Chapter 9 Homework

In muscle cells, fermentation produces _____. A) Carbon dioxide, ethanol, and NAD+ B) Carbon dioxide, ethanol, NADH, and ATP C) Lactate and NAD+ D) Lactate, NADH, and ATP E) Pyruvate

C) Lactate and NAD+ These are the products of fermentation as it occurs in muscle cells.

In fermentation _____ is reduced and _____ is oxidized. A) NAD+ ... pyruvate B) Lactate ... ethanol C) Pyruvate ... NADH D) NADH ... lactate E) Lactate ... NADH

C) Pyruvate ... NADH The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

In the citric acid cycle, ATP molecules are produced by _____. A) Cellular respiration B) Oxidative phosphorylation C) Substrate-level phosphorylation D) Photosynthesis E) Photophosphorylation

C) Substrate-level phosphorylation A phosphate group is transferred from GTP to ADP.

In glycolysis there is a net gain of _____ ATP. A) 2 B) 1 C) 4 D) 5 E) 3

A) 2 It takes 2 ATP to produce 4 ATP.

How many oxygen molecules (O2) are required each time a molecule of glucose (C6H12O6) is completely oxidized to carbon dioxide and water via aerobic respiration? A) 30 B) 3 C) 6 D) 1 E) 12

C) 6

In glycolysis, what starts the process of glucose oxidation? A) NADPH B) ADP C) ATP D) FADH2 E) Hexokinase

C) ATP Some ATP energy is used to start the process of glucose oxidation.

Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the accompanying figure)? A) 38 ATP, 6 CO2, 3 NADH, and 12 FADH2 B) 1 ATP, 2 CO2, 3 NADH, and 1 FADH2 C) 3 ATP, 3 CO2, 3 NADH, and 3 FADH2 D) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2 E) 2 ATP, 2 CO2, 3 NADH, and 3 FADH2

D) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2

Which of these is NOT a product of the citric acid cycle? A) FADH2 D) Acetyl CoA C) CO2 D) NADH + H+ E) ATP

D) Acetyl CoA Acetyl CoA enters the citric acid cycle.

How many NADH are produced by glycolysis? A) 5 B) 1 C) 3 D) 4 E) 2

E) 2 Two NADH molecules are produced by glycolysis.

Glycolysis

Location: cytosol

In glycolysis, ATP molecules are produced by _____. A) Oxidative phosphorylation B) Substrate-level phosphorylation C) Photosynthesis D) Photophosphorylation E) Cellular respiration

B) Substrate-level phosphorylation A phosphate group is transferred from glyceraldehyde phosphate to ADP.

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A) It increases the surface for oxidative phosphorylation. B) It allows the liver cell to have more peroxisomes. C) It allows for an increased rate of the citric acid cycle. D) It allows for an increased rate of glycolysis. E) It increases the surface for substrate-level phosphorylation.

A) It increases the surface for oxidative phosphorylation.

What would happen to NADH levels in a cell in the first few seconds after a drug has poisoned the enzyme that combines acetyl CoA and oxaloacetate to form citrate? A) NADH levels would decrease. B) NADH levels would increase, then return to normal. C) NADH levels would remain unchanged D) NADH levels would increase.

A) NADH levels would decrease. 6 of 10 NADH molecules produced during glucose oxidation are products of the citric acid cycle.

Which metabolic pathway is common to both cellular respiration and fermentation? A) Chemiosmosis B) The citric acid cycle C) Glycolysis D) Oxidative phosphorylation E) The oxidation of pyruvate to acetyl CoA

C) Glycolysis

Each of the four stages of cellular respiration occurs in a specific location inside or outside the mitochondria. These locations permit precise regulation and partitioning of cellular resources to optimize the utilization of cellular energy. Match each stage of cellular respiration with the cellular location in which it occurs. Labels may be used once, more than once, or not at all.

Cellular respiration begins with glycolysis in the cytosol. Pyruvate, the product of glycolysis, then enters the mitochondrial matrix, crossing both the outer and inner membranes. Both acetyl CoA formation and the citric acid cycle take place in the matrix. The NADH and FADH2 produced during the first three stages release their electrons to the electron transport chain of oxidative phosphorylation at the inner mitochondrial membrane. The inner membrane provides the barrier that creates an H+ gradient during electron transport, which is used for ATP synthesis.

Which of these is NOT a product of glycolysis? A) NADH B) pyruvate C) ATP D) FADH2

D) FADH2 FADH2 is a product of the citric acid cycle.

After glucose is fully oxidized by glycolysis, pyruvate processing, and the citric acid cycle, where is most of the energy stored? A) In the form of FADH2 B) In the form of ATP C) In the electron transport chain D) In the form of NADH

D) In the form of NADH

During cellular respiration, acetyl CoA accumulates in which location? A) Cytosol B) Mitochondrial inner membrane C) Mitochondrial intermembrane space D) Mitochondrial matrix E) Mitochondrial outer membrane

D) Mitochondrial matrix

Which of the following would cause cells to switch from cellular respiration to fermentation? A) Pyruvate is not available. B) The proton-motive force runs down. C) NADH and FADH2 supplies are low. D) The final electron acceptor in the ETC is not available.

D) The final electron acceptor in the ETC is not available.

Which of these enters the citric acid cycle? A) NADH + H+ B) G3P C) Glucose D) Pyruvate E) Acetyl CoA

E) Acetyl CoA Acetyl CoA is a reactant in the citric acid cycle.

Oxidative phosphorylation

Location: inner mitochondrial membrane

Acetyl CoA formation

Location: mitochondrial matrix

Citric acid cycle

Location: mitochondrial matrix

In the citric acid cycle (also known as the Krebs cycle), acetyl CoA is completely oxidized. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of the citric acid cycle. Drag each compound to the appropriate bin. If a compound is not involved in the citric acid cycle, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of the citric acid cycle are included.)

Net input: Acetyl CoA NAD+ ADP Net output: NADH CO2 ATP Coenzyme A Not input ot output: Glucose O2 Pyruvate In the citric acid cycle, the two carbons from the acetyl group of acetyl CoA are oxidized to two molecules of CO2, while several molecules of NAD+ are reduced to NADH and one molecule of FAD is reduced to FADH2. In addition, one molecule of ATP is produced.

From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis. Drag each compound to the appropriate bin. If the compound is not involved in glycolysis, drag it to the "not input or output" bin.

Net input: Gluclose NAD+ ADP Net output: Pyruvate NADH ATP Not input or output: O2 CO2 Acetyl CoA Coenzyme A In glycolysis, the six-carbon sugar glucose is converted to two molecules of pyruvate (three carbons each), with the net production of 2 ATP and 2 NADH per glucose molecule. There is no O2 uptake or CO2 release in glycolysis.

In the last stage of cellular respiration, oxidative phosphorylation, all of the reduced electron carriers produced in the previous stages are oxidized by oxygen via the electron transport chain. The energy from this oxidation is stored in a form that is used by most other energy-requiring reactions in cells. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation. Drag each compound to the appropriate bin. If a compound is not involved in oxidative phosphorylation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of oxidative phosphorylation are listed.)

Net input: O2 ADP NADH Net output: NAD+ ATP Water Not input or output: CO2 Glucose Coenzyme A Acetyl CoA Pyruvate In oxidative phosphorylation, the NADH and FADH2 produced by the first three stages of cellular respiration are oxidized in the electron transport chain, reducing O2 to water and recycling NAD+ and FAD back to the first three stages of cellular respiration. The electron transport reactions supply the energy to drive most of a cell's ATP production.

In acetyl CoA formation, the carbon-containing compound from glycolysis is oxidized to produce acetyl CoA. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of acetyl CoA formation. Drag each compound to the appropriate bin. If a compound is not involved in acetyl CoA formation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of acetyl CoA formation are included.)

Net input: Pyruvate Coenzyme A NAD+ Net output: CO2 NADH Acetyl CoA Not input or output: ATP ADP Glucose O2 In acetyl CoA formation, pyruvate (a product of glycolysis) is oxidized to acetyl CoA, with the reduction of NAD+ to NADH and the release of one molecule of CO2.