Chapter 3 Lecture Outline 1

Chapter 3 Lecture - Homeostasis Defined-organisms ability to maintain constant internal conditions in the face of varying external environment

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Homeostasis Defined-organism’s ability to maintain constant internal conditions in the face of varying external environment Maintaining a constant body temperature, salts, carbon dioxide Counteract external changes in order to maintain internal conditions-called negative feedback(ex. Thermostat in a house) Adaptation Structure and function of organisms are products of evolutionary change Changes over time are called adaptations. Results of natural selection: o Organisms best suited for environment survive and produce offspring. Adaptations are a result of natural selection – organisms best suited survive and produce offspring Homeostasis in Plants Water Balance Plants obtains water through the cell membranes of their roots Osmosis-diffusion of fluids across a cell membrane When a plant absorbs water from the roots-example. Solutes-water with substances dissolved in it. Water moves from low solute concentration to high solute concentration Solutes move through the water in the opposite direction. Obtain water through roots from the soil o High solutes in roots, water moves into roots o Occurs until concentrations are equal. o Water moves from roots to leaves due to transpiration. o Plant is replacing water loss in the leaves. o
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This note was uploaded on 12/15/2010 for the course BIO 210 taught by Professor Bilbrey during the Fall '10 term at UCM.

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Chapter 3 Lecture - Homeostasis Defined-organisms ability to maintain constant internal conditions in the face of varying external environment

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