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Section III – Bioenergetics
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Which one of the following statements about the free energy change (ΔG) in a biochemical reaction is CORRECT?
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A. If ΔG is negative, the reaction proceeds spontaneously with a loss of free energy.
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B. In an exergonic reaction, ΔG is positive.
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C. The standard free energy change when reactants are present in concentrations of 1.0 mol/L and the pH is 7.0 is represented as ΔG0.
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D. In an endergonic reaction there is a loss of free energy.
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E. If a reaction is essentially irreversible, it has a high positive ΔG.
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A reaction with a negative ΔG is exergonic, it proceeds spontaneously and free energy is released.
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If the ΔG of a reaction is zero:
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A. The reaction goes virtually to completion and is essentially irreversible.
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B. The reaction is endergonic.
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C. The reaction is exergonic.
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D. The reaction proceeds only if free energy can be gained.
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E. The system is at equilibrium and no net change occurs.
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In an exergonic reaction ΔG is negative and in an endergonic reaction it is positive. When ΔG is zero, the reaction is at equilibrium.
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ΔG0’ is defined as the standard free energy charge when:
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A. The reactants are present in concentrations of 1.0 mol/L.
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B. The reactants are present in concentrations of 1.0 mol/L at pH 7.0.
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C. The reactants are present in concentrations of 1.0 mmol/L at pH 7.0.
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D. The reactants are present in concentrations of 1.0 μmol/L.
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E. The reactants are present in concentrations of 1.0 mol/L at pH 7.4.
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When the reactants are present in concentrations of 1.0 mol/L, ΔG0 is the standard free-energy change. For biochemical reaction, the pH (7.0) is also defined and this is ΔG0′.
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Which of the following statements about ATP is CORRECT?
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A. It contains three high-energy phosphate bonds.
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B. It is needed in the body to drive exergonic reactions.
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