2.3 ecology notes


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2.3 ecology notes

  1. 1. Ecosystems and the Biosphere
  2. 2. Energy Transfer <ul><li>All organisms need energy to carry out essential functions – growth, movement, maintenance, repair, and reproduction </li></ul><ul><li>In ecosystems, energy flows from sun to autotrophs to organisms that eat autotrophs to organisms that feed on other organisms. </li></ul><ul><li>Amount of energy ecosystem receives and the amount. transferred from organism to organism have an effect on the ecosystem’s structure. </li></ul>
  3. 3. Energy Flow <ul><li>Whenever one organism eats another, molecules are metabolized and energy is transferred. </li></ul><ul><li>Energy flows through an ecosystem from producer to consumer </li></ul>
  4. 4. Trophic level <ul><li>Trophic level indicates the organism’s level of nourishment, or position in the sequence of energy transfer illustration </li></ul><ul><ul><li>First level – all producers </li></ul></ul><ul><ul><li>Second level – herbivores </li></ul></ul><ul><ul><li>Third level – predators of herbivores </li></ul></ul>
  5. 5. Food Chain <ul><li>single pathway of feeding relationship that results in energy transfer to mouse to snake to hawk </li></ul><ul><li>Feeding relationships in ecosystems are usually too complex to be represented by a single food chain. </li></ul><ul><li>Many consumers eat more than one type of food and many organisms may feed on the same organisms. </li></ul>
  6. 6. Food Web <ul><li>Models of complex feeding networks within ecosystems; series of food chains interwoven </li></ul>
  7. 7. Energy Pyramid <ul><li>distribution of energy and matter in an ecosystem </li></ul><ul><li>Shows the distribution of energy in a food chain </li></ul><ul><li>Energy flows upwards from producers to consumers </li></ul><ul><li>Energy is lost as head between each tier of the pyramid; average of 10% of energy is passed from one level to the next level </li></ul>
  8. 8. Other Pyramids <ul><li>Biomass pyramid shows the total mass or organisms at each tropic level </li></ul><ul><ul><li>Less biomass at higher tropic levels than lower levels </li></ul></ul><ul><li>Pyramid of numbers shows the actual number of organisms present in each trophic level </li></ul>
  9. 9. Water Cycle <ul><li>Crucial to life - ells are 70-90% water </li></ul><ul><li>90% of water evaporates from terrestrial ecosystems passes through plants in a process called transpiration – plants take in water through roots and release water and take in CO 2 through the stomata in their leaves </li></ul><ul><li>In pic to right note: evaporation, condensation precipitation, transpiration </li></ul>
  10. 10. Carbon Cycle <ul><li>Photosynthesis and cellular respiration form the basis of carbon cycle </li></ul><ul><li>In photosynthesis, plants use carbon dioxide , water, and solar energy to make carbohydrates and produce oxygen </li></ul><ul><li>Both autrotrophs and heterotrophs use oxygen to break down carbohydrates during cellular respiration </li></ul>
  11. 11. Nitrogen Cycle The most important thing about the nitrogen cycle is that bacteria are involved <ul><li>All organisms need nitrogen to make proteins and nucleic acids. </li></ul><ul><li>Nitrogen gas makes up about 78% of the atmosphere. </li></ul><ul><li>Bacteria break down the corpses and wastes of organisms and release the nitrogen they contain as ammonia – ammonification. </li></ul><ul><li>Bacteria in the soil takes the ammonia and oxides it into nitrites – nitrification. </li></ul><ul><li>Nitrogen is returned to the atmosphere through denitrification. </li></ul><ul><li>Plants can absorb nitrates from the soil, but animals cannot. Animals get nitrogen by eating plants and other organisms and then digesting the proteins and nucleic acids. </li></ul>