1) An ecosystem is formed by the interaction between a community of living organisms and their non-living physical environment. It includes biotic factors like organisms and abiotic factors like water, soil, and temperature. 2) Ecosystems rely on matter, which is either inorganic or organic, and energy from the sun. Producers use inorganic matter and energy to produce organic matter. Consumers obtain energy by eating producers or other consumers, and decomposers recycle organic matter. 3) Food chains and webs show how energy flows through ecosystems from producers to different trophic levels of consumers. Trophic pyramids illustrate biomass and numbers at each level, with less at higher levels due to