BIOLOGY 220 LECTURE #17 - Notes - 10-30-07

BIOLOGY 220 LECTURE #17 - Notes - 10-30-07 - Biology 220...

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Biology 220 Lecture #17 – Nutrient Cycling, Primary Production, and Trophic Interactions - 11/4/07 ENERGY UNIT – (2) Primary Production and Trophic interactions are very important in this lecture Abiotic factors in an environment – not living – mostly chemistry and certain compounds, etc. o Soil is half living (biotic), half abiotic minerals Anything that is living falls into the category of living organisms – biotic o Fecal matter is including o Anything that was living is biotic How do nutrients get from abiotic to biotic? o Abiotic strata (layer or area) – How do nutrients go from abiotic strata to biotic realm (into organisms)? Carbon fixation, nitrogen fixation, all fixation processes Direct uptake – plants suck stuff up from the soil using their roots Consumption and breakdown by respiration o We move nutrients from abiotic strata up into the body OBTAINING ENERGY – (3) Autotrophy o Plants, bacteria, certain algae o Realm of photosynthesis Heterotrophy o Eating something else to get carbon and energy they need OBTAINING ENERGY – (4) Autotrophs can also be called primary producers o Can make own organic compounds using CO2 as carbon source 2 CATEGORIES Chemoautotrophs – Use chemical energy o Get electrons from oxidizing or manipulating chemical substrates o Nitrifying bacteria o Oxidizing other things Photoautotrophs o Capturing sunlight to perform photosynthesis Both of these categories are fixing carbon to make their own food They just use other sources of energy to make their own food
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OBTAINING ENERGY – (5) Chemoautotrophs do not need light to produce their own food – use chemical energy! OBTAINING ENERGY – (6) Heterotrophs are called consumers o Get carbon and energy sources from organic compounds o We eat sugars and other things to power body Photosynthetic bacteria – gather their carbon separately and use sunlight to break things down PRIMARY PRODUCTION – (7) How much living tissue, biotic mass is present in an ecosystem Ecosystem’s productivity How much biomass is produced by a particular ecosystem Literally, the mass of living tissue per area How much of the nutrients in that system (nitrogen, carbon, etc.) are being turned into living tissue What kind of biological tissue is being produced by autotrophs We measure primary production in all ecosystems: o This tells us how well the ecosystem is doing o The more biomass the more productive the ecosystem is o Problem is that you have to take into account that all organisms respire Not all carbon that goes into an organism’s body is turned into body mass A lot of it is lost to chemical reactions Gross primary production – how much carbon is taken from the environment and put into tissue o GPP – Always the larger value relative to net primary production (NPP) If you are just talking about what goes into a system, that’s GPP Net primary production – Takes into account the amount that is lost to respiration.
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BIOLOGY 220 LECTURE #17 - Notes - 10-30-07 - Biology 220...

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