General Biology, Quiz 4: Metabolism Questions With Complete Solutions

Which of the following reactions could be driven by coupling to the hydrolysis of ATP? The change in free energy is given in units of kilojoules per mole ATP + H2O → ADP + Pi (-30.5) A. Maltose + H2O → 2 Glucose (-15.5) B. Pyruvate + Pi → Phosphoenolpyruvate (+31.7) C. Glycerol + Pi → Glycerol phosphate (+9.2) correct answer: C The example of water freezing into ice shows A. a decrease in entropy of the system. B. an increase in entropy of the system. C. no change in the entropy of the system. D. a decrease in the entropy of the surroundings. correct answer: A Which of the following is true about exergonic reactions? A. The products of exergonic reactions have more free energy than the reactants. B. Energy is released from the reactants. C. There is a positive ΔG. correct answer: B Suppose that three critical amino acids in the active site of a specific enzyme are arginine, lysine, and histidine. Which of the following characteristics would you predict the substrate to possess in order to bind to the active site of this enzyme? Note: Use amino acid classification table to determine chemical reactivity of amino acids at physiological pH A.relatively hydrophobic B.hydrophilic, with a positive charge C.hydrophilic, with a negative charge D.hydrophilic, without a charge correct answer: C Which of the following statements regarding enzymes is true? A. Enzymes increase the rate of a reaction by making the reaction more exergonic. B. Enzymes increase the rate of a reaction by lowering the activation energy barrier. C. Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. D. Enzymes change the equilibrium point of the reactions they catalyze. correct answer: B Following the citric acid cycle but before the electron transport chain and oxidative phosphorylation, most of the energy from the original glucose molecule is found in: A. acetyl-CoA B. CO2 C. pyruvate D. NADH E. ATP correct answer: D The phosphofructokinase (PFK) enzyme is one of the key players in the glycolytic pathway in which glucose eventually breaks down into pyruvate, some ATP is generated, and some NAD+ is reduced. PFK catalyzes the committed step in the pathway and is under extensive regulation. Which of the following compounds would you expect to activate PFK? A. ATP B. NADH C. Pyruvate D. ADP E. All of the above correct answer: D In the final stage of the oxidation of food molecules, a gradient of protons is formed across the inner mitochondrial membrane, which is normally impermeable to protons. If cells were exposed to an agent that causes the membrane