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???

Made up of Biotic Things: Living External Environment Made up of Biotic Things: Living

And Abiotic Things: Not 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 http://bacteriality.com/2008/05/26/biofilm/ 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.

Cells Interact with Biotic/Abiotic Factors

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

One member is helped, the other neither benefits or is harmed 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

Toxic byproduct of protein degradation 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

Exs: viral infection of a cell, allergies, or dehydration in body 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)