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Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of three Science Objects in the Flow of Matter and Energy in Ecosystems SciPack. It explores how energy flows through an ecosystem in one direction, from photosynthetic organisms to herbivores to omnivores and carnivores and decomposers. As the energy flows, less and less energy isavailable to support life.
Plants capture the sun's energy and use it to synthesize complex, energy-rich molecules (chiefly sugars) from molecules of carbon dioxide and water. Because plants and other photosynthetic organisms use energy from the sun and inorganic molecules from the environment to produce organic molecules needed for life, they are called producers. The organisms that consume the producers (called consumers) derive energy and materials from breaking down the producers’ molecules, use them to synthesize their own structures and then may be consumed by other organisms. Decomposers (organisms that break down dead producers and consumers and organic waste) obtain the energy they need to live from chemical bonds of the dead and waste-matter. The energy is transferred both to the decomposer (for growth and development) and to the ecosystem (as heat energy). Food webs and energy pyramids are models or representations that can be used to track the flow of energy in the ecosystem. Food webs detail the flow of energy through the populations in the ecosystems whereas the pyramid model quantifies the flow of energy through various levels in an ecosystem. Unlike matter, as energy flows through an ecosystem in one direction, from photosynthetic organisms to herbivores to omnivores and carnivores and decomposers, less and less energy becomes available to support life. This loss of useable energy occurs because each energy transfer results in the dissipation of some energy into the environment as heat. Continual input of energy from sunlight is necessary to keep ecosystems organized and functioning.
- Explain how a food web describes the flow of energy within an ecosystem
- Explain the role that the amount of sunlight available to an ecosystem plays on defining the size and types of populations within an ecosystem
- Use the characteristics of energy transfer (from one population to another) to explain the structure of an energy pyramid for organisms living in a community
- Explain why, if energy is conserved in the interaction of consumers and producers, there is less energy at the consumer level compared to the producer level in an energy pyramid
- Explain why a vegetarian diet for humans requires less energy to produce the food needed than a diet that includes meat and fish does
- Compare the flow of matter with the flow of energy among organisms and between organisms and their environment in an ecosystem