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Unformatted text preview: mount of energy is unchanged when the block slides down the ramp • The 2nd part of the 1st law states that energy can neither be created nor destroyed so the total amount of energy in the universe remains the same. • What is the answer to the previous question? • What became of the energy that was in the block at the top of the ramp? Answer the following questions as a group: as • Describe the energy transformations that occur as you drive your car. • Do you have as much gasoline when you get to school as you had when you left home? • Why or why not? • What happened to the energy that was in the combusted gasoline? The Second Law of Thermodynamics Thermodynamics • According to the second law of thermodynamics • Spontaneous changes that do not require outside energy increase the entropy, or disorder, of the universe Heat co2 + H2 O (b) Figure 8.3 Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism. Free-Energy Change, ∆ G • A living system’s free energy • Is energy that can do work under cellular conditions • The change in free energy, ∆G during a biological process • Is related to the change in entropy Free Energy and Stability Free • Organisms live at the expense of free energy • During a spontaneous change • Free energy decreases and the stability of a system increases Exergonic and Endergonic Reactions in Metabolism Metabolism • An exergonic reaction • Proceeds with a net release of free energy and is spontaneous Free energy Reactants Amount of energy released (∆G <0) Energy Products Progress of the reaction Figure 8.6 (a) Exergonic reaction: energy released • An endergonic reaction • Is one that absorbs free energy from its surroundings and is nonspontaneous Free energy Products Energy Reactants Progress of the reaction Figure 8.6 (b) Endergonic reaction: energy required Amount of energy released (∆G>0) Equilibrium and Metabolism Equilibrium • Re...
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This note was uploaded on 11/09/2011 for the course BIO 181 taught by Professor Staff during the Summer '10 term at Chandler-Gilbert Community College.

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