Deck 6: Pathways That Harvest and Store Chemical Energy

Question 1

The function of NAD⁺ is to

A) cause the release of energy to adjacent cells when energy is needed in aerobic conditions.
B) hasten the release of energy when the cell has been deprived of oxygen.
C) carry hydrogen atoms and free energy from compounds being oxidized,and to give hydrogen atoms and free energy to compounds being reduced.
D) block the release of energy to adjacent cells.
E) convert the potential energy of the proton gradient into the chemical energy in ATP.

Answer 1

C

Question 2

Which statement about NAD is true?

A) It is a key electron carrier in redox reactions.
B) It requires oxygen to function.
C) It is found only in prokaryotes.
D) It binds with an acetyl group to form acetyl CoA.
E) It detoxifies hydrogen peroxide.

Answer 2

A

Question 3

The process that converts glucose to pyruvate,generating a small amount of ATP but no carbon dioxide,is called

A) pyruvate oxidation.
B) glycolysis.
C) the citric acid cycle.
D) the respiratory chain.
E) gluconeogenesis.

Answer 3

B

Question 4

During glycolysis,for each mole of glucose oxidized to pyruvate,_______ is/are produced.

A) 6 moles of ATP
B) 2 moles of ATP
C) 4 moles of ATP
D) 2 moles of NAD⁺
E) no ATP

Question 5

Which statement about pyruvate is false?

A) It is the end product of glycolysis.
B) It becomes reduced during fermentation.
C) It is a precursor of acetyl CoA.
D) It is a protein.
E) It contains three carbon atoms.

Question 6

The role of oxygen gas in our cells is to

A) catalyze reactions in glycolysis.
B) produce CO₂.
C) form ATP.
D) accept electrons from the respiratory chain.
E) react with glucose to split water.

Question 7

When a molecule loses hydrogen atoms (as opposed to hydrogen ions),it becomes

A) reduced.
B) oxidized.
C) redoxed.
D) hydrogenated.
E) hydrolyzed.

Question 8

Glycolysis

A) takes place in the mitochondrion.
B) produces no ATP.
C) has no connection with the respiratory chain.
D) is the same thing as fermentation.
E) reduces two molecules of NAD⁺ for every glucose molecule processed.

Question 9

When ADP gains a phosphate to form ATP,

A) free energy is released by the loss of a phosphate.
B) energy is consumed.
C) the reaction ends.
D) chemical energy is converted to light energy.
E) ribose loses an oxygen to become deoxyribose.

Question 10

Which statement about metabolic pathways is false?

A) The product of one reaction becomes the reactant for the next reaction.
B) They are a series of enzyme-catalyzed reactions.
C) Almost all are endergonic.
D) They are similar in all organisms.
E) Many are compartmentalized in eukaryotes.

Question 11

The exergonic reaction 1,3-diphosphoglycerate $\rightarrow$ 3-phosphoglycerate is coupled to the reaction ADP + P_i $\rightarrow$ ATP.Which of the following is most likely to be true about the reaction ADP + P_i $\rightarrow$ ATP?

A) The reaction never reaches equilibrium.
B) The reaction is spontaneous.
C) There is a large decrease in free energy.
D) The reaction is endergonic.
E) Temperature will not affect the rate constant of the reaction.

Question 12

Phosphorylation of ADP to ATP is endergonic,whereas the hydrolysis of ATP to ADP is exergonic.The two reactions are therefore said to be

A) substrates.
B) endergonic.
C) kinetic.
D) activated.
E) coupled.

Question 13

Which statement about ATP is true?

A) It is an energy-storage compound.
B) It is the cell's principal compound for energy transfers.
C) It stands for adenosine triphosphate.
D) It is the molecule all living cells rely on to do chemical work.
E) All of the above

Question 14

Animals inhale air containing oxygen and exhale air with less oxygen and more carbon dioxide.After inhalation,the oxygen missing from the air will mostly be found in

A) the carbon dioxide that is exhaled.
B) water.
C) organic molecules.
D) ethanol.
E) lactate.

Question 15

When NADH donates two electrons to ubiquinone during respiration,ubiquinone is

A) reduced.
B) oxidized.
C) phosphorylated.
D) aerobic.
E) hydrolyzed.

Question 16

Oxidation and reduction

A) entail the gain or loss of proteins.
B) are defined as the loss of electrons.
C) are both endergonic reactions.
D) always occur together.
E) proceed only under aerobic conditions.

Question 17

The proton motive force is

A) ATP synthase.
B) the proton concentration gradient and electric charge difference.
C) a metabolic pathway.
D) a redox reaction.
E) the movement of electrons across the membrane.

Question 18

Which statement about metabolic pathways is true?

A) Complex chemical transformations in the cell occur in a single reaction.
B) Each reaction requires ATP.
C) In eukaryotes,they occur in the cytoplasm.
D) They vary from organism to organism.
E) Each one is regulated by specific enzymes.

Question 19

Which statement about oxidative phosphorylation is false?

A) It forms ATP by the respiratory chain/ATP synthesis.
B) It is brought about by chemiosmosis.
C) It requires aerobic conditions.
D) It takes place in mitochondria.
E) Its functions can be served equally well by fermentation.

Question 20

In all cells,glucose metabolism begins with

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

Question 21

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane into the intermembranous space,the result is the

A) formation of ATP.
B) reduction of NAD⁺.
C) creation of a proton gradient.
D) restoration of the Na⁺-K⁺ balance across the membrane.
E) reduction of glucose to lactic acid.

Question 22

During the energy-investing portion of glycolysis,the phosphates from ATP molecules are

A) added to the first and sixth carbons of glucose.
B) added to the second and fourth carbons of glucose.
C) wasted,as an energy investment in glucose.
D) used to make pyruvate from glucose.
E) used to make lactate from glucose.

Question 23

Which statement about the electron transport chain is true?

A) Electrons are received from NADH and FADH₂.
B) Electrons are passed from donor to recipient carrier molecules in a series of oxidation-reduction reactions.
C) The terminal electron acceptor is usually oxygen.
D) Most of the enzymes are part of the inner mitochondrial membrane.
E) All of the above

Question 24

In the conversion of succinate to fumarate,hydrogen atoms are transferred to FAD.The conversion of succinate and FAD to fumarate and FADH₂ is an example of

A) hydrolysis.
B) an allosteric reaction.
C) a metabolic pathway.
D) an aerobic reaction.
E) a redox reaction.

Question 25

The oxidizing agent at the end of the electron transport chain is

A) O₂.
B) NAD⁺.
C) ATP.
D) FAD.
E) ubiquinone.

Question 26

Pyruvate oxidation generates

A) acetate.
B) NADH.
C) a change in free energy.
D) CO₂.
E) All of the above

Question 27

The citric acid cycle begins with

A) glucose.
B) pyruvate.
C) acetyl CoA.
D) NADH + H⁺.
E) ATP synthase.

Question 28

Which of the following is produced during the citric acid cycle?

A) FAD
B) Pyruvate
C) Reduced electron carriers
D) Lactic acid
E) Water

Question 29

During the first step of the citric acid cycle,energy stored in acetyl CoA is used to

A) create a proton gradient.
B) drive the reaction ADP + P_i $\rightarrow$ ATP.
C) reduce NAD⁺ to NADH.
D) drive the reaction oxaloacetate $\rightarrow$ citric acid.
E) reduce FAD to FADH₂.

Question 30

The electron transport chain contains four large protein complexes.These proteins

A) are embedded in the inner membrane of the mitochondrion.
B) change in a similar way when reduced.
C) regulate the passage of water through the respiratory chain.
D) reduce NADH.
E) complete the oxidation of pyruvate to acetate.

Question 31

The citric acid cycle

A) has no connection with the respiratory chain.
B) takes place in the mitochondrion.
C) reduces two NAD⁺ for every glucose processed.
D) produces no ATP.
E) is the same thing as fermentation.

Question 32

For the citric acid cycle to proceed,it is necessary for

A) pyruvate to bind to oxaloacetate.
B) carbon dioxide to bind to oxaloacetate.
C) an acetyl group to bind to oxaloacetate.
D) water to be oxidized.
E) acetyl CoA to be reduced.

Question 33

More free energy is released during the citric acid cycle than during glycolysis,but only 1 mole of ATP is produced for each mole of acetyl CoA that enters the cycle.Most of the remaining free energy produced during the citric acid cycle is

A) used to synthesize GTP.
B) used to reduce electron carriers.
C) lost as heat.
D) used to reduce pyruvate.
E) converted to kinetic energy.

Question 34

Animals inhale air containing oxygen and exhale air with less oxygen and more carbon dioxide.Most of the carbon dioxide comes from

A) hydrocarbons and the air.
B) the citric acid cycle.
C) glycolysis.
D) waste products.
E) pyruvate oxidation.

Question 35

The chemiosmotic generation of ATP is driven by

A) osmotic movement of water into an area of high solute concentration.
B) the addition of protons to ADP and phosphate via enzymes.
C) oxidative phosphorylation.
D) the proton motive force.
E) isocitrate dehydrogenase.

Question 36

The oxidation of malate to oxaloacetate is coupled to the reduction of the coenzyme NAD⁺ to NADH + H⁺.NAD⁺ is a(n)

A) reducing agent.
B) oxidizing agent.
C) vitamin.
D) phosphate ester.
E) phosphorylating agent.

Question 37

In the conversion of pyruvate to acetyl CoA,hydrogen atoms are transferred to NAD⁺.The conversion of pyruvate to acetyl CoA is an example of

A) hydrolysis.
B) an allosteric reaction.
C) a metabolic pathway.
D) a reduction reaction.
E) a redox reaction.

Question 38

The respiratory chain

A) is located in the mitochondrial matrix.
B) includes only peripheral membrane proteins.
C) always produces ATP.
D) reoxidizes reduced coenzymes.
E) operates simultaneously with fermentation.

Question 39

In the cell,the site of oxygen utilization is the

A) nucleus.
B) chloroplast.
C) endoplasmic reticulum.
D) mitochondrion.
E) cytosol.

Question 40

In the citric acid cycle,oxidative steps are coupled to

A) oxidative phosphorylation.
B) the oxidation of water.
C) the oxidation of electron carriers.
D) the hydrolysis of ATP.
E) the reduction of electron carriers.

Question 41

Compared with fermentation,the aerobic pathways of glucose metabolism produce

A) more ATP.
B) pyruvate.
C) fewer protons for pumping in the mitochondria.
D) less CO₂.
E) more oxidized coenzymes.

Question 42

The four large protein complexes in the electron transport chain

A) transport electrons.
B) ensure the production of water and oxygen.
C) regulate the passage of water through the chain.
D) reduce NAD⁺.
E) can also serve as sodium ion channels.

Question 43

Most ATP produced in our bodies is made

A) by glycolysis.
B) in the citric acid cycle.
C) using ATP synthase.
D) from photosynthesis.
E) by burning fat.

Question 44

Which event occurs as part of the electron transport chain?

A) Release of CO₂
B) Reduction of CO₂
C) Oxidation of FADH and NADH
D) Reduction of NAD⁺
E) Formation of GTP

Question 45

According to the chemiosmotic theory,the energy for the synthesis of ATP as electrons flow down the respiratory chain is provided directly by the

A) hydrolysis of GTP.
B) reduction of NAD⁺.
C) diffusion of protons.
D) reduction of FAD.
E) hydrolysis of ATP.

Question 46

Overall,four molecules of ATP are produced by glycolysis.However,the products of glycolysis are two ATP molecules,two pyruvate molecules,and two NADH molecules.The ATP values do not match because

A) glucose metabolism is inefficient.
B) glucose phosphate is formed from fructose phosphate.
C) glucose is degraded to CO₂.
D) two ATP are invested in the process of glycolysis.
E) two phosphates are transferred to GDP.

Question 47

The hydrogen ion gradient is maintained by

A) electron transport and proton pumping.
B) the splitting of water.
C) the ionization of glucose.
D) ATP synthase.
E) acetyl CoA.

Question 48

The component of aerobic respiration that produces the most ATP per mole of glucose is

A) the electron transport chain.
B) the citric acid cycle.
C) glycolysis.
D) lactic acid fermentation.
E) alcoholic fermentation.

Question 49

During the fermentation of one molecule of glucose,the net production of ATP is _______ molecule(s).

A) one
B) two
C) three
D) six
E) eight

Question 50

Fermentation

A) takes place in the mitochondrion.
B) takes place in all animal cells.
C) does not require O₂.
D) requires lactic acid.
E) prevents glycolysis.

Question 51

The drug 2,4-dinitrophenol (DNP)destroys the proton gradient across the inner mitochondrial membrane.What would be the effect of incubating isolated mitochondria in a solution of DNP?

A) Oxygen would no longer be reduced to water.
B) No ATP would be made.
C) Mitochondria would show a burst of increased ATP synthesis.
D) Glycolysis would stop.
E) Mitochondria would switch from glycolysis to fermentation.

Question 52

The formation of ethanol from pyruvate is an example of

A) an exergonic reaction.
B) an extra source of energy as the result of glycolysis.
C) a fermentation process that takes place in the absence of oxygen.
D) cellular respiration.
E) chemiosmosis.

Question 53

Many species derive their energy from fermentation,which

A) reduces NAD⁺.
B) oxidizes CO₂.
C) ensures a continued supply of ATP.
D) produces acetyl CoA.
E) catabolizes carbohydrates.

Question 54

If a cell is labeled with ¹⁸O (an isotope of O₂),most of the isotope will be detected in the _______ of the cell.

A) nucleus
B) chloroplast
C) endoplasmic reticulum
D) mitochondrion
E) cytosol

Question 55

Which process occurs when oxygen is not available?

A) Pyruvate oxidation
B) The citric acid cycle
C) Fermentation
D) An electron transport chain
E) Chemiosmosis

Question 56

How does the reduction of pyruvate to lactic acid during fermentation allow glycolysis to continue in the absence of oxygen?

A) Water is formed during this reaction.
B) This reaction is a kinase reaction.
C) This reaction is coupled to the oxidation of NADH to NAD⁺.
D) This reaction is coupled to the formation of ATP.
E) This reaction is coupled to the reduction of NAD⁺ to NADH.

Question 57

Regardless of the electron or hydrogen acceptor employed,fermentation always produces

A) AMP.
B) DNA.
C) P_i.
D) NAD⁺.
E) GTP.

Question 58

In alcoholic fermentation,NAD⁺ is produced during the

A) oxidation of pyruvate to acetyl CoA.
B) reduction of pyruvate to lactic acid.
C) reduction of acetaldehyde to ethanol.
D) hydrolysis of ATP to ADP.
E) oxidation of glucose.

Question 59

The water that is a by-product of cellular respiration is produced as a result of the

A) combining of carbon dioxide with protons.
B) conversion of pyruvate to acetyl CoA.
C) degradation of glucose to pyruvate.
D) reduction of oxygen at the end of the electron transport chain.
E) oxidation of acetyl CoA.

Question 60

The first and third reactions of the glycolytic pathway result in consumption of ATP.This is an example of a(n)

A) endergonic reaction.
B) allosteric reaction.
C) metabolic pathway.
D) oxidation reaction.
E) exergonic reaction.

Question 61

In human muscle cells,the fermentation process produces

A) lactic acid.
B) 12 moles of ATP.
C) pyruvic acid.
D) more energy than is needed by the muscles to perform their functions.
E) ethanol.

Question 62

Compared to long-wavelength photons,short-wavelength photons have

A) an insignificant amount of energy.
B) more energy.
C) energy not available to plant cells.
D) a ladder of energy.
E) an equal amount of energy.

Question 63

When acetyl CoA builds up in the cell,it increases the activity of the enzyme that synthesizes oxaloacetate from pyruvate and CO₂.In this case,acetyl CoA is acting as a(n)

A) electron carrier.
B) substrate.
C) allosteric activator.
D) acetate donor.
E) proton pump.

Question 64

A molecule that has an absorption spectrum showing maximum absorption within the wavelengths of visible light is

A) a reducing agent.
B) a quantum.
C) a photon.
D) electromagnetic radiation.
E) a pigment.

Question 65

The first pathway of photosynthesis,in which light energy is converted into chemical energy in the form of ATP and NADPH,is referred to as the

A) light reductions.
B) dark reactions.
C) carbon-fixation reactions.
D) light reactions.
E) dark reductions.

Question 66

In the absence of oxygen,cells capable of fermentation

A) accumulate glucose.
B) no longer produce ATP.
C) accumulate pyruvate.
D) oxidize FAD.
E) oxidize NADH to produce NAD⁺.

Question 67

When bacteria are shifted from an aerobic to an anaerobic environment,they can continue to grow relatively rapidly by

A) increasing the rate of the citric acid cycle.
B) producing more ATP per mole of glucose during glycolysis.
C) producing ATP during the oxidation of NADH.
D) increasing the rate of electron transport down the respiratory chain.
E) increasing the rate of the glycolytic reactions.

Question 68

A person on a dangerously severe diet will eventually suffer from malnutrition and even starvation.If a person does not eat enough to fuel sufficient ATP and NADH production for biological activities,energy sources will be depleted.Which of the following represents the correct order in which this depletion takes place?

A) Glycogen $\rightarrow$ fats $\rightarrow$ proteins
B) Fats $\rightarrow$ glycogen $\rightarrow$ proteins
C) Glycogen $\rightarrow$ proteins $\rightarrow$ fats
D) Fats $\rightarrow$ proteins $\rightarrow$ glycogen
E) Proteins $\rightarrow$ glycogen $\rightarrow$ fats

Question 69

Before starch can be used for respiratory ATP production,it must be hydrolyzed to

A) pyruvate.
B) fatty acids.
C) amino acids.
D) glucose.
E) oxaloacetate.

Question 70

If a cell has an abundant supply of ATP,acetyl CoA may be used

A) to enhance fermentation.
B) to enhance oxidative metabolism.
C) for fatty acid synthesis.
D) to convert glucose to glycogen.
E) in the electron transport chain.

Question 71

When the supply of acetyl CoA being produced exceeds the demands of the citric acid cycle,some of the acetyl CoA is diverted to the synthesis of

A) pyruvate.
B) NAD.
C) proteins.
D) fatty acids.
E) lactic acid.

Question 72

The wavelength of X rays is shorter than the wavelength of infrared rays.Which of the following is true?

A) X rays have more energy per unit than infrared rays have.
B) X rays have a smaller value for Planck's constant than infrared waves have.
C) X rays have a different absorption spectrum than infrared waves have.
D) X rays and infrared waves have the same frequency.
E) Infrared waves are in the ground state,whereas X rays are in the excited state.

Question 73

Which of the following is the balanced equation for the generation of sugar from sunlight,water,and CO₂?

A) 6 CO₂ + 6 H₂O $\rightarrow$ C₆H₁₂O₆ + O₂
B) 6 CO₂ + 12 H₂O $\rightarrow$ C₆H₁₂O₆ + 6 O₂ + 6 H₂O
C) 6 CO₂ + 6 H₂O $\rightarrow$ C₆H₁₂O₆ + 6 O₂
D) 12 CO₂ + 12 H₂O $\rightarrow$ 2 C₆H₁₂O₆ + 2 O₂
E) None of the above

Question 74

Yeast cells tend to create anaerobic conditions and therefore

A) exhibit a red pigment.
B) exhibit a green pigment.
C) die.
D) produce ethanol.
E) None of the above

Question 75

When a photon interacts with molecules such as those within chloroplasts,the photons may

A) bounce off the molecules,having no effect.
B) pass through the molecules,having no effect.
C) be absorbed by the molecules.
D) be scattered.
E) All of the above

Question 76

When a suspension of algae is incubated in a flask in the presence of light and CO₂ and then transferred to the dark,the reduction of 3-phosphoglycerate to glyceraldehyde 3-phosphate is blocked.This reaction stops in the dark because

A) the reaction requires CO₂.
B) the reaction is exergonic.
C) the reaction requires ATP and NADPH.
D) the reaction requires O₂.
E) chlorophyll is not synthesized in the dark.

Question 77

Which biological group is dependent on photosynthesis for its survival?

A) Vertebrates
B) Mammals
C) Fishes
D) Plants
E) All of the above

Question 78

How do red and blue light differ from each other?

A) They differ in intensity.
B) They have a different number of photons in each quantum.
C) Their wavelengths are different.
D) They differ in duration.
E) Red is radiant,whereas blue is electromagnetic.

Question 79

Which pathway requires the greatest input of energy to make its product?

A) Noncyclic electron transport
B) Carbon fixation
C) Calvin cycle
D) Cyclic electron transport
E) Photophosphorylation

Question 80

Which of the following occurs during the carbon-fixation reactions of photosynthesis?

A) Water is converted into hydrogen and water.
B) CO₂ and water are converted into sugars.
C) Chlorophyll acts as an enzyme.
D) Nothing occurs;the plant rests in the dark.
E) Glucose and oxygen are reduced to CO₂ and water.