Deck 7: How Cells Harvest Energy

Question 1

A molecule that stores energy by linking charged phosphate groups near each other is called

A)ATP.
B)NADH.
C)FADH.
D)cyclic AMP.
E)pyruvatE.

Answer 1

A

Question 2

At least 90% of organisms on the earth are heterotrophs.Examples include all of the following except

A)plants.
B)fungi.
C)most eubacteria.
D)animals.
E)most protests.

Answer 2

A

Question 3

All of the reactions of glucose oxidation that follow glycolysis,and involve the transfer of electrons to their final acceptor,take place in eukaryotic cells in the ___________.

A)chloroplasts
B)nucleus
C)mitochondria
D)plasma membrane

Answer 3

C

Question 4

The return of the protons into the mitochondrial matrix through mitochondrial membrane channels occurs by the process of _________.

A)diffusion
B)osmosis
C)active transport
D)reversal of potential

Question 5

The first stage of cellular respiration,_____________,occurs with or without oxygen present.

A)the Kreb's cycle
B)glycolysis
C)gluconeogenesis
D)cleavage

Question 6

An electron carrier that is used in harvesting energy from glucose molecules in a series of gradual steps in the cytoplasm is

A)pyruvate.
B)cyclic AMP.
C)ATP.
D)NAD⁺.
E)NADH.

Question 7

In eukaryotes,the glycolytic reactions take place in the

A)mitochondria of the cell.
B)cytoplasm of the cell.
C)ribosomes of the cell.
D)endoplasmic reticulum of each cell.
E)Golgi bodies of the cell.

Question 8

The amino acids must be first __________ before they can be used in catabolic reactions.

A)stripped
B)proteins
C)deoxygenated
D)deaminated

Question 9

When oxygen is limiting,during heavy exercise,muscle cells revert to ________________ fermentation for energy production.

A)alcohol
B)yeast
C)aerobic
D)lactic acid

Question 10

For further derivation of energy,aerobic cells must convert pyruvate into acetyl-CoA by stripping off a C0₂ molecule.This process is known as ___________.

A)decarboxylation
B)glycolysis
C)The Kreb's cycle
D)metabolism

Question 11

The first stage of cellular respiration,and the oldest in terms of evolution is

A)decarboxylation.
B)deamination.
C)fermentation.
D)chemiosmosis.
E)glycolysis.

Question 12

In the absence of oxygen,hydrogen atoms generated by glycolysis are donated to organic molecules in a process called

A)fermentation.
B)decarboxylation.
C)chemiosmosis.
D)electron transport chain reactions.
E)acetyl-CoA formation.

Question 13

Simple molecules are further broken down in cells in a process called _________,during which energy stored in their chemical bonds is used to power the production of ATP.

A)photosynthesis
B)anabolism
C)respiration
D)muscle contraction

Question 14

Organisms that can manufacture their own chemical energy sources are called _____________.

A)autotrophs
B)heterotrophs
C)oligotrophs
D)chemotrophs

Question 15

Because the chemical formation of ATP is driven by a diffusion force similar to osmosis,this process is referred to as ___________.

A)active transport
B)chemiosmosis
C)decarboxylation
D)diffusion

Question 16

Which of the following statements about fermentation is false?

A)Fermentation takes place only in the absence of oxygen.
B)The recipient of hydrogen atoms is an organic molecule.
C)Water is not one of the by-products.
D)The Krebs cycle and electron transfer system do not occur.
E)Cells can only undergo one type of fermentation.

Question 17

In glycolysis,a major portion of the energy remains in the final product,which is called ________.

A)glucose
B)carbon dioxide
C)ATP
D)pyruvate

Question 18

Glucose is broken down to carbon dioxide and water in organisms which breathe air in a process called ________ respiration.

A)anaerobic
B)continuous
C)glucose
D)aerobic

Question 19

________ depend on energy stored in chemical bonds by autotrophs for their food energy.

A)autotrophs
B)heterotrophs
C)oligotrophs
D)chemotrophs

Question 20

Fats undergo a process called ________ oxidation,in which the products are acetyl coenzyme molecules.

A)alpha
B)beta
C)gamma
D)omega

Question 21

A process common to all living organisms,aerobic and anaerobic,is

A)glycolysis.
B)fermentation.
C)the Krebs cycle.
D)electron transport chain reactions.
E)pyruvate oxidation.

Question 22

The electron transport chain consists of all of the following except

A)NADH dehydrogenase.
B)cytochrome complex.
C)oxygenase.
D)cytochrome c oxidase.
E)ubiquinone Q.

Question 23

The end-product of glycolysis is

A)ATP.
B)NAD⁺.
C)alcohol.
D)ADP.
E)pyruvatE.

Question 24

The decarboxylation of pyruvate produces all of the following except

A)NADH.
B)acetyl-CoA.
C)CO₂.
D)ATP.

Question 25

The enzymes of the Krebs cycle are located in the

A)cytoplasm.
B)inter-membrane space of mitochondria.
C)vesicles of the ER.
D)outer membrane of the mitochondria.
E)matrix of the mitochondria.

Question 26

In oxidative respiration,energy is harvested from glucose molecules in a sequence of four major pathways.Which of the following is not one of these four pathways?

A)Krebs cycle
B)glycolysis
C)electron transfer through the transport chain
D)beta oxidation
E)pyruvate oxidation

Question 27

In which of the following steps of glycolysis are two ATP molecules are required?

A)cleavage and rearrangement
B)glucose priming
C)oxidation
D)pyruvate formation
E)acetyl-CoA formation

Question 28

Chemiosmotic generation of ATP is driven by

A)P_i transfer through the plasma membrane.
B)the Na⁺/K⁺ pump.
C)a difference in H⁺ concentration on the two sides of the mitochondrial membrane.
D)osmosis of macromolecules.
E)large quantities of ADP.

Question 29

The enzymes catalyzing the reactions of glycolysis are found in the

A)mitochondriA.
B)cytoplasm.
C)chloroplasts.
D)nucleus.
E)Golgi apparatus.

Question 30

All of the following are the end products of glycolysis except

A)pyruvate.
B)ATP.
C)NADH.
D)NAD⁺.
E)energy.

Question 31

The oxygen utilized in cellular respiration finally shows up as

A)CO₂.
B)ATP.
C)new O₂.
D)H₂O.
E)part of a sugar.

Question 32

The coenzyme electron carriers produced in the Krebs cycle are

A)ATP and ADP.
B)pyruvate and acetyl-CoA.
C)FADH₂ and NADH.
D)NAD and NADH.
E)NADH and ATP.

Question 33

The decarboxylation step of oxidation of pyruvate takes place in the

A)cytoplasm.
B)Golgi body.
C)ribosome.
D)mitochondrion.
E)nucleus.

Question 34

In the cyclic reaction sequence called the Krebs cycle,the following chemical events take place except

A)the acetyl group is joined with a four carbon molecule,oxaloacetate.
B)the resulting six carbon molecule is oxidized.
C)electrons generated are used to produce NADH.
D)two carbons per cycle are made into CO₂ molecules.
E)pyruvate molecules are restored to the cyclE.

Question 35

A single glucose molecule can drive the Krebs cycle

A)one turn.
B)two turns.
C)three turns.
D)four turns.
E)six turns.

Question 36

The electron transport chain,a series of membrane-associated electron carriers,loses most of the energy by driving several transmembrane

A)proton pumps.
B)electron pumps.
C)Na⁺/K⁺ pumps.
D)active transport pumps.
E)water pumps.

Question 37

The energy released in the mitochondrial electron transport chain is used to transport protons into the

A)matrix.
B)cytoplasm.
C)ER.
D)inter-membrane space of mitochondria.
E)enzyme complex of the Krebs cyclE.

Question 38

The reaction,C₆H₆O₆ + 6O₂ = 6 CO₂ + 6 H₂O,when it occurs in living cells is known as

A)aerobic fermentation.
B)anaerobic fermentation.
C)aerobic respiration.
D)glycolysis.
E)oxidative phosphorylation.

Question 39

Since membranes are relatively impermeable to ions,most of the protons re-enter the matrix by passing through special channels in the inner mitochondrial membrane.Because of the inward flow of protons these channels allow the synthesis of

A)ADP from ATP and Pi.
B)ATP from ADP and Pi.
C)glucose from pyruvate.
D)acetyl-CoA from pyruvate.
E)citrate from oxaloacetate and acetyl-CoA.

Question 40

Out of the total amount of free energy potentially available from total oxidation of glucose,the number of ATP made by cells is equal to an energy efficiency of about

A)2%.
B)25%.
C)32%.
D)75%.
E)90%.

Question 41

During aerobic respiration the final acceptor of the hydrogen atoms is

A)oxygen.
B)carbon dioxide.
C)water.
D)glucose.
E)pyruvatE.

Question 42

A biochemist wants to control the initial substrate-level phosphorylation that occurs in the tracheal cells of grasshoppers once glucose has crossed the plasma membrane.This means that he will

A)have to prevent cAMP from entering the tracheal cells.
B)have to prevent pyruvate reduction from occurring.
C)have to prevent glycolysis from occurring in the mitochondria.
D)have to prevent glycolysis from occurring in the cytoplasm.
E)have to prevent aerobic respiration in the cytoplasm.

Question 43

Coenzyme electron carrier;associated with Krebs cycle only.

A)ATP
B)FAD
C)G3P
D)NAD⁺
E)acetyl-CoA

Question 44

In muscle cells,fermentation produces not alcohol but

A)ATP.
B)NADH.
C)pyruvate.
D)kinetic energy.
E)lactic acid.

Question 45

Which of the following statements accurately reflects what happens to a glucose molecule during the initial five phases of glycolysis?

A)Glucose,a six-carbon sugar,enters the cell by passive transport and is primed and converted into glucose three-phosphate,which requires two ATP molecules.The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules.
B)Glucose,a six-carbon sugar,enters the cell by active transport and is primed and converted into glucose three-phosphate,which requires two ATP molecules.The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules.
C)Glucose,a six-carbon sugar,enters the cell by simple diffusion and is primed and converted into glucose three-phosphate,which requires two ATP molecules.The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules.
D)Glucose,a six-carbon sugar,enters the cell by G protein mediation and is primed and converted into glucose three-phosphate,which requires two ATP molecules.The remaining four steps involve splitting the six-carbon molecule into two three-carbon molecules.

Question 46

What type of cell respiration occurs when an organic molecule accepts hydrogen atoms?

A)aerobic respiration
B)anaerobic respiration
C)fermentation
D)catabolism
E)digestion

Question 47

Beta oxidation of these molecules converts them into acetyl-CoA,which can then enter the Krebs cycle for energy derivation.These are

A)fatty acids.
B)amino acids.
C)ATP.
D)nucleic acids.
E)sugars.

Question 48

Regardless of the electron or hydrogen acceptor used,one of the products of fermentation is always

A)ADP.
B)ATP.
C)NAD⁺.
D)pyruvate.
E)alcohol.

Question 49

Cytochromes are respiratory proteins.Which of the following statements accurately reflects their true nature?

A)Cytochrome proteins reside free in the lung cells of all vertebrates.These molecules contain a heme group with an iron atom at its center.
B)Cytochrome proteins reside in the mitochondria and are specifically associated with the electron transport system.
C)Cytochrome proteins reside in the mitochondria and are specifically associated with the Kreb cycle.
D)Cytochrome proteins reside in the mitochondria and are specifically associated with glycolysis.

Question 50

Intermediate in glycolysis;finally oxidized to pyruvate.

A)ATP
B)FAD
C)G3P
D)NAD⁺
E)acetyl-CoA

Question 51

Pyruvate oxidation;carrier of acetyl groups.

A)ATP
B)FAD
C)G3P
D)NAD⁺
E)acetyl-CoA

Question 52

When ATP levels are high,oxidative pathways are inhibited,so acetyl-CoA is channeled into

A)fatty acid synthesis.
B)pyruvate formation.
C)the Krebs cycle.
D)the electron transport system.
E)NAD production.

Question 53

When substrate-level phosphorylation occurs,it means that

A)NAD is converted into NADH.
B)ATP is converted into ADP + a phosphate group.
C)ADP is converted into ATP by addition of a phosphate group.
D)cAMP is converted into ADP by adding a phosphate group.
E)NADH is converted into NAD + H.

Question 54

Select the correct sequence concerning glucose catabolism.

A)glycolysis $\rarr$ Pyruvate $\rarr$ Acetyl CoA $\rarr$ Electron Transport Chain $\rarr$ Krebs Cycle
B)glycolysis $\rarr$ Pyruvate $\rarr$ Acetyl CoA $\rarr$ Krebs Cycle $\rarr$ Electron Transport Chain
C)glycolysis $\rarr$ Acetyl CoA $\rarr$ Pyruvate $\rarr$ Electron Transport Chain $\rarr$ Krebs Cycle
D)glycolysis $\rarr$ Acetyl CoA $\rarr$ Pyruvate $\rarr$ Krebs Cycle $\rarr$ Electron Transport Chain

Question 55

Yeast cells under anaerobic conditions

A)die.
B)produce ethyl alcohol (ethanol).
C)produce oxygen.
D)switch to oxidative respiration.
E)push the glycolytic pathway backward.

Question 56

Which of the following statements accurately reflects the process of glycolysis?

A)Glycolysis is most likely one of the earliest of all biochemical reactions to evolve.Glycolysis uses molecular oxygen,however it occurs in anaerobic environments.
B)Glycolysis is most likely one of the earliest of all biochemical reactions to evolve.Glycolysis uses no molecular oxygen.All reactions of glycolysis occur free in the cytoplasm.
C)Glycolysis is most likely one of the earliest of all biochemical reactions to evolve.Glycolysis uses molecular oxygen,however it occurs in aerobic environments.
D)Glycolysis is most likely one of the earliest of all biochemical reactions to evolve.Glycolysis uses molecular oxygen and occurs in the mitochondria.

Question 57

Chief energy currency of cells;formed by chemiosmosis.

A)ATP
B)FAD
C)G3P
D)NAD⁺
E)acetyl-CoA

Question 58

Cells release energy from molecules such as glucose in a process very similar to inhalation of air and exhalation of carbon dioxide by humans.This process is known as cellular

A)oxidation.
B)reduction.
C)photosynthesis.
D)radiation.
E)respiration.

Question 59

The Krebs cycle occurs in the mitochondria.There are nine biochemical reactions involved in the Krebs cycle,and they are highly ordered.Select the correct order from the following choices.(Note: These are abbreviated and do not show NAD,ADP,ATP,or FAD. )

A)acetyl-CoA joins the Kreb cycle and unites with oxaloacetate $\rarr$ forming citrate $\rarr$ which forms beta-ketoglutarate $\rarr$ which forms succinyl-CoA $\rarr$ which forms succinate $\rarr$ which forms fumarate $\rarr$ which forms malate $\rarr$ which forms oxaloacetate
B)acetyl-CoA joins the Kreb cycle and unites with oxaloacetate $\rarr$ forming citrate $\rarr$ which forms alpha-ketoglutarate $\rarr$ which forms succinyl-CoA $\rarr$ which forms succinate $\rarr$ which forms malate $\rarr$ which forms fumarate $\rarr$ which forms oxaloacetate
C)acetyl-CoA joins the Kreb cycle and unites with oxaloacetate $\rarr$ which forms alpha-ketoglutarate $\rarr$ forming citrate $\rarr$ which forms succinyl-CoA $\rarr$ which forms succinate $\rarr$ which forms fumarate $\rarr$ which forms malate $\rarr$ which forms oxaloacetate
D)acetyl-CoA joins the Kreb cycle and unites with oxaloacetate $\rarr$ forming citrate $\rarr$ which forms alpha-ketoglutarate $\rarr$ which forms succinyl-CoA $\rarr$ which forms succinate $\rarr$ which forms fumarate $\rarr$ which forms malate $\rarr$ which forms oxaloacetate

Question 60

A gram of fatty acid can yield how many more times the energy as one gram of glucose?

A)6
B)5
C)4
D)3
E)2

Question 61

In order to lose weight and reduce body fat,a friend of yours decided to eliminate all fat from their diet,while consuming unrestricted amounts of carbohydrates.Aside from being an unhealthy way to try to lose weight,why would this approach be unsuccessful at reducing body fat?

A)Excess acetyl-CoA from glycolysis will be channeled into production of body fat.
B)Excess acetyl-CoA from the Krebs cycle will be channeled into production of body fat.
C)Excess acetyl-CoA will undergo beta-oxidation to produce body fat.
D)Excess acetyl-CoA will undergo deamination to produce body fat.

Question 62

As a forensic pathologist,you have just completed an autopsy of a poisoning victim.After a thorough examination,you conclude that the victim died of cyanide poisoning.You know that cyanide binds to the cytochrome oxidase complex,and therefore list the official cause of death as suffocation due to cyanide exposure.However,a more technical explanation would be that all of the following aspects of cellular respiration were inhibited except

A)the reduction of NAD⁺ and FAD.
B)electron transport.
C)oxidative phosphorylation.
D)proton pumping.

Question 63

Cytochromes contain a heme group similar to that in hemoglobin.The iron atom (Fe)in the center of the group can be oxidized and reduced.If someone was suffering from iron deficiency anemia,which stage of cellular respiration would be most affected?

A)glycolysis
B)Krebs cycle
C)electron transport chain
D)fermentation

Question 64

Many of the antiviral drugs currently used to treat HIV/AIDS also interfere with an enzyme that helps mitochondria multiply.Treatment can therefore result in a decrease in the number of mitochondria found in certain tissues.Given this information,which of the following might you expect to see in patients treated with antiviral drugs?

A)an increase in oxidative phosphorylation
B)an increase in phosphofructokinase activity
C)an increase in NADH dehydrogenase activity
D)an increase in lactic acid levels

Question 65

Oxidized form of the most common electron carrier;needed in both glycolysis and Krebs cycle.

A)ATP
B)FAD
C)G3P
D)NAD⁺
E)acetyl-CoA

Question 66

Why are the components of the electron transport chain embedded in the inner mitochondrial membrane rather than floating freely in the cytoplasm of mitochondrial matrix?

A)to generate and maintain the protein gradient essential for ATP production
B)to separate the ATP from the ADP
C)because electrons cannot float in the matrix
D)in order to stabilize the proteins

Question 67

The chemical 2,4 dinitrophenol (DNP)is used in the manufacturing of dyes,wood preservatives,explosives,and insect control substances,and as a photographic developer.Products containing DNP are toxic because DNP uncouples oxidative phosphorylation.In a cell exposed to DNP,how many ATP molecules would be generated per molecule of glucose?

A)2
B)4
C)36
D)38

Question 68

After eating lunch on a very cold winter day,you begin the long walk across campus to your next class.During your walk you begin thinking about glucose catabolism and the high carbohydrate meal you just consumed.As the cold wind picks up,you find yourself hoping that a lot of the energy released gets converted to heat.Which of the following statements concerning catabolism of glucose are false?

A)From a chemical standpoint,glucose burning and glucose catabolism are very similar.
B)More energy is released as heat when glucose is burned rather than catabolized.
C)Cellular energy released can be as high as -720 kcal/mol glucose.
D)More total energy is released when glucose is burned rather than catabolizeD.

Question 69

High levels of citrate in the cell would result in which of the following?

A)inhibition of phosphofructokinase and the slow down of glycolysis
B)inhibition of citrate synthase and the slow down of glycolysis
C)inhibition of phosphofructokinase and the slow down of the Krebs cycle
D)inhibition of citrate synthase and the slow down of the Krebs cycle

Question 70

You are examining some live cells in a Petri dish,when you begin to imagine what you would do if suddenly one of them were to burst into flames.Of course,in order for this to happen the cell would have to

A)transfer electrons to intermediate electron carriers before transferring them to oxygen.
B)transfer electrons directly to oxygen,skipping the intermediate electron carriers.
C)transfer electrons directly to carbon dioxide,skipping the intermediate electron carriers.
D)transfer electrons to intermediate electron carriers before transferring them to carbon dioxide.

Question 71

If ATP synthase had a mutation in the F₁ complex portion of the protein,which of the following functions is most likely to be affected?

A)rotation of the rotor
B)flow of protons through the channel
C)conversion of ADP and P_i to ATP
D)insertion of the enzyme into the membrane

Question 72

Some prokaryotic organisms use nitrogen fixation to obtain organic nitrogen.Which of the following statements about nitrogen fixation is false?

A)Nitrogen fixation requires the breaking a N $\equiv$ N triple bond.
B)Nitrogen fixation evolved after anaerobic photosynthesis,but before aerobic respiration.
C)Nitrogen fixation can only occur in the presence of oxygen.
D)Nitrogen fixation evolved as a way to obtain organic nitrogen for production of proteins and nucleic acids.

Question 73

If you were an anaerobic bacterium and needed to harvest energy,which of the following would be your best option?

A)glycolysis and fermentation
B)fermentation and cellular respiration
C)Krebs cycle and fermentation
D)fermentation only

Question 74

You arrive at your second home in the mountains looking forward to a relaxing vacation.Unfortunately,when you turn on the water you smell hydrogen sulfide (H₂S)gas.After some research,you find out that the H₂S may be due to the presence of sulfur bacteria living in your pipes.Which of the following molecules would these bacteria use as an electron acceptor?

A)O₂
B)H₂0
C)SO₄
D)H₂S

Question 75

Which of the following molecules does not cross the inner membrane of the mitochondria?

A)ATP
B)acetyl-CoA
C)pyruvate
D)oxygen

Question 76

Your friend is having difficulty keeping track of the energy flow from glucose through glycolysis,the Krebs cycle and electron transport.Your best advice would be to

A)follow ATP production.
B)follow the protons.
C)follow NAD⁺ production.
D)follow the electrons.