- Ecosystems transfer energy from the sun to autotrophs (producers), then to organisms that eat producers, and then to organisms that eat those organisms. The amount of energy transferred decreases at each trophic level. - Energy and matter flow through food chains and food webs in ecosystems. Food chains represent single pathways of energy transfer, while food webs illustrate the complex, interconnected feeding relationships. - Pyramids model the distribution and amount of energy and biomass at different trophic levels in an ecosystem, with lower levels containing more than higher levels due to energy lost between levels. Other cycles like the water, carbon, and nitrogen cycles are also crucial to ecosystem structure and function.

1. Ecosystems and the Biosphere