ch 9 notes

ch 9 notes - Secondary: heterotrophs consume other...

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BIOLOGICAL PRODUCTIVITY AND ENERGY FLOW Biological production – production of biomass (organic matter) Review: energy -ability to make something move kilocalorie (kcal) kilojoule (kJ) – preferred unit Thermodynamics: 1 st Law – energy neither created nor destroyed, just changes form 2 nd Law- when energy changes form there is a loss of usable energy Energy quality - usability Entropy - disorder Energy flow in ecosystems: Photosynthesis: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 requires sunlight, pigments,enzymes Cellular respiration: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O Biological production is limited by the laws of thermodynamics Currencies of production: biomass (g) energy content (kJ/g) carbon content Some typical values: Organic material Energy content (kJ/g) Fat 38 Muscle 25 Vegetation 21 Roots 19 Wood 17
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BIOLOGICAL PRODUCTIVITY AND ENERGY FLOW Biological Production - organisms take in and use energy to make molecules 2 types: Primary: autotrophs – use light energy to make biomass
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Unformatted text preview: Secondary: heterotrophs consume other organisms to make biomass Primary versus secondary production: Gross production total biomass produced Net production biomass remaining after respiration respiration use of biomass to release energy to maintain cells Net Production = Gross Production - Respiration Example: human body - no weight gain means no net production most of energy released as heat during respiration Energy efficiencies: efficiency ratio of output to input amount of useful work obtained from a given amount of energy % efficiency = energy out x 100 energy in trophic level efficiency (food chain efficiency) - between trophic levels production level n x 100 production level n-1 growth efficiency how efficient organisms are at converting food to biomass within a trophic level production x 100 consumption no units, always < 100%...
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ch 9 notes - Secondary: heterotrophs consume other...

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