Energy & Ecosystems

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  • Energy & Ecosystems
    • Transfer of energy in an ecosystem
      • A food chain shows how energy is transferred from one living organism to another
      • The level at which an organism feeds is their 'trophic' level
    • Food Webs
      • Living organisms are usually part of more than one food chain
        • They feed at different trophic levels in different chains
      • Forming the food chains into food webs to understand energy flow in an ecosystem
    • Efficiency of Energy Transfer
      • Energy flow is very inefficient
      • Energy is lost from the food chain at each trophic level and is therefore unavailable to the next organism in the chain
        • Energy is lost as heat due to respiration
      • Some energy remains stored in dead organisms and waste material
        • This energy is then only available to decomposers
      • Only approximately 10% of the energy ends up as herbivore biomass
      • Carnivores are more efficient at energy transfer because they are more efficient at digesting their high protein diets
      • Energy loss can also be because of movement / muscle contraction
      • There tends to be no more than 5 trophic levels within a chain because there would not be enough energy to sustain a further trophic level
    • Photo-synthetic Efficiency
      • The measure of how well a plant is able to capture light energy and convert it into chemical energy
      • The energy flow from one organism to another originates from sunlight
      • GPP = Gross Primary Productivity
        • The total energy transferred/ fixed by a plant
      • A substantial amount of GPP is respired by the plant.
        • What's left over is known as NPP - Net Primary Production
          • It represents the potential food available to primary consumers - in plants this may be as low as 1%

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