Lesson Overview Objectives 3.3 Energy Flow in Ecosystems Energy Flow in Ecosystems -Trace the flow of energy through living systems. -Identify the three types of ecological pyramids. Lesson Overview Energy Flow in Ecosystems Food Chains A food chain is a series of steps in which organisms transfer energy by eating and being eaten. Lesson Overview Energy Flow in Ecosystems Food Webs In most ecosystems, feeding relationships are much more complicated than the relationships described in a single chain because many animals eat more than one kind of food. Ecologists call this network of feeding interactions a food web. Lesson Overview Energy Flow in Ecosystems Trophic Levels Each step in a food chain or food web is called a trophic level. Primary producers always make up the first trophic level. Various consumers occupy every other level. Lesson Overview Energy Flow in Ecosystems Ecological Pyramids Ecological pyramids show the relative amount of energy contained within each trophic level. The different types of ecological pyramids are pyramids of energy and pyramids of biomass. Lesson Overview Energy Flow in Ecosystems Pyramids of Energy What limits the number of trophic levels is the amount of energy being passed on. Only ~10% of the energy available within one trophic level is transferred to the next trophic level. Lesson Overview Energy Flow in Ecosystems Pyramids of Biomass The total amount of living tissue within a given trophic level is called its biomass. A pyramid of biomass illustrates the relative amount of living organic matter at each trophic level. Lesson Overview Energy Flow in Ecosystems True or False 1.) The passage of energy from one organism to another according to a particular feeding sequence is called a food chain. _________________________ 2.) In an ecological pyramid, the biomass of living things increases at each higher level. _________________________ 3.) Only about 10 percent of the energy in a trophic level is available to organisms at the next trophic level. _________________________ Lesson Overview Energy Flow in Ecosystems False 1.) The passage of energy from one organism to another according to a particular feeding sequence is called a food chain.True 2.) In an ecological pyramid, the biomass of living things increases at each higher level. False, decreases 3.) Only about 10 percent of the energy in a trophic level is available to organisms at the next trophic level. True
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