Deck 10: Cell Respiration

Question 1

Which of the following types of metabolic poison would most directly interfere with glycolysis?

A) an agent that reacts with oxygen and depletes its concentration in the cell
B) an agent that binds to pyruvate and inactivates it
C) an agent that closely mimics the structure of glucose but is not metabolized
D) an agent that reacts with NADH and oxidizes it to NAD+

Answer 1

C

Question 2

Inhibition of which of the following metabolic pathways would result in decreased rates of CO₂ production?

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

Answer 2

B

Question 3

Depletion of which of the following molecules from the mitochondria will most directly inhibit the citric acid cycle?

A) NAD+
B) NADH
C) CO₂
D) ATP

Answer 3

A

Question 4

Which of the summary statements below best describes the results of the following reaction?
C6H12O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy

A) C6H12O₆ is oxidized and O₂ is reduced.
B) O₂ is oxidized and H₂O is reduced.
C) CO₂ is reduced and O₂ is oxidized.
D) O₂ is reduced and CO₂ is oxidized.

Question 5

In which reactions of cellular respiration does substrate-level phosphorylation occur?

A) only in glycolysis
B) only in the citric acid cycle
C) only in the electron transport chain
D) in both glycolysis and the citric acid cycle

Question 6

A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply?

A) The athlete will have to sit down and rest.
B) Catabolic processes will be activated to generate additional ATP.
C) ATP will be transported into the cells from the circulatory system.
D) Anabolic processes will be activated to produce new mitochondria.

Question 7

Upon completion of the citric acid cycle, most of the energy originally stored in each glucose molecule catabolized by cellular respiration is stored in which of the following molecules?

A) acetyl-CoA
B) ATP
C) CO₂
D) NADH

Question 8

Which of the following reactions produces the majority of the CO₂ released by the complete oxidation of glucose?

A) glycolysis
B) electron transport
C) oxidation of pyruvate to acetyl-CoA
D) the citric acid cycle

Question 9

Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom?

A) NAD+ becomes dehydrogenated.
B) NAD+ becomes oxidized.
C) NAD+ becomes reduced.
D) NAD+ becomes ionized.

Question 10

Which of the following statements best describes how a reducing agent in is chemically altered in a biological redox reaction?

A) It gains a hydrogen atom and gains potential energy.
B) It loses a hydrogen atom and loses potential energy.
C) It gains a hydrogen atom and loses potential energy.
D) It loses a hydrogen atom and gains potential energy.

Question 11

When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is ________.

A) hydrolyzed
B) an oxidizing agent
C) oxidized
D) reduced

Question 12

If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA?

A) 1/6
B) 1/3
C) 2/3
D) 100%

Question 13

The citric acid cycle.
Which of the following is the most likely effect on the rates of ATP and CO₂ production if yeast cells growing in minimal medium lacking glucose are provided with supplemental acetyl-CoA?

A) There would be no change in ATP production, but the rate of carbon dioxide production would increase.
B) The rates of ATP production and carbon dioxide production would both increase.
C) The rate of ATP production would increase, but the rate of carbon dioxide production would decrease.
D) The rates of ATP and carbon dioxide production would both decrease.

Question 14

The standard free energy for the complete oxidation of glucose to CO₂ and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced?

A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.
B) Glycolysis is a very inefficient process, with much of the energy of glucose released as heat.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
D) There is no CO₂ or water produced as products of glycolysis.

Question 15

Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods?

A) They contain many protons associated with oxygen atoms.
B) They contain no low-energy nitrogen atoms.
C) They contain many electrons associated with hydrogen atoms.
D) They are strong oxidizing molecules.

Question 16

Which of the following statements best describes a characteristic of NAD+?

A) NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.
B) NAD+ stores more chemical energy than NADH.
C) NAD+ may donate electrons for use in oxidative phosphorylation.
D) NAD+ is oxidized in glycolysis to produce ATP.

Question 17

Which of the following statements best summarizes ATP use and production in the catabolism of each glucose molecule in glycolysis?

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) four molecules of ATP are used, and four molecules of ATP are produced

Question 18

When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________.

A) reduced, and energy is released
B) reduced, and energy is used
C) oxidized, and energy is used
D) oxidized, and energy is released

Question 19

Substrate-level phosphorylation accounts for approximately what percent of the ATP formed by the reactions of glycolysis?

A) 0%
B) 2%
C) 38%
D) 100%

Question 20

Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?

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

Question 21

Which of the following products result from the oxidation of pyruvate to acetyl-CoA?

A) O₂ and ATP
B) FADH₂ and CO₂
C) NADH and CO₂
D) NAD+, ATP and CO₂

Question 22

Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO₂) from a molecule of pyruvate?

A) ATP
B) acetyl CoA
C) citrate
D) water

Question 23

The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes?

A) active transport
B) allosteric regulation
C) a reaction with a positive ΔG
D) coupling of an endergonic reaction to an exergonic reaction

Question 24

Which of the following statements best describes the electron transport chain?

A) It is driven by ATP hydrolysis.
B) It includes a series of hydrolysis reactions associated with mitochondrial membranes.
C) It consists of a series of redox reactions.
D) It occurs in the cytoplasm of both prokaryotic and eukaryotic cells.

Question 25

If the proteins of the electron transport chain were labeled with a fluorescent tag, the fluorescence observed by microscopy will be localized to which of the following regions of the mitochondria?

A) outer membrane
B) inner membrane
C) intermembrane space
D) matrix

Question 26

If a cell produces on average 30 ATP molecules for each molecule of glucose that is completely oxidized to carbon dioxide and water, how many ATP molecules on average can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?

A) 8
B) 12.5
C) 14
D) 25

Question 27

Which of the following processes is driven by chemiosmosis?

A) substrate-level phosphorylation
B) oxidative phosphorylation
C) ATP hydrolysis
D) reduction of NAD+ to NADH

Question 28

When a cell is deprived of oxygen, which of the following processes will be inhibited first?

A) glycolysis
B) the electron transport chain
C) the citric acid cycle
D) the oxidation of pyruvate to acetyl CoA

Question 29

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O₆) in aerobic cellular respiration?

A) 2
B) 4
C) 18-24
D) 30-32

Question 30

Which of the following sequences describes the path by which electrons move from high-energy to lower-energy molecules in aerobic respiration?

A) glucose → NADH → electron transport chain → oxygen
B) glucose → pyruvate → ATP → oxygen
C) glucose → pyruvate → electron transport chain → NADH → ATP
D) food → glycolysis → citric acid cycle → NADH → ATP

Question 31

The citric acid cycle.
Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?

A) 1 ATP, 2 CO₂, 3 NADH, and 1 FADH₂
B) 3 ATP, 3 CO₂, 3 NADH, and 3 FADH₂
C) 3 ATP, 6 CO₂, 9 NADH, and 3 FADH₂
D) 6 ATP, 6 CO₂, 3 NADH, and 12 FADH₂

Question 32

Which of the following events takes place in the electron transport chain?

A) the breakdown of glucose into six carbon dioxide molecules
B) the breakdown of an acetyl group to carbon dioxide
C) the harnessing of energy from redox reactions to generate a proton gradient
D) substrate-level phosphorylation

Question 33

Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?

A) cytoplasm adjacent to the mitochondrial outer membrane
B) mitochondrial inner membrane
C) mitochondrial intermembrane space
D) mitochondrial matrix

Question 34

Which of the following statements best describes the primary role played by oxygen in cellular respiration?

A) It yields energy in the form of ATP as it is passed down the electron transport chain.
B) It oxidizes glucose to form two molecules of pyruvate.
C) It serves as an acceptor for carbon, forming CO₂ in the citric acid cycle.
D) It serves as the final acceptor for electrons from the electron transport chain.

Question 35

The citric acid cycle.
If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure?

A) Oxaloacetate will decrease and citrate will accumulate.
B) Oxaloacetate will accumulate and citrate will decrease.
C) Both oxaloacetate and citrate will decrease.
D) Both oxaloacetate and citrate will accumulate.

Question 36

Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain?

A) NADH
B) ATP
C) water
D) FADH₂

Question 37

In chemiosmosis, the most direct source of energy used to convert ADP + i to ATP is energy released ________.

A) as electrons flow through the electron transport chain
B) from substrate-level phosphorylation
C) from movement of protons through ATP synthase, down their electrochemical gradient
D) as electrons are transported across the inner mitochondrial membrane

Question 38

Inhibition of which of the following processes would reduce or eliminate generation of a proton-motive force in mitochondria?

A) the flow of protons through ATP synthase down their concentration gradient
B) the reduction of NAD+ by the first electron carrier in the electron transport chain
C) lowering of pH in the mitochondrial matrix
D) pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space

Question 39

Assume that it is possible to label each of the molecules below with 18O a heavy isotope of oxygen. As a result of cellular respiration, water containing 18O would most quickly be detected if cells are provided with which one of the following molecules labeled with 18O?

A) carbon dioxide (CO₂)
B) glucose (C6H12O₆)
C) molecular oxygen (O₂)
D) pyruvate (C3H3O3)

Question 40

The citric acid cycle.
For each mole of glucose (C6H12O₆) oxidized by cellular respiration, how many moles of CO₂ are released in the citric acid cycle (see the accompanying figure)?

A) 2
B) 4
C) 6
D) 32

Question 41

What types of cells carry out ATP synthesis by chemiosmosis?

A) all cells, both prokaryotic and eukaryotic, exclusively using oxygen as the electron acceptor
B) only animal cells in mitochondria, exclusively using oxygen as the electron acceptor
C) only eukaryotic cells, both plant and animal, using either oxygen or other electron acceptors
D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

Question 42

In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules?

A) ATP, CO₂, and ethanol
B) ATP, CO₂, and lactate
C) ATP, NADH, and ethanol
D) ATP, CO₂, and acetyl CoA

Question 43

A 3-year old dog has never been able to tolerate much physical activity. A veterinarian discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and its muscle cells produce elevated levels of lactate. Which of the following statements best explains the dog's condition?

A) Its cells cannot transport pyruvate from the cytosol into the mitochondria.
B) Its cells cannot transport NADH from glycolysis into the mitochondria.
C) Its cells cannot complete glycolysis.
D) Its cells have a defective electron transport chain, so glucose is metabolized to lactate instead of to acetyl CoA.

Question 44

In liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased rates of which process below?

A) glycolysis
B) the citric acid cycle
C) oxidative phosphorylation
D) substrate-level phosphorylation

Question 45

High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location than the active site. This is an example of which of the following?

A) competitive inhibition
B) allosteric regulation
C) the specificity of enzymes for their substrates
D) positive feedback regulation

Question 46

Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?

A) reduction of NAD+ to NADH
B) reduction of FAD to FADH₂
C) oxidation of NADH to NAD+
D) hydrolysis of ATP to ADP + i

Question 47

Which of the following statements best supports the claim that glycolysis is likely one of the first metabolic pathways to have evolved?

A) It produces much less ATP than does oxidative phosphorylation.
B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
C) It is present in prokaryotic cells but not in eukaryotic cells.
D) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.

Question 48

In the following reaction which molecule functions as the oxidizing agent?
Pyruvate + NADH + H+ → Lactate + NAD+

A) NADH
B) NAD+
C) lactate
D) pyruvate

Question 49

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal to form small vesicles that contain the intermembrane space. These vesicles can transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements best describes what will happen to the vesicles when NADH is added?

A) The inside of the vesicles will become acidic.
B) The inside of the vesicles will become alkaline.
C) ATP will be produced from ADP and i in the interior of the vesicle.
D) Protons will be pumped out of the interior of the vesicle to the exterior using energy from ATP hydrolysis.

Question 50

Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present?

A) only the electron transport system
B) only the ATP synthase system
C) all of the electron transport system and the proteins that add CoA to acetyl groups
D) all of the electron transport system and ATP synthase

Question 51

Which of the following best predicts the effect of removal of oxygen from a facultative anaerobic organism's environment?

A) glucose consumption increases, while the growth rate decreases
B) glucose consumption and the growth rate both increase
C) glucose consumption decreases, while the growth rate increases
D) glucose consumption decreases, while the growth rate remains unchanged

Question 52

New biosensors, applied like a temporary tattoo to the skin, can alert endurance athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate present in sweat during strenuous exercise. Which of the statements below best explains the use of lactate as an indicator of exercise capacity?

A) During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions, and muscles begin to cramp, thus athletic performance suffers.
B) During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
C) During aerobic respiration, muscles cells produce too much lactate, which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH.
D) During anaerobic respiration, muscle cells receive too little oxygen and begin to convert lactate to pyruvate (pyruvic acid), thus athletes experience cramping and fatigue.

Question 53

Beta oxidation generates substrates for cellular respiration through catabolism of which of the following molecules?

A) glucose
B) glycogen
C) proteins
D) fatty acids

Question 54

Which of the following metabolic processes take place in the cytosol of a eukaryotic cell?

A) glycolysis and fermentation
B) fermentation and chemiosmosis
C) oxidation of pyruvate to acetyl CoA
D) citric acid cycle

Question 55

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Dogs affected with this disorder most likely display which of the following symptoms?

A) They die as embryos.
B) They constantly have low blood sugar.
C) They are lethargic and readily tire from exercise.
D) They carry out elevated levels of oxidative phosphorylation.

Question 56

Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O₂) availability?

A) citric acid cycle
B) glycolysis
C) lactate fermentation
D) oxidative phosphorylation

Question 57

Yeast cells with defective mitochondria that are incapable of performing cellular respiration will be able to survive by using which of the following molecules for energy?

A) glucose
B) cholesterol
C) fatty acids
D) amino acids

Question 58

The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules?

A) glucose and NAD+
B) AMP and ATP
C) ATP and citrate
D) citrate and CO₂

Question 59

Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation?

A) only in photosynthetic cells in the light, while photosynthesis occurs concurrently
B) only in cells that store glucose in the form of starch and only in the dark
C) in all cells, with or without light
D) in photosynthesizing cells in the light, and in other cells in the dark

Question 60

A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body?

A) released as CO₂ and H₂O
B) converted to heat and then released
C) converted to ATP, which weighs much less than fat
D) eliminated from the body as feces

Question 61

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 carbon atoms to carbon dioxide
D) are coupled via phosphorylated intermediates to endergonic processes

Question 62

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

A) O₂
B) water
C) NAD+
D) pyruvate

Question 63

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.

Question 64

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 ATPsynthase
D) transfer of phosphate to ADP

Question 65

Most CO₂ from catabolism is released during ________.

A) glycolysis
B) the citric acid cycle
C) lactate fermentation
D) electron transport

Question 66

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

Question 67

What is the oxidizing agent in the following reaction?
Pyruvate + NADH + H+ → Lactate + NAD+

A) oxygen
B) NADH
C) lactate
D) pyruvate

Question 68

Catabolism of fatty acids produces two-carbon molecules that are converted to acetyl CoA. The acetyl CoA molecules will most likely be metabolized in aerobic cellular respiration by which of the following mechanisms?

A) directly entering the electron transport chain
B) directly entering the energy-yielding phase of glycolysis
C) being converted to pyruvate and then undergo pyruvate oxidation upon transport into mitochondria
D) directly entering the citric acid cycle