Question
What is the primary purpose of fermentation?
(A) to generate ATP
(B) to generate pyruvate
(C) to generate NAD+
(D) to generate carbon dioxide
▶️Answer/Explanation
Ans:
(C) Fermentation oxidizes NADH into NAD+
so that NAD+
can be
used in glycolysis. Choice (A) is incorrect because fermentation does
not produce ATP. Pyruvate is a reactant used in fermentation, not a
product of fermentation, so choice (B) is incorrect. While carbon
dioxide is a product of alcohol fermentation, carbon dioxide is not
always produced by fermentation (for example, lactic acid fermentation
does not produce carbon dioxide). So choice (D) is incorrect.
Question
Which of the following processes does NOT release carbon dioxide?
(A) glycolysis
(B) oxidation of pyruvate
(C) Krebs cycle
(D) alcohol fermentation
▶️Answer/Explanation
Ans:
(A) Glycolysis does not produce carbon dioxide. Choices (B), (C), and
(D) all produce carbon dioxide, so all three of those choices are
incorrect.
Question
Which of the following statements about glycolysis is NOT correct?
(A) Glycolysis occurs in the cytosol.
(B) Glycolysis can be carried out by all living organisms.
(C) The enzymes of glycolysis are highly conserved.
(D) Glycolysis produces a proton gradient.
▶️Answer/Explanation
Ans:
(D) Glycolysis does not produce a proton gradient; the movement of
electrons down the electron transport chain produces a proton gradient.
Choices (A), (B), and (C) are all true statements about glycolysis.
Notice that this question was asking for the statement about glycolysis
that is NOT correct, which is choice (D).
Question
A mutation in mitochondrial DNA causes the creation of a pore in the mitochondrial membrane through which protons can freely pass.
Which of the following processes would most likely be disrupted by this mutation?
(A) glycolysis
(B) Krebs cycle
(C) chemiosmosis
(D) fermentation
▶️Answer/Explanation
Ans:
(C) Chemiosmosis uses a proton gradient to drive the production of
ATP. If protons were able to pass freely through the inner
mitochondrial membrane, a proton gradient could not be formed and
chemiosmosis could not occur. Glycolysis (choice (A)), the Krebs
cycle (choice (B)), and fermentation (choice (D)) do not require a
proton gradient, so those processes would not be directly affected.
Thus, choices (A), (B), and (D) are not correct.
Question
During oxidative phosphorylation, ____________ is ____________, and oxygen is ____________.
(A) NADH; oxidized; produced
(B) NADH; oxidized; reduced
(C) NAD+ ; reduced; oxidized
(D) NAD+ ; reduced; produced
▶️Answer/Explanation
Ans:
(B) During oxidative phosphorylation, NADH is oxidized to NAD+
and
oxygen is reduced to water. Choice (A) is incorrect because oxygen is
not produced in oxidative phosphorylation. Choice (C) is incorrect
because, during oxidative phosphorylation, NAD+ is not reduced and
oxygen is not oxidized (it is reduced). Choice (D) is incorrect because NAD+ is not reduced and oxygen is not produced during oxidative
phosphorylation.