Deck 7: Cellular Respiration: Harvesting Energy From Carbohydrates and Other Fuel Molecules

Question 1

When carbohydrates are oxidized, the C-H bonds of the carbohydrate become C=O bonds of carbon dioxide. Oxidation is defined as a loss of electrons, but carbon does not become positively charged in the process. Why then is this considered oxidation?

A)The shared electrons in C-O bonds spend less time close to the carbon nucleus than the shared electrons in C-H bonds.
B)Electrons in the C=O bonds are higher energy than the electrons in the C-H bonds.
C)C=O bonds in CO₂ are double bonds, and C-H bonds are single bonds.
D)The phosphate groups of ATP are ionized, and carbons donate those electrons.

Answer 1

A

Question 2

Why do marathon runners "carbo load" (that is, eat a lot of pasta) before a big race?

A)They will feel full longer.
B)The bonds in carbohydrates have high potential energy.
C)The bonds in carbohydrates have low potential energy and can thus be broken down and readily consumed.
D)Through the process of anabolism, the athlete will break down the carbohydrates into smaller components, including ATP.

Answer 2

B

Question 3

Which one of the following represents the REDUCED forms of the two major electron carriers?

A)NAD⁺ and FAD
B)NAD⁺ and FADH₂
C)NADH and FAD
D)NADH and FADH₂

Answer 3

D

Question 4

The approximate yield of ATP molecules from the full oxidation of a molecule of glucose is:

A)2)
B)6)
C)12.
D)32.
E)64.

Question 5

Which one of the following is NOT a product of cellular respiration?

A)carbon dioxide
B)water
C)oxygen
D)ATP
E)All of these choices are correct.

Question 6

Are electrons lost or gained in reduction?

A)lost
B)gained

Question 7

The MOST stablethat is, least reactiveform of carbon is:

A)ethanol.
B)diamond.
C)glucose.
D)pyruvate.
E)carbon dioxide.

Question 8

Some tissue types like brain tissue use glucose exclusively as an energy source.

Question 9

The rate of cellular respiration is constant in plants and animals, including humans.

Question 10

Consulting Figure 7.3 if necessary, during which stage(s) of cellular respiration is carbon dioxide released?

A)stage 1 only
B)stages 1 and 2
C)stages 2 and 3
D)stage 3 only
E)stages 3 and 4

Question 11

The energy in organic molecules is released in a series of steps because:

A)it is not possible to release it in a single step.
B)more total energy is released in multiple steps than would be released in a single step.
C)less total energy is released in multiple steps than would be released in a single step.
D)more energy can be harvested for cellular use in multiple steps than from a single step.
E)only a single electron can be moved at a time in a cellular reaction.

Question 12

Kangaroo rats live in the desert of the southwestern United States. They have many adaptations to minimize water loss. They obtain a small amount of water from seeds that they eat. However, the rest of the water they obtain is from cellular respiration.

A)This cannot be true, as cellular respiration doesn't really "produce" water.
B)This cannot be true, as water is actually consumed in cellular respiration.
C)This could be true, as water is produced in cellular respiration.
D)This could be true, as water is produced in glycolysis.
E)This could be true, as water is produced in the citric acid cycle.

Question 13

An organism that carries out cellular respiration in its mitochondria:

A)may be a cell from a terrestrial (land)plant.
B)may be a prokaryotic cell from the domain Archaea.
C)is a bacterium.
D)may be any kind of cell.

Question 14

Complete oxidation of glucose to CO₂ involves two different mechanisms for synthesizing ATP: oxidative phosphorylation and substrate-level phosphorylation. Which is TRUE of substrate-level phosphorylation?

A)An enzyme catalyzes the transfer of a phosphate group to ADP from an organic molecule to form ATP.
B)Most of the ATP generated in cellular respiration is generated by substrate-level phosphorylation.
C)ATP is generated indirectly through the transfer of high-energy electrons from electron carriers to an electron transport chain.
D)ATP is generated by release of energy from the electron carriers NADH and FADH₂.

Question 15

Energy can be extracted from glucose and converted to ATP only if:

A)oxygen is the electron acceptor.
B)the cell has mitochondria.
C)the cell has membrane proteins that can pump hydrogen ions.
D)the cell has enzymes that can carry out oxidation-reduction reactions.
E)the cell has enzymes that can carry out glycolysis.

Question 16

In the reactions of glycolysis, pyruvate oxidation, and the citric acid cycle, chemical energy is transferred to the bonds in:

A)ATP.
B)electron carriers.
C)fats.
D)All of these choices are correct.

Question 17

Which of the following molecules has the GREATEST potential energy?

A)glucose
B)water
C)carbon dioxide

Question 18

Cellular respiration releases energy. In cellular respiration:

A)organic molecules such as carbohydrates are converted to chemical energy that can be used to do the work of the cell.
B)the chemical potential energy stored in organic molecules is converted to chemical energy that can be used to do the work of the cell.
C)chemical potential energy in the bonds of ADP is transferred to the chemical potential energy in the bonds of ATP.

Question 19

Which is NOT a stage of cellular respiration?

A)citric acid cycle
B)glycolysis
C)oxidative phosphorylation
D)photosynthesis

Question 20

In which form are electrons transferred during typical redox reactions such as the oxidation of glucose?

A)as free electrons
B)as hydrogen atoms
C)as oxygen atoms
D)as carbon atoms
E)as phosphate groups

Question 21

The gain of electrons is referred to as _____.

Question 22

Which of the following statements is TREUE regarding a reducing agent?

A)It loses electrons.
B)It gains electrons.
C)It is an electron acceptor.
D)It is usually oxygen.
E)It is never oxidized.

Question 23

Which stage of cellular respiration occurs immediately after pyruvate is produced?

A)glycolysis
B)pyruvate oxidation
C)citric acid cycle
D)electron transport
E)oxidative phosphorylation

Question 24

Which of the following statements is TRUE regarding aerobic respiration?

A)Aerobic respiration requires oxygen at every stage of the process.
B)Aerobic respiration is carried out by all prokaryotes and eukaryotes.
C)Aerobic respiration is a three-stage process, with oxidative phosphorylation comprising the last stage.
D)Carbon dioxide is produced at every stage of aerobic respiration.
E)None of the other answer options is correct.

Question 25

Glycolysis is a series of chemical reactions (endergonic and exergonic) by which the cell can obtain ATP. NAD⁺ plays a crucial role in the reactions of glycolysis by:

A)accepting electrons from glucose, with the result that glucose is partially oxidized to pyruvate.
B)donating electrons to pyruvate when glucose becomes partially oxidized.
C)converting endergonic reactions to exergonic reactions so that there is an output of energy to make ATP.
D)donating electrons to ADP to make ATP.

Question 26

Cellular respiration is a series of _____ reactions.

A)catabolic
B)anabolic
C)glycolytic
D)phosphorylation
E)carboxylation

Question 27

In a plant cell, all stages of cellular respiration are carried out in the cytoplasm.

Question 28

In the first three stages of cellular respiration, the chemical energy in glucose is transferred to:

A)ATP and cytochrome b.
B)electron carriers and ATP.
C)cytochrome b and coenzyme Q.
D)proton pumps and ATP.
E)only coenzyme Q.

Question 29

The loss of electrons is referred to as _____.

Question 30

In cellular respiration, glucose is _____ to CO₂ and oxygen is _____ to water.

A)oxidized; reduced
B)reduced; oxidized
C)deoxygenated; phosphorylated
D)phosphorylated; deoxygenated
E)oxidized; oxidized

Question 31

Which of the following statements is TRUE regarding the equation C₆H₁₂O₆ + 6O₂  6CO₂ + 6H₂O + energy?

A)The oxygen atoms in both CO₂ and H₂O are electronegative.
B)In the production of CO₂ from glucose, the oxygen atoms lose electrons and the carbon atom is oxidized.
C)Glucose could be considered a reducing agent.
D)The movement of hydrogen atoms in reactions involving C₆H₁₂O₆ and H₂O yields no information regarding the movement of electrons.
E)The oxygen atoms in both CO₂ and H₂O are electronegative, and glucose is considered a reducing agent.

Question 32

When glucose is broken down in a cell, all of the energy it stores is released simultaneously, not in a stepwise process.

Question 33

The chemical bonds of carbohydrates and lipids have high potential energy because:

A)they are strong oxidizing agents.
B)they are strong reducing agents.
C)many of these bonds are C-C and C-H bonds.
D)they are easy to phosphorylate.
E)they are easy to hydrolyze.

Question 34

You are trying to find the maximum source of energy for an organism. Which of the following compounds would you choose?

A)glucose
B)oxygen
C)ATP
D)pyruvate
E)NADH

Question 35

A molecule that is _____ loses electrons, and a molecule that is _____ gains electrons.

A)reduced; oxidized
B)negative; positive
C)oxidized; reduced
D)weak; polar
E)None of the other answer options is correct.

Question 36

The electron transport chain is part of:

A)glycolysis.
B)the citric acid cycle.
C)oxidative phosphorylation.
D)fermentation.
E)pyruvate oxidation.

Question 37

The _____ forms of the electron carriers NAD⁺/NADH and FADH/FADH₂ have high potential energy.

A)oxidized
B)reduced
C)phosphorylated
D)carboxylated
E)None of the other answer options is correct.

Question 38

Oxidation is the gain of electrons.

Question 39

Which BEST describes energy production during cellular respiration?

A)A small amount of energy is produced by substrate-level phosphorylation; most is produced by oxidative phosphorylation.
B)A small amount of energy is produced by oxidative phosphorylation; most is produced by substrate-level phosphorylation.
C)An equal amount is produced by oxidative phosphorylation and substrate-level phosphorylation.
D)It depends on the organism. Some produce most of their energy by substrate-level phosphorylation, and some produce most of their energy by oxidative phosphorylation.
E)None of the other answer options is correct.

Question 40

In cellular respiration, oxygen:

A)gains electrons and is an oxidizing agent.
B)loses electrons and is a reducing agent.
C)gains electrons and is a reducing agent.
D)loses electrons and is an oxidizing agent.
E)None of the other answer options is correct.

Question 41

The first phase of glycolysis requires the input of two ATP molecules. It is therefore:

A)endergonic.
B)exergonic.
C)oxidative.
D)reducing.
E)None of the other answer options is correct.

Question 42

How many reactions in glycolysis directly generate ATP?

A)1
B)2
C)3
D)4
E)5

Question 43

In eukaryotic cells, glycolysis occurs in:

A)the cytoplasm.
B)the nucleus.
C)the matrix of the mitochondria.
D)the endoplasmic reticulum.
E)vacuoles.

Question 44

At the end of glycolysis, the carbon molecules originally found in the starting glucose molecule are in the form of:

A)one pyruvate molecule.
B)two pyruvate molecules.
C)two ATP molecules.
D)two NADH molecules.
E)four ATP molecules.

Question 45

Although cellular respiration is typically thought of as an aerobic process, glycolysis itself is actually anaerobic.

Question 46

The phosphorylation of glucose during glycolysis serves to:

A)destabilize the molecule, making it easier to cleave.
B)trap imported glucose inside the cell.
C)reduce an electron carrier, storing energy for later.

Question 47

How did the earliest organisms on Earth most likely produce ATP?

A)by pyruvate oxidation
B)by glycolysis
C)by the citric acid cycle
D)by oxidative phosphorylation

Question 48

The ATP produced during glycolysis is the result of substrate-level phosphorylation.

Question 49

In the second phase of glycolysis:

A)phosphate groups are added to glucose.
B)phosphorylated sugar molecule is cleaved and the products rearranged.
C)ATP is generated by substrate-level phosphorylation.
D)NAD⁺ is reduced to NADH.
E)ATP is generated by oxidative phosphorylation.

Question 50

During what phase of glycolysis is NADH formed?

A)during phase 1, when fructose 1,6-biphosphate is formed
B)during phase 2, when glyceraldehyde 3-phosphate is formed
C)during phase 3, when glyceraldehyde 3-phosphate is phosphorylated
D)during phase 3, when pyruvate is finally formed
E)during phase 1, when glucose is phosphorylated

Question 51

Even though the full oxidation of glucose is exergonic, some of the reactions in cellular respiration are endergonic.

Question 52

Imagine that a eukaryotic cell carries a mutation impairing its ability to phosphorylate glucose during glycolysis. What is a likely result of this mutation?

A)High (possibly toxic)levels of glucose would accumulate in the cell.
B)Glucose could move out of the cell, slowing cellular respiration.
C)Because phosphorylation stabilizes glucose, glucose would spontaneously form pyruvate.
D)Without the phosphorylation of glucose, glycolysis would consist entirely of exergonic reactions.
E)More pyruvate would be formed at the end of glycolysis.

Question 53

Which of the following is NOT one of the net final products of glycolysis?

A)two molecules of pyruvate
B)two molecules of ATP
C)two molecules of NADH
D)two molecules of acetyl-CoA

Question 54

Glycolysis is:

A)aerobic.
B)anaerobic.
C)aerobic in some organisms but anaerobic in others.
D)aerobic in some tissues but anaerobic in others.
E)None of the other answer options is correct.

Question 55

In glycolysis, ATP is synthesized by:

A)substrate-level phosphorylation.
B)oxidative phosphorylation.
C)both substrate level and oxidative phosphorylation.
D)electron carriers.
E)redox reactions.

Question 56

The inputs to glycolysis do NOT include:

A)glucose.
B)NAD⁺.
C)NADH.
D)ADP.
E)P_i.

Question 57

Phosphorylating glucose during phase 1 of glycolysis:

A)releases phosphorylated glucose from cells.
B)destabilizes the glucose molecule so that it can be broken down in phase 2.
C)provides electrons to reduce NAD⁺ in phase 3.
D)provides electrons to reduce FADH in phase 3.
E)None of the other answer options is correct.

Question 58

Which of the following is a net product of glycolysis?

A)2 pyruvate
B)2 ATP
C)2 NADH

Question 59

Which of the following does NOT occur during the third phase of glycolysis?

A)pyruvate production
B)ATP synthesis
C)the transfer of high-energy electrons to NAD⁺
D)oxygen consumption
E)None of the other answer options is correct.

Question 60

Although glycolysis produces four molecules of ATP by substrate-level phosphorylation, the net gain of ATP for the cell is two molecules. This is due to the fact that glycolysis is-at first-endergonic.

Question 61

After pyruvate oxidation, the chemical energy of how many carbons of the original glucose molecule is converted to chemical energy in the form of ATP in the remaining steps of cellular respiration?

A)1
B)2
C)3
D)4
E)5

Question 62

Which of the following statements is TRUE regarding pyruvate and glucose?

A)Glucose easily passes in and out of mitochondria, and can often be found in the mitochondrial matrix.
B)Pyruvate is typically "trapped" in the intermembrane space of mitochondria, where it is oxidized to form acetyl-CoA.
C)Glucose and pyruvate are remarkably similar in structure, with both molecules possessing a ring shape.
D)Both glucose and pyruvate can feed directly into the citric acid cycle, although acetyl-CoA is the preferred reactant for this process.
E)None of the other answer options is correct.

Question 63

In the reaction in the diagram below, pyruvate is converted to acetyl-CoA. Which if any of the following statements concerning this reaction is TRUE?

A)CO₂ is the most oxidized and therefore least energetic form of carbon.
B)NAD⁺ is more reduced than NADH.
C)NAD⁺ is an oxidizing agent.
D)This is not an oxidation/reduction reaction; that is, no electrons have moved.
E)This reaction harnesses the last of the remaining potential energy from glucose.

Question 64

During pyruvate oxidation, which of the following also occur(s)?

A)the formation of NADH
B)the oxidation of pyruvate
C)the formation of acetyl-CoA
D)the formation of CO₂
E)All of these choices are correct.

Question 65

What is the relationship between the reaction diagrammed here and glycolysis?

Question 66

During pyruvate oxidation, pyruvate is broken down into CO₂ and an acetyl group. The CO₂ is _____ than the acetyl group.

A)less oxidized
B)more reduced
C)more energetic
D)less energetic
E)None of the other answer options is correct.

Question 67

In eukaryotes, pyruvate oxidation takes place in the:

A)cytoplasm.
B)outer mitochondrial membrane.
C)inner mitochondrial membrane.
D)intermembrane space of mitochondria.
E)mitochondrial matrix.

Question 68

In eukaryotic cells, the oxidation of pyruvate occurs in:

A)the cytoplasm.
B)the nucleus.
C)the matrix of the mitochondria.
D)the endoplasmic reticulum.
E)vacuoles.

Question 69

Another name for acetyl-CoA synthesis is:

A)glycolysis.
B)pyruvate oxidation.
C)oxidative phosphorylation.
D)substrate-level phosphorylation.
E)pyruvate reduction.

Question 70

The conversion of pyruvate to acetyl-CoA does not produce any ATP directly. However, it does contribute to ATP production indirectly. How?

Question 71

In what organelle is pyruvate oxidation carried out in a cell?

A)chloroplast
B)nucleus
C)mitochondrion
D)Golgi apparatus
E)endoplasmic reticulum

Question 72

Which of the following statements is TRUE regarding pyruvate oxidation?

A)Like glycolysis, pyruvate oxidation is carried out in the mitochondria.
B)Pyruvate oxidation ends with the oxidation of an acetyl group, which forms CO₂.
C)Pyruvate oxidation forms the same number of NADH (per glucose molecule)as glycolysis.
D)Pyruvate oxidation directly follows the citric acid cycle during cellular respiration.

Question 73

Pyruvate oxidation is an important stage in cellular respiration because it:

A)generates ATP by substrate-level phosphorylation.
B)transfers large numbers of electrons to electron carriers.
C)links glycolysis with the citric acid cycle.
D)eliminates toxic pyruvate from the cell.
E)is the first step in oxidative phosphorylation.

Question 74

When a single pyruvate is converted to acetyl-CoA, the other products of the reaction are:

A)CO₂ and ATP.
B)NADH and CO₂.
C)ATP and NADH.
D)P_i and FADH₂.
E)FADH₂ and ATP.

Question 75

What glycolysis product is transported into the mitochondria?

A)ATP
B)NADP
C)pyruvate
D)glucose

Question 76

Like glycolysis, pyruvate oxidation produces both pyruvate and acetyl-CoA. These two products feed directly into the citric acid cycle and are the reactants for the cycle.

Question 77

By the time pyruvate is formed, most of the energy contained in glucose has been released.

Question 78

Pyruvate oxidation produces a large amount of ATP.

Question 79

Pyruvate oxidation is remarkably similar to glycolysis in that when one molecule of pyruvate enters into a mitochondrion, two molecules of acetyl-CoA are formed.

Question 80

What is the relationship between the reaction diagrammed below and the citric acid cycle?