Energy Flow in Ecosystems Life depends on the sun. We get all of our energy, directly or indirectly from the sun. The process called photosynthesis uses sunlight to make sugar molecules.

Life depends on the Sun Solar energy drives a series of chemical reactions that require carbon dioxide and water to produce carbohydrates.

Life depends on the Sun

What Eats What

Cellular Respiration: Burning the Fuel The process of breaking down food to yield energy is called cellular respiration. This is the reverse of photosynthesis.

Energy Transfer Each time one organism eats another organism, a transfer of energy occurs. We can trace the transfer of energy as it travels through the ecosystem by studying the food chains, food webs, and trophic levels.

Food Chain A food chain is a sequence in which energy is transferred from one organism to the next as each organism eats another.

Food Web Is the many feeding relationships that are possible in an ecosystem.

Food Chain vs. Food Web FOOD CHAIN (just one path of energy) FOOD WEB (everything is connected!)

Trophic Levels Each step through which energy is transferred in a food chain is known as a trophic level. Each time energy is transferred from one organism to another some of the energy is lost as heat and less energy is available to the next level.

Energy Pyramid