Chapter 9

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 the energy that establishes the proton gradient. (D) are coupled via phosphorylated intermediates to endergonic processes.

What is the oxidizing agent in the following reaction? $${\text {pyruvate}}+\mathrm{NADH}+\mathrm{H}^{+} \rightarrow \text { Lactate }+\mathrm{NAD}^{+}$$ (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.

EVOLUTION CONNECTION ATP synthases are found in the prokaryotic plasma membrane and in mitochondria and chloroplasts. (a) Propose a hypothesis to account for an evolutionary relationship of these eukaryotic organelles and prokaryotes. (b) Explain how the amino acid sequences of the ATP synthases from the different sources could be used to support or refute your hypothesis.

SCIENTIFIC INQUIRY In the 1930 s, some physicians prescribed low doses of a compound called dinitrophenol \((\) DNP ) to help patients lose weight. This unsafe method was abandoned after some patients died. DNP uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to \(\mathrm{H}^{+} .\) Explain how this could cause weight loss and death.