophic relationships, and the impacts of pollutants like bioaccumulation and biomagnification. It also discusses human impacts on these flows and emphasises the importance of sustainable management
Lessons
Lesson 1: Photosynthesis, respiration and the laws of thermodynamics
Lesson 2: Food webs and the second law of thermodynamics
Lesson 3: Productivity and ecological pyramids
Primary productivity explained
Lesson 4: Human impacts on food webs (pollution and biomagnification)
Lesson 5: Biomass and energy in organic material
Lesson 6 (HL): Productivity
Theory of Knowledge
- To what extent does the use of models, such as energy pyramids, simplify or distort the reality of ecosystems?
- How does the concept of productivity in ecosystems illustrate the limitations of quantitative data in understanding ecological complexity?