Bio171-F08-Lec%206

Bio171-F08-Lec%206 - Lecture 6 Energy Flow& Cycling of...

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Unformatted text preview: Lecture 6: Energy Flow & Cycling of Matter Biology 171 Monday September 15, 2008 Today’s Topics: Announcements This Week in Discussion: Global Warming Text Reading: Lecture 6: 2 nd ed: Chapter 54 (1243-1258) 3 rd ed: Chapter 54 (1222-1237) Lecture 7: 2 nd ed: Chapter 54 (1259-1261) 3 rd ed: Chapter 54 (1238-1241) Exam Format Overview Ecosystem Ecology Energy & Nutrient Dynamics Primary Production & Limiting Factors Biogeochemical Cycles: Water & Nitrogen Eutrophication & Bioamplifcation Personal Emissions Calculator This week’s discussion contains a detailed (and somewhat surprising) breakdown of a typical Briton’s “carbon footprint” (fossil fuel CO 2 emissions). Prior to your section, calculate your own footprint using one of the sites below, then scroll down the page to view options for cutting your emissions. Bring your estimate to class and be prepared to engage……… http://www.fightglobalwarming.com/carboncalculator.cfm http://www.epa.gov/climatechange/emissions/ind_calculaor.html An ecosystem consists of all the organisms in a particular region, along with nonliving, or abiotic, components. Ecosystem ecologists study how nutrients and energy move between organisms and the surrounding atmosphere, soil, or water ( Figure 50.1d ). Why We Care • Ecosystem ecology seeks to explain the transfer of energy and cycling of matter within ecosystems • Without energy transfer, there would be no heterotrophic organisms and therefore we could not exist • Without the cycling of matter (nutrients like nitrogen), the soil would lose fertility, there would be no plants and, once again, we could not exist • Ecosystem ecologists can address environmental issues that are caused or exacerbated by changes in nutrient cycles and energy flow Key concept: Energy flows but matter cycles 1 st Law of Thermodynamics • “Energy is neither created nor destroyed” • The amount of energy in the universe today is the same amount that was in the universe when it was created • Energy can be transferred from one body to another • Energy can be transformed from one form to another • Ecosystems are energy transformers Energy Transformers Light Energy Chemical Energy Work & Heat Light Energy + CO 2 + H 2 Sugar + O 2 CO 2 + H 2 0 + Work + Heat Energy Transformation in Ecosystems is Unidirectional Energy flow links four components in every ecosystem: primary producers, consumers, decomposers, and the abiotic environment ( Figure 54.1 ). A food web describes the pathways of energy and materials transfer through different trophic levels (producer, primary & secondary, etc....
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Bio171-F08-Lec%206 - Lecture 6 Energy Flow& Cycling of...

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