Chapter 12 Energy Flow Through Ecosystems I.Teaching Objective: Ecosystem as energy-transforming machine Obeys thermodynamic principles Law 1:Conservation of energy>none lost:have to'balance books' Law 2:Inefficient transfer of energyheat loss in biochemical transformations Energy flows through food chains Food chains represent energy relationships Trophic level-one link in a chain Pyramids of Energy-can't be inverted Biomass-may be inverted IL.Focal Points and Difficulties in the Chapter(教学重点和难点) Laws of Thermodynamies Lindeman's law of trophic efficieney and pyramids 2.Difficulties Efficiency of energy transfer 3.Main contents Link the laws of thermodynamics and energy flow through ecosystems. Laws of Thermodynamics Primary and secondary production Energy flow and ecological pyramids Efficiency of energy transfer Biomagnification I.Methodology Powerpoint presentation will be the main method.Blackboard will be an 2