IB Bio HL Paper 3 – Ecology and Conservation
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gross production
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the amount of organic matter (biomass) produced by plants
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net production
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the amount of organic matter produced by plants minus what is needed for plant respiration
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biomass
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the total dry organic matter of living organisms or ecosystems
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Net Production Formula
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Gross Production - Respiration
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Why is it difficult to classify organisms in higher trophic levels?
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-Organism may fit into more than one trophic level -Omnivores consume organisms from all levels of the food chain -Seasonal changes (food supply) -Organisms alter their diet over their lifetime
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Primary Succession
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-entirely new land w/o established soil -pioneer communities establish a new layer of soil
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Nitrification
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the biological oxidation of ammonia to produce nitrate ions
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Denitrification
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the biological process of nitrate reduction to produce molecular nitrogen (N2)
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Nitrogen Fixation
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Rhizobium is found in the root nodules of certain leguminous plants and fixes nitrogen gas into ammonia for its host. Azotobacter is found living freezing in the soil and fixes nitrogen but without the need of a host
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Nitrification - cycle
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Nitrosomonas is able to convert ammonium (NH4+) into nitrites (No2-) Nitrobacter is able to convert the nitrites (NO2-) into nitrates (NO3-) which can be absorbed by plant roots via active transport
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Denitrification
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Pseudomonas denitrificans is able to convert nitrites (NO2-) and nitrates (NO3-) into nitrogen gas (N2), which can return to the atmosphere
