Question 1

Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid (see Figure 7.1)?

Accepted Answer

A)  succinate 
B)  malate 
C)  citrate 
D)  α-ketoglutarate 
E)  isocitrate

Question 2

Which catabolic processes may have been used by cells on ancient Earth before free oxygen became available?

Accepted Answer

A)  glycolysis and fermentation only 
B)  glycolysis and the citric acid cycle only 
C)  glycolysis, pyruvate oxidation, and the citric acid cycle 
D)  oxidative phosphorylation only 
E)  glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen

Question 3

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the

Accepted Answer

A)  oxidation of glucose and other organic compounds. 
B)  flow of electrons down the electron transport chain. 
C)  affinity of oxygen for electrons. 
D)  H+ movement down its concentration gradient. 
E)  transfer of phosphate to ADP.

Question 4

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

Accepted Answer

A)  The pH of the matrix increases. 
B)  ATP synthase pumps protons by active transport. 
C)  The electrons gain free energy. 
D)  The cytochromes phosphorylate ADP to form ATP. 
E)  NAD+ is oxidized.

Question 5

Inside an active mitochondrion, most electrons follow which pathway?

Accepted Answer

A)  glycolysis → NADH → oxidative phosphorylation → ATP → oxygen 
B)  citric acid cycle → FADH2 → electron transport chain → ATP 
C)  electron transport chain → citric acid cycle → ATP → oxygen 
D)  pyruvate → citric acid cycle → ATP → NADH → oxygen 
E)  citric acid cycle → NADH → electron transport chain → oxygen

Question 6

What is the purpose of beta oxidation in respiration?

Accepted Answer

A)  oxidation of glucose 
B)  oxidation of pyruvate 
C)  feedback regulation 
D)  control of ATP accumulation 
E)  breakdown of fatty acids

Question 7

In glycolysis, for each molecule of glucose oxidized to pyruvate

Accepted Answer

A)  two molecules of ATP are used and two molecules of ATP are produced. 
B)  two molecules of ATP are used and four molecules of ATP are produced. 
C)  four molecules of ATP are used and two molecules of ATP are produced. 
D)  two molecules of ATP are used and six molecules of ATP are produced. 
E)  six molecules of ATP are used and six molecules of ATP are produced.

Question 8

Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?

Accepted Answer

A)  electron transport 
B)  glycolysis 
C)  the citric acid cycle 
D)  oxidative phosphorylation 
E)  chemiosmosis

Question 9

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?

Accepted Answer

A)  NAD+ 
B)  NADH 
C)  ATP 
D)  ADP + ℗i 
E)  FADH2

Question 10

Where is ATP synthase located in the mitochondrion?

Accepted Answer

A)  cytosol 
B)  electron transport chain 
C)  outer membrane 
D)  inner membrane 
E)  mitochondrial matrix

Question 11

In cellular respiration, the energy for most ATP synthesis is supplied by

Accepted Answer

A)  high-energy phosphate bonds in organic molecules. 
B)  a proton gradient across a membrane. 
C)  converting oxygen to ATP. 
D)  transferring electrons from organic molecules to pyruvate. 
E)  generating carbon dioxide and oxygen in the electron transport chain.

Question 12

A young dog has never had much energy. He is brought to a veterinarian for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition?

Accepted Answer

A)  His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. 
B)  His cells cannot move NADH from glycolysis into the mitochondria. 
C)  His cells contain something that inhibits oxygen use in his mitochondria. 
D)  His cells lack the enzyme in glycolysis that forms pyruvate. 
E)  His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.

Question 13

Starting with one molecule of glucose, the energy-containing products of glycolysis are

Accepted Answer

A)  2 NAD+, 2 pyruvate, and 2 ATP. 
B)  2 NADH, 2 pyruvate, and 2 ATP. 
C)  2 FADH2, 2 pyruvate, and 4 ATP. 
D)  6 CO2, 2 pyruvate, and 2 ATP. 
E)  6 CO2, 2 pyruvate, and 30 ATP.

Question 14

What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions?

Accepted Answer

A)  glucose 
B)  ethanol 
C)  pyruvate 
D)  lactic acid 
E)  either ethanol or lactic acid

Question 15

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?

Accepted Answer

A)  It allows for an increased rate of glycolysis. 
B)  It allows for an increased rate of the citric acid cycle. 
C)  It increases the surface for oxidative phosphorylation. 
D)  It increases the surface for substrate-level phosphorylation. 
E)  It allows the liver cell to have fewer mitochondria.

Question 16

During intense exercise, as skeletal muscle cells switch to fermentation, the human body will increase its catabolism of

Accepted Answer

A)  fats only. 
B)  carbohydrates only. 
C)  proteins only. 
D)  fats, carbohydrates, and proteins. 
E)  fats and proteins only.

Question 17

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

Accepted Answer

A)  oxygen. 
B)  water. 
C)  NAD+. 
D)  pyruvate. 
E)  ADP.

Question 18

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells?

Accepted Answer

A)  The mutant yeast will be unable to grow anaerobically. 
B)  The mutant yeast will grow anaerobically only when given glucose. 
C)  The mutant yeast will be unable to metabolize glucose. 
D)  The mutant yeast will die because they cannot regenerate NAD+ from NAD. 
E)  The mutant yeast will metabolize only fatty acids.

Question 19

In alcohol fermentation, NAD+ is regenerated from NADH by

Accepted Answer

A)  reduction of acetaldehyde to ethanol (ethyl alcohol). 
B)  oxidation of pyruvate to acetyl CoA. 
C)  reduction of pyruvate to form lactate. 
D)  oxidation of ethanol to acetyl CoA. 
E)  reduction of ethanol to pyruvate.

Question 20

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

Accepted Answer

A)  glycolysis and the oxidation of pyruvate to acetyl CoA 
B)  oxidation of pyruvate to acetyl CoA and the citric acid cycle 
C)  the citric acid cycle and oxidative phosphorylation 
D)  oxidative phosphorylation and fermentation 
E)  fermentation and glycolysis

Exam 7: Cellular Respiration and Fermentation

Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid (see Figure 7.1) ?