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2.3 ecology notes

2.3 ecology notes






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    2.3 ecology notes 2.3 ecology notes Presentation Transcript

    • Ecosystems and the Biosphere
    • Energy Transfer
      • All organisms need energy to carry out essential functions – growth, movement, maintenance, repair, and reproduction
      • In ecosystems, energy flows from sun to autotrophs to organisms that eat autotrophs to organisms that feed on other organisms.
      • Amount of energy ecosystem receives and the amount. transferred from organism to organism have an effect on the ecosystem’s structure.
    • Energy Flow
      • Whenever one organism eats another, molecules are metabolized and energy is transferred.
      • Energy flows through an ecosystem from producer to consumer
    • Trophic level
      • Trophic level indicates the organism’s level of nourishment, or position in the sequence of energy transfer illustration
        • First level – all producers
        • Second level – herbivores
        • Third level – predators of herbivores
    • Food Chain
      • single pathway of feeding relationship that results in energy transfer to mouse to snake to hawk
      • Feeding relationships in ecosystems are usually too complex to be represented by a single food chain.
      • Many consumers eat more than one type of food and many organisms may feed on the same organisms.
    • Food Web
      • Models of complex feeding networks within ecosystems; series of food chains interwoven
    • Energy Pyramid
      • distribution of energy and matter in an ecosystem
      • Shows the distribution of energy in a food chain
      • Energy flows upwards from producers to consumers
      • 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
    • Other Pyramids
      • Biomass pyramid shows the total mass or organisms at each tropic level
        • Less biomass at higher tropic levels than lower levels
      • Pyramid of numbers shows the actual number of organisms present in each trophic level
    • Water Cycle
      • Crucial to life - ells are 70-90% water
      • 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
      • In pic to right note: evaporation, condensation precipitation, transpiration
    • Carbon Cycle
      • Photosynthesis and cellular respiration form the basis of carbon cycle
      • In photosynthesis, plants use carbon dioxide , water, and solar energy to make carbohydrates and produce oxygen
      • Both autrotrophs and heterotrophs use oxygen to break down carbohydrates during cellular respiration
    • Nitrogen Cycle The most important thing about the nitrogen cycle is that bacteria are involved
      • All organisms need nitrogen to make proteins and nucleic acids.
      • Nitrogen gas makes up about 78% of the atmosphere.
      • Bacteria break down the corpses and wastes of organisms and release the nitrogen they contain as ammonia – ammonification.
      • Bacteria in the soil takes the ammonia and oxides it into nitrites – nitrification.
      • Nitrogen is returned to the atmosphere through denitrification.
      • 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.