sentence2_structure: Pyramid ecosystem<>is used<>to show energy flow through the trophic levels$$$Pyramid ecosystem<>to show<>energy flow
sentence1: Structure and function of ecosystems is also studied including the role of photosynthesis, flow of matter and energy through food chains and trophic levels.
sentence2: Pyramid ecosystem is used to show energy flow through the trophic levels.
question: What is used to show energy flow through the trophic levels?