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Big Idea 2.D: Growth and dynamic homeostasis are influenced by changes in the environment Homeostasis in a Changing Environment
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Essential Knowledge 2D1: All biological systems from cells to organisms to populations, communities, and ecosystems are affected by complex biotic and abiotic interactions involving exchange of matter and free energy. 2D2: Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments. 2D3: Biological systems are affected by disruptions to their dynamic homeostasis.
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Organisms Respond to External Environments What was this called???
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External Environment Made up of Biotic Things: Living
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And Abiotic Things: Not Living External Environment
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TPS: With your partner, make a list of 4 other biotic and 4 other abiotic factors that may affect organisms in an environment.
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Case Study: Biofilms Bacterial cells attach to each other to form biofilms (a protective protein matrix cover) Communal group for protection and shared nutrients Grow with limited nutrients.
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Cells Interact with Biotic/Abiotic Factors
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Organisms Interact with Biotic/Abiotic Factors Organisms access to nutrients is affected by other factors i.e. symbiosis, predator-prey, nutrient availability etc
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Interactions Among Organisms Symbiosis: relationship b/t 2 species Mutualism (+,+) Commensalism (+,0) Parasitism (+,-)
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Mutualism Both Species Benefit Rhinos and oxpeckers
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Commensalism One member is helped, the other neither benefits or is harmed Cows and Cattle Egrets
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Parasitism + and - relationship parasite benefits, host loses parasite usually smaller than host Leech Bite, Thailand Lamprey
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Ecosystems’ Stability is based upon interactions w/ biotic or abiotic factors
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Evolution of Homeostatic Mechanisms Some mechanisms are conserved- showing common ancestry Others have changed, demonstrating divergent evolution (due to changing envs)
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Case Study: Nitrogenous Waste Removal All animals produce N byproducts Animals in diff. envs. have evolved different mechanisms for excreting these wastes
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Ammonia, NH 3 Toxic byproduct of protein degradation In dilute concentrations is no big deal, so aquatic orgs can excrete it into water
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Urea Mammals convert NH 3 into urea travels through blood to kidneys and is excreted w/ water and other substances as urine
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Solid Uric Acid In birds and reptiles (and some desert mammals) N waste is excreted as a solid Prevents H 2 O loss and buildup of H 2 O waste in shell of an egg
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Evolution of Circulatory System Shows Common Ancestry and Divergence
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Disruptions at the Molecular/Cellular Level Affect Organisms Homeostasis Exs: viral infection of a cell, allergies, or dehydration in Willis’s body ;)
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Disruptions to Ecosystems Affect Homeostasis Exs: food chain disruptions, natural disasters, salination (adding salt)
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