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Explore feedback loops in changing environments, interactions among organisms, and evolution of homeostatic mechanisms. Discover how disruptions at molecular/cellular levels and ecosystems impact homeostasis. Case studies on biofilms, nitrogenous waste removal, and circulatory system evolution offer in-depth insights. Learn about mutualism, commensalism, and parasitism in ecosystems. Discover how species adapt to biotic and abiotic factors for survival in dynamic environments.
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Warm Up • What type of feedback loop is occurring here? Why? a) Increase in prey increase in predators decrease in prey
Homeostasis in a Changing Environment Big Idea 2.D: Growth and dynamic homeostasis are influenced by changes in the environment
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.
Organisms Respond to External Environments What is this called???
External Environment Made up of Biotic Things: Living
External Environment And Abiotic Things: Not Living
TPS: With your partner, make a list of 4 other biotic and 4 other abiotic factors that may affect organisms in an environment.
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 w/ limited nutrients.
Organisms Interact with Biotic/Abiotic Factors • Organisms access to nutrients is affected by other factors • i.e. symbiosis, predator-prey, nutrient availability etc
Interactions Among Organisms • Symbiosis: relationship b/t 2 species • Mutualism (+,+) • Commensalism (+,0) • Parasitism (+,-)
Mutualism • Both Species Benefit • Rhinos and oxpeckers
Commensalism • One member is helped, the other neither benefits or is harmed • Cows and Cattle Egrets
Parasitism • + and - relationship • parasite benefits, host loses • parasite usually smaller than host Leech Bite, Thailand Lamprey
Ecosystems’ Stability is based upon interactions w/ biotic or abiotic factors
Evolution of Homeostatic Mechanisms • Some mechanisms are conserved- showing common ancestry • Others have changed, demonstrating divergent evolution (due to changing envs)
Case Study: Nitrogenous Waste Removal • All animals produce N byproducts • Animals in diff. envs. have evolved different mechanisms for excreting these wastes
Ammonia, NH3 • Toxic byproduct of protein degradation • In dilute concentrations is no big deal, so aquatic orgs can excrete it into water
Urea • Mammals convert NH3 into urea travels through blood to kidneys and is excreted w/ water and other substances as urine
Solid Uric Acid • In birds and reptiles (and some desert mammals) N waste is excreted as a solid • Prevents H2O loss and buildup of H2O waste in shell of an egg
Evolution of Circulatory System Shows Common Ancestry and Divergence
Evolution of Circulatory System Shows Common Ancestry and Divergence
Disruptions at the Molecular/Cellular Level Affect Organisms Homeostasis • Exs: viral infection of a cell, allergies, or dehydration in body
Disruptions to Ecosystems Affect Homeostasis • Exs: food chain disruptions, natural disasters, salination (adding salt)