BIO 311D 2nd Edition Lecture 39 Outline of Last Lecture I Community Dynamics Ecological Succession II Trophic Interactions and energy flow Outline of Current Lecture I Energy flow and trophic structure How does this affect human k II Nutrient cycling and eutrophication Current Lecture I Energy flow and trophic structure A Index Questions a Photosynthesis is a synthesis reaction not a respiration reaction b Both animals and plants respire and release CO2 1 Plants release CO2 but they use it for photosynthesis c In cell respiration animals and plants release CO2 and in photosynthesis plants release O2 d Carbon fixation building organic compounds e Heat is lost from biological system in the form of heat B Where is photosynthesis occurring C Where is cellular respiration occurring D At each step of the food chain there is a loss of usable energy for biomass production based on 10 efficiency a Which of these helps explain why there is less total biomass in predators at the top of a food chain than in organisms at lower levels Useful energy is lost to cell work and heat at every transfer between levels of the food chain E Where do humans fit in How related to our K a Humans can act both as secondary and primary consumers b What is K for humans on earth c Factors 1 Abundance of water 2 Distribution of food Change our food source 3 Disease density dependent mortality 4 Natural disasters density independent d What is your ecological footprint 1 Available capacity vs ecological footprint ha per person 2 Using ecological footprint to determine the K the earth can hold II Nutrient cycling and eutrophication A Carbon cycle a Producers use CO2 during photosynthesis producing organic compounds b All organisms release CO2 in cellular respiration c Follow a C atom d Greenhouse gases CO2 and methane Global warming trapping heat 1 Reduction in growth of the ozone hole through restriction of fluorinated hydrocarbons hole in the ozone has been getting smaller in the past 10 years B Biological Magnification a Toxins in the environment pesticides heavy metals like mercury plastic residues become more concentrated in successive trophic levels b Affects reproduction success c Banning DDT success story no longer threatened by egg shell thinning eagles peregrine falcon brown pelican California condor d Affecting humans toxic aluminum levels unsafe mercury levels in fish 1 Alters nervous system etc C Nitrogen cycle a Abiotic Biotic b N2 NH3 c Atmospheric nitrogen Ammonia nitrogen fixing bacteria we and plants can t do it d Humans need amino acids that we have to get from our food e How does nitrogen move between biotic and abiotic reservoirs 1 Decomposers important for releasing into abiotic molecule 2 Humans release through uric acid urea into the abiotic reservoir f Cyanobacteria nitrogen fixer prokaryotes carry on photosynthesis trap energy to make food
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