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Energy Transfer

Mr. Walker Environmental Science Class

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Parts of the Food Web (Objective 5)

  • Producer: An organism that makes its own food. They are also called autotrophs (self-feeders). Producers use energy from the sun or chemicals to produce their food.
  • Consumers: An organism which gets their energy by eating other organisms. They are also called heterotrophs (other-feeders).

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Energy comes from the Sun (Obj 5)

  • The important thing to remember is that almost all organisms get their energy from the sun.
  • Producers get energy directly from the sun.
  • Consumers get energy indirectly from the sun by eating producers or other organisms that eat producers.

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What eats What?

  • Herbivores (plant-eaters) are consumers which eat only producers. Cows and deer etc.
  • Carnivores (flesh-eaters) are consumers which eat only other consumers. Lions and hawks etc.
  • Omnivores (eaters of all) are consumers that eat both producers and animals. Humans, pigs, and bears etc.
  • Decomposers are consumers which get their food by breaking down dead organisms, causing them to rot. Bacteria and fungi etc.

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Use of Energy: Cellular Respiration

  • The process of breaking down food to make chemical energy is called cellular respiration.
  • Cellular respiration breaks down sugar (glucose) into ATP (Adenosine Triphosphate). This ATP carries the energy which our cells use.
  • Our cells use this energy to maintain homeostasis and our daily activities.

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Energy Transfer: Food Chains (Obj 5)

  • A food chain is a sequence in which energy is transferred from one organism to the next as each organism eats another.
  • Grass-> Grasshopper-> Shrew-> Cat-> Hawk

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Energy Transfer in an Ecosystem: Food Webs

  • A food web shows many of the feeding relationships in an ecosystem. It is a series of food chains that are interconnected.
  • Each step in the transfer of energy through an ecosystem is known as a trophic level.

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Energy Loss over each trophic level (Obj 6)

  • Each time energy is transferred, less of it is available to organisms at the next trophic level.
    • Some energy is lost during the process of converting food to energy.
    • Remaining energy to carry out life functions such as producing new cells, regulating body temperature, and moving around.
  • About 90% of energy at each trophic level is used in this way.
  • Only 10% becomes part of the organisms body stored in its molecules. That 10% is available to the next trophic level.