Energy in ecosystem new


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Energy in ecosystem new

  1. 1. Food Chain and Energy Transfer
  2. 2. Food Chain Producers Primary Consumers Secondary Consumers Tertiary Consumers
  3. 3. Terminology - Ecosystem <ul><li>Herbivore </li></ul><ul><ul><li>animals that eat only plants. </li></ul></ul><ul><li>Carnivore </li></ul><ul><ul><li>animals that eat only animals. </li></ul></ul><ul><li>Omnivore </li></ul><ul><ul><li>animals that eat plants and animals. </li></ul></ul><ul><li>Top Carnivore </li></ul><ul><ul><li>animals not eaten by anything else. </li></ul></ul><ul><li>Decomposer </li></ul><ul><ul><li>organisms that live on dead material. </li></ul></ul><ul><li>Trophic Levels </li></ul><ul><ul><li>each step along a food chain. </li></ul></ul>
  4. 4. Primary Production
  5. 5. Primary production <ul><li>Primary production </li></ul><ul><ul><li>is the production of organic compounds from atmospheric or aquatic carbon dioxide, mainly through the process of photosynthesis. </li></ul></ul><ul><li>Gross primary production </li></ul><ul><ul><li>is the total amount of energy fixed by primary producers in an ecosystem. </li></ul></ul><ul><li>Net primary production. </li></ul><ul><ul><li>Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues. </li></ul></ul><ul><ul><li>The remaining fixed energy is referred to as net primary production. </li></ul></ul>
  6. 6. Primary production
  7. 7. Energy Flow <ul><li>Plants convert a small portion of light energy into glucose (biomass) </li></ul><ul><li>The energy works its way through the food chain. </li></ul><ul><li>Energy transferred from one trophic level to the next is about 10%. </li></ul><ul><li>This means that at each step in the food chain, as much as 90% of energy is lost. </li></ul>
  8. 8. Energy Flow
  9. 9. Energy Flow <ul><li>Energy flows in one direction. </li></ul><ul><li>Light energy is transferred into chemical energy through photosynthesis by autotrophic organisms. </li></ul><ul><li>Autotrophs spend some energy to respire and to perform other biological activities. </li></ul><ul><li>The remaining energy is available to heterotrophs at the next trophic level. </li></ul>
  10. 10. Energy Flow
  11. 11. <ul><li>Every time there is an exchange of energy between one trophic level and another, there is a quite a significant loss. </li></ul><ul><li>This means so many units of grass can only support a much smaller number of units of rabbits, who can only support a smaller group of jackals, who can only support a smaller group of predatory birds. </li></ul>
  12. 12. <ul><li>This is why trophic levels are usually portrayed as a pyramid, one that places plants at the bottom and top carnivores at top. </li></ul><ul><li>The top is always much smaller than the bottom. </li></ul><ul><li>Each level implies a loss of energy. </li></ul>
  13. 13. <ul><li>1. The figure below shows part of a food web in Isle Royale National Park. The number of trophic levels shown in this web is _______. </li></ul><ul><li>1 </li></ul><ul><li>2 </li></ul><ul><li>3 </li></ul><ul><li>4 </li></ul><ul><li>5 </li></ul>
  14. 14. <ul><li>Primary producers get their energy directly from the sun. </li></ul><ul><li>The greatest amount of energy loss is through respiration. </li></ul><ul><li>Detritivores receive energy from all other organisms in an ecosystem. </li></ul><ul><li>Secondary carnivores receive a large proportion of the energy produced by photosynthesis. </li></ul><ul><li>Herbivores receive energy from primary producers </li></ul>2. Flow of energy through different organisms in an ecosystem varies widely (below). Which of the following statements regarding energy flow through ecosystems is false?
  15. 15. <ul><li>3. As the number of individuals of the predatory species increases, the prey population </li></ul><ul><li>increases </li></ul><ul><li>Decreases </li></ul><ul><li>Stabilizes </li></ul><ul><li>first increases, and then begins to decrease </li></ul>