The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the a. oxidation of glucose and other organic compounds. b. flow of electrons down the electron transport chain. c. H+ concentration gradient across the membrane holding ATP synthase. d. transfer of phosphate to ADP.

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? a. the citric acid cycle b. the electron transport chain c. glycolysis d. reduction of pyruvate to lactate

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is a. oxygen. b. water. c. NAD+. d. pyruvate.

In mitochondria, exergonic redox reactions a. are the source of energy driving prokaryotic ATP synthesis. b. provide the energy that establishes the proton gradient. c. reduce carbon atoms to carbon dioxide. d. are coupled via phosphorylated intermediates to endergonic processes

What is the oxidizing agent in the following reaction? Pyruvate+NADH+H+→Lactate+NAD+ a. oxygen b. NADH c. lactate d. pyruvate

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? a. The pH of the matrix increases. b. ATP synthase pumps protons by active transport. c. The electrons gain free energy. d. NAD+ is oxidized.

Most CO2 from catabolism is released during a. glycolysis. b. the citric acid cycle. c. lactate fermentation. d. electron transport.

MAKE CONNECTIONS Step 3 in Figure 9.9 is a major point of regulation of glycolysis. The enzyme phosphofructokinase is allosterically regulated by ATP and related molecules (see Concept 8.5). Considering the overall result of glycolysis, would you expect ATP to inhibit or stimulate activity of this enzyme? Explain. (Hint: Make sure you consider the role of ATP as an allosteric regulator, not as a substrate of the enzyme.)

MAKE CONNECTIONS The proton pump shown in Figures 7.17 and 7.18 is a type of ATP synthase (see Figure 9.14). Compare the processes shown in the two figures, and say whether they are involved in active or passive transport (see Concepts 7.3 and 7.4).

VISUAL SKILLS This computer model shows the four parts of ATP synthase, each part consisting of a number of polypeptide subunits (the structure in gray is still an area of active research). Using Figure 9.14 as a guide, label the rotor, stator, internal rod, and catalytic knob of this molecular motor.