Chapter 6

A biochemist wanted to study how various substances were used in cellular respiration. In one experiment, she allowed a mouse to breathe air containing \(\mathrm{O}_{2}\) "labeled" by a particular isotope. In the mouse, the labeled oxygen first showed up in a. ATP. b. NADH. c. \(\mathrm{CO}_{2}\). d. \(\mathrm{H}_{2} \mathrm{O}\).

In glycolysis, ___ is oxidized and ___ is reduced. a. NAD \(\ldots\) glucose b. glucose ... oxygen C. ATP ... ADP d. glucose ... NAD \(^{+}\)

Most of the \(\mathrm{CO}_{2}\) from cellular respiration is released during a. stage 1: glycolysis. b. stage 2 : pyruvate oxidation. c. stage 2 : the citric acid cycle. d. stage 3: oxidative phosphorylation.

Which of the following is a distinction between cellular respiration and fermentation? a. NADH is oxidized by passing electrons to the electron transport chain in respiration only. b. Only respiration oxidizes glucose. c. Substrate-level phosphorylation is unique to fermentation; cellular respiration uses oxidative phosphorylation. d. Fermentation is the metabolic pathway found in prokaryotes; cellular respiration is unique to eukaryotes.

The poison cyanide binds to an electron carrier within the electron transport chain and blocks the movement of electrons. When this happens, glycolysis and the citric acid cycle soon grind to a halt as well. Why do you think these other two stages of cellular respiration stop? (Explain your answer.) a. They run out of ATP. b. Unused \(\mathrm{O}_{2}\) interferes with cellular respiration. c. They run out of \(\mathrm{NAD}^{+}\) and FAD. d. Electrons are no longer available.

Which of the following is the most immediate source of energy for making most of the ATP in your cells? a. the transfer of P from intermediate substrates to ADP b. the movement of H + across a membrane down its concentration gradient c. the splitting of glucose into two molecules of pyruvate d. electrons moving through the electron transport chain

Oxidative phosphorylation involves the flow of both electrons and \(\mathrm{H}^{+}\). Explain the roles of these movements in the synthesis of ATP.

ATP synthase enzymes are found in the prokaryotic plasma membrane and in the inner membrane of a mitochondrion. What does this suggest about the evolutionary relationship of this eukaryotic organelle to prokaryotes?