Deck 6: Energy, Enzymes, and Cellular Respiration

Question 1

In ALL exergonic reactions,

A)the products have more total energy than the reactants.
B)the reactions are nonspontaneous.
C)the reaction proceeds with a net release of free energy.
D)a net input of energy from the surroundings is required for the reactions to proceeD.
E)some reactants will be converted to products.

Answer 1

C

Question 2

All of the following are a form of potential energy that can be used by a cell EXCEPT

A)nitrogen.
B)NADH.
C)an electrical/ion gradient.
D)ATP.
E)concentration gradient.

Answer 2

A

Question 3

The charge on amino acids in the active site of an enzyme would be affected by

A)substrate concentration.
B)antibiotics.
C)salt concentration.
D)temperature.
E)pH.

Answer 3

E

Question 4

What would you predict about a reaction that has a ?G $<$
0?

A)The reaction will require energy and is spontaneous.
B)The reaction will require energy.
C)The reaction will yield energy.
D)The reaction is spontaneous.
E)The reaction will yield energy and is spontaneous.

Question 5

Which reaction would require being coupled to the hydrolysis of at least two ATP molecules ( $\Delta$ G = -14.6 kCal)in order to occur?

A) $\Delta$ G = -14.6 kCal
B) $\Delta$ G = -8 kCal
C) $\Delta$ G = +8 kCal
D) $\Delta$ G = +16 kCal
E) $\Delta$ G = -16 kCal

Question 6

If one were to double the amount of enzyme in a reaction with an initial $\Delta$ G of -5 kcal/mole,what would the $\Delta$ G be?

A)+5 kcal/mole
B)-5 kcal/mole
C)-20 kcal/mole
D)-10 kcal/mole
E)+10 kcal/mole

Question 7

In photosynthesis,carbon dioxide gas is reduced and combined to form glucose.This is an example of

A)metabolism.
B)hydrolysis.
C)catabolism.
D)exergonic.
E)anabolism.

Question 8

How can a living cell increase the rate of a chemical reaction?

A)By raising the pH of the cytoplasm.
B)By increasing the entropy of the reactants.
C)By lowering the pH of the cytoplasm.
D)By raising the temperature.
E)By using a catalyst.

Question 9

What would your predict about the reaction: $$P i + A D P \rightarrow A T P$$
?

A)It can be used to drive endergonic reactions.
B)It yields energy.
C)It has a change in free energy that is greater than 0,and hence can be used to drive endergonic reactions.
D)It has a change in free energy that is greater than 0.
E)It has a change in free energy that is less than 0.

Question 10

A bowl of sugar water is very stable.But if you feed it to cells it is rapidly broken down into carbon dioxide and water.What is the best explanation for this observation?

A)Glucose is removed from the cell by active transport.
B)Cells use energy to break down glucose.
C)Glucose cannot be broken down outside a cell.
D)Glucose becomes more chemically reactive inside a cell.
E)Enzymes in the cell catalyze the breakdown of glucosE.

Question 11

A chemical reaction that has a positive $\Delta$ G is correctly described as

A)spontaneous
B)endergonic.
C)exothermiC.
D)enthalpic.
E)endothermic.

Question 12

A logical consequence of the second law of thermodynamics could be stated,

A)every chemical reaction must increase the total entropy of the universe.
B)if the entropy of a system increases,there must be a corresponding decrease in the entropy of the universe.
C)every energy transfer requires activation energy from the environment.
D)if there is an increase in the energy of a system,there must be a corresponding decrease in the energy of the rest of the universe.
E)energy can be transferred or transformed,but it cannot be created or destroyed.

Question 13

The amount of available energy that can be used to do work is called

A)kinetic energy.
B)entropy.
C)enthalpy.
D)free energy.
E)heat.

Question 14

The primary function of an enzyme or any biological catalyst is to

A)increase the rate of a reaction.
B)reduce the energy of activation of a reaction.
C)increase the rate of a reaction and change the direction of a reaction.
D)change the direction of a reaction.
E)reduce the energy of activation and increase the rate of a reaction.

Question 15

In a catabolic reaction,electrons from food are

A)removed by reduction and stored in NADH.
B)added by reduction and stored in ATP.
C)added by oxidation and stored in ATP.
D)added by reduction and stored in NADH.
E)removed by oxidation and stored in NADH.

Question 16

How does an enzyme work to catalyze a reaction?

A)It raises the temperature of a reaction.
B)It increases the concentration of the reactants in a reaction.
C)It supplies the energy to speed up a reaction.
D)It lowers the activation energy of a reaction.
E)It allows the reaction to proceed through different intermediates.

Question 17

Water held behind a dam would best reflect

A)chemical energy.
B)mechanical energy.
C)heat energy.
D)kinetic energy.
E)potential energy.

Question 18

The reaction phosphoenolpyruvate + ADP $\rarr$ pyruvate + ATP ( $\Delta$ G = -7.5 kcal/mole),

A)consumes energy.
B)is not spontaneous.
C)is an endergonic reaction.
D)requires that energy is being transferred from phosphoenolpyruvate to ADP.
E)requires that energy is being transferred from ADP to phosphoenolpyruvatE.

Question 19

Once ATP donates its phosphate to a coupled reaction it becomes ADP.The ADP can be converted back to ATP in a(an)

A)endergonic reaction.
B)exergonic reaction.
C)oxidation reaction.
D)hydrolysis reaction.
E)equilibrium reaction.

Question 20

Altering the three-dimensional structure of an enzyme might

A)prevent the substrate from binding the enzyme's active site.
B)change the type of substrate that binds the enzyme's active site.
C)change the amount of energy needed for a reaction.
D)change the type of product produced in the reaction.
E)prevent the enzyme from adding energy to a reaction.

Question 21

For a reaction to be spontaneous it must show a net decrease in both energy and entropy.

Question 22

In the equation,C₆H₁₂O₆ + 6O₂ $\rarr$ 6CO₂ + 6H₂O,ATP and heat would be on which side of the reaction?

A)The reactants because this is an endergonic reaction.
B)The reactants because this is an exergonic reaction.
C)The products because this is an endergonic reaction.
D)It could appear on either size because this reaction is in equilibrium.
E)The products because this is an exergonic reaction.

Question 23

How many ATP and NADH molecules are produced from each molecule of glucose in the citric acid cycle only?

A)1 ATP,2 NADH
B)2 ATP,6 NADH
C)3 ATP,4 NADH
D)0 ATP,6 NADH
E)4 ATP,2 NADH

Question 24

You measure the amount of enzyme activity in the presence of compound X and note that as you add more substrate the amount of enzyme activity increases.This indicates that the compound X is a

A)competitive inhibitor.
B)allosteric inhibitor.
C)activator.
D)enzyme.
E)non-competitive inhibitor.

Question 25

Where does glycolysis takes place?

A)mitochondrial matrix
B)mitochondrial intermembrane space
C)mitochondrial inner membrane
D)mitochondrial membrane
E)cytosol

Question 26

Your liver produces 90% of the cholesterol found in your body.When cholesterol levels get too high,the first enzyme in the pathway of cholesterol synthesis is inhibited.This is an example of

A)negative feedback.
B)positive feedback.
C)denaturation.
D)a coenzyme.
E)equilibrium.

Question 27

The process of breaking glycogen down to glucose is an example of

A)catabolism
B)catalysis
C)dehydration
D)anabolism
E)metabolism

Question 28

Catabolic and anabolic reactions in living cells involve the transfer of electrons from one molecule to another in reduction-oxidation reactions.

Question 29

The equation,C₆H₁₂O₆ + 6O₂ $\rarr$ 6CO₂ + 6H₂O (ATP + Heat),describes what process?

A)photosynthesis
B)anaerobic metabolism
C)glycolysis
D)cell fermentation
E)cell respiration

Question 30

Noncompetitive inhibitors bind the active site of an enzyme,reducing its activity and the subsequent formation of product.

Question 31

In the reaction A^- +B $\rarr$ A + B^-,

A)molecule A is oxidized and molecule B is reduced.
B)molecules A and B are both reduced.
C)molecule A is reduced and molecule B is oxidized.
D)molecule A is oxidized and molecule B is unchangeD.
E)molecules A and B are both oxidzied.

Question 32

What are the final by-products of glucose oxidation during aerobic cell respiration?

A)ATP,heat,and carbon dioxide
B)both ATP and heat only
C)carbon dioxide only
D)heat only
E)ATP only

Question 33

Enzymes are consumed in chemical reactions and must therefore be replenished.

Question 34

How many net ATP and NADH molecules are produced from one molecule of glucose during glycolysis?

A)3 ATP,4 NADH
B)4 ATP,2 NADH
C)2 ATP,2 NADH
D)2 ATP,6 NADH
E)0 ATP,6 NADH

Question 35

Metabolism refers to only those reactions that release energy.

Question 36

Cellular respiration produces the most energy in the form of ATP from

A)the production of lactate
B)glycolysis
C)substrate-level phosphorylation
D)oxidative phosphorylation
E)the citric acid cycle

Question 37

What processes will occur in the presence or absence of oxygen?

A)glycolysis
B)electron transport chain
C)cellular respiration
D)oxidative phosphorylation
E)citric acid cycle

Question 38

Temperature,pH,and ionic concentrations each play an important role in the proper functioning of enzymes.

Question 39

What is produced during the citric acid cycle?

A)Pyruvate,ATP and NADH.
B)ATP and NAD⁺.
C)ATP,NADH,and FADH₂.
D)Oxygen.
E)A proton gradient.

Question 40

A reaction with a ? $>$
0 is endergonic and requires a net input of energy to procede.

Question 41

Oxygen is an excellent final electron acceptor because of its low electronegativity.

Question 42

The enzyme responsible for converting pyruvate to acetyl CoA is called

A)hexokinase.
B)pyruvate oxidase.
C)ATP synthase.
D)pyruvate dehydrogenase.
E)peptidasE.

Question 43

High-energy electrons from molecules of NADH and FADH₂ are transferred to a chain of proteins within the electron transport chain.What is the final protein in the electron transport chain?

A)carbon dioxide
B)NAD⁺
C)ubiquinone
D)cytochrome c
E)oxygen

Question 44

Which would be TRUE if an inhibitor blocked the activity of mitochondrial ATP synthase?

A)The pH in the space between the mitochondrial membranes would decrease.
B)The pH in the space between the mitochondrial membranes would increase.
C)Oxygen consumption would decrease.
D)ATP synthesis would increase.
E)The concentration of NADH would increasE.

Question 45

Glycolysis involves 10 enzyme-catalyzed steps,that can be grouped into three phases: energy investment phase,cleavage phase,and the energy liberation phase.

Question 46

In the citric acid cycle,malate is oxidized to form

A)succinate.
B)fumarate.
C)malate.
D)oxaloacetate.
E)citratE.

Question 47

During the cleavage stage of glycolysis,fructose-1,6 biphosphate is broken down into

A)citric acid.
B)two molecules of ATP.
C)two molecules of pyruvate.
D)two molecules of glyceraldehyde-3-phosphate.
E)glucosE.

Question 48

In the citric acid cycle,the acetyl group is removed from acetyl CoA and attached to oxaloacetate to form

A)oxaloacetate.
B)citrate.
C)malate.
D)succinate.
E)fumaratE.

Question 49

If oxygen is present,pyruvate will be converted to acetyl CoA in the mitochondrial matrix.

Question 50

Energy released by the electron transport chain is used to pump H⁺ ions into which location?

A)mitochondrial matrix
B)mitochondrial outer membrane
C)cytosol
D)mitochondrial inner membrane
E)mitochondrial intermembrane space

Question 51

Where are the protein complexes associated with the electron transport chain located?

A)mitochondrial matrix
B)mitochondrial membrane
C)mitochondrial inner membrane
D)mitochondrial intermembrane space
E)cytosol

Question 52

Which of the following statements about the electron transport chain in cell respiration is CORRECT?

A)The electron transport chain of proteins uses ATP to pump H⁺ across the inner mitochondria membrane against its electrochemical gradient.
B)The electron transport chain of proteins contains pores that are leaky to H⁺.
C)The loss in free energy of the electron initially donated by NADH is used to transport H⁺ across the inner mitochondrial membrane against its electrochemical gradient.
D)Electrons move from NADH to a chain of proteins with lower electronegativities.
E)The ATP synthase generates a H⁺ gradient across the inner mitochondrial membranE.

Question 53

The ATP made during glycolysis is generated by

A)substrate-level phosphorylation.
B)chemiosmosis.
C)photophosphorylation.
D)electron transport.
E)oxidation of NADH to NAD⁺.

Question 54

The proton motive force requires that the H⁺ concentration is lower in the intermembrane space than inside the matrix.

Question 55

Substrate phosphorylation occurs when protons pass through ATP synthase and combine with oxygen to make water.

Question 56

In addition to ATP,what are the end products of glycolysis?

A)CO₂ and NADH
B)CO₂ and pyruvate
C)H₂O,NADH,and citrate
D)NADH and pyruvate
E)CO₂ and H₂O

Question 57

Assuming that the glycerol backbone of a fat molecule can be converted to glyceraldehyde-3-phosphate,an intermediate in glycolysis,how many ATP can be produced from the glycerol backbone of a fat molecule?

A)8
B)2
C)12
D)36
E)18

Question 58

During glycolysis,glucose is broken down into

A)pyruvate.
B)ATP.
C)oxygen.
D)acetyl CoA.
E)NADH.

Question 59

In prokaryotic cells,the electron transport system occurs in the mitochondria.

Question 60

The electron transport chain consists of a series of redox reactions in which electrons are transferred to oxygen as the final electron acceptor.

Question 61

When acetyl-CoA containing radioactively labeled carbon atoms is fed to cells,the CO₂ produced is not initially radioactive.However,molecules of citrate and oxaloacetate are radioactive.Only after some time has passed will radioactive CO₂ released.What is the best explanation for this observation?

A)Acetyl groups are not metabolized directly into CO₂,but enter a linear metabolic pathway.
B)Acetyl groups are not metabolized directly into CO₂,but enter a cyclical metabolic pathway.
C)Acetyl groups first combine with citrate and oxaloacetate before being metabolized into CO₂.
D)Acetyl groups are metabolized directly into CO₂.

Question 62

In the reaction pyruvate + CoA + NAD⁺ $\rarr$ acetyl CoA + CO₂ + NADH

A)pyruvate is oxidized and CoA is reduced.
B)pyruvate is oxidized and NAD⁺ is reduced.
C)pyruvate is reduced and CoA is oxidized.
D)pyruvate is reduced and NAD⁺ is oxidizeD.

Question 63

When a molecule of NAD⁺ gains a hydrogen atom,the molecule becomes reduced.

Question 64

The reaction: pyruvate + CoA + NAD⁺ $\rarr$ acetyl CoA + CO₂ + NADH,is catalyzed by pyruvate dehydrogenase.If an inhibitor of this enzyme was added to cells levels of which compound would increase in the cytoplasm?

A)NAD⁺
B)Pyruvate
C)Acetyl CoA
D)CoA

Question 65

When scientists placed ATP Synthase linked to fluorsecent actin on a microscope slide and added ATP,the actin could be seen spinning counterclockwise.If the experiment could be replicated in a cell going through oxidative phosphorylation what would happen?

A)The actin would spin counterclockwise because ATP would be hydrolyzed.
B)The actin would spin clockwise because ATP would be produced instead of hydrolyzed.
C)The actin would spin counterclockwise because ATP would be produced instead of hydrolyzed.
D)The actin would spin clockwise because ATP would be hydrolyzeD.

Question 66

When scientists placed ATP Synthase linked to fluorescent actin on a microscope slide and added ATP,the actin could be seen spinning.If the scientists instead added ADP what would happen?

A)The actin would not spin because only ATP can move through the channel in ATP synthase.
B)The actin would spin when ADP is phosphorylated to form ATP.
C)The actin would not spin because it required ATP hydrolysis.
D)The actin would spin because ADP can also move through the channel in ATP synthase.

Question 67

Some bacteria can use sulfur instead of oxygen as a final electron acceptor.What would they produce during anaerobic respiration?

A)S₂
B)H₂O
C)O₂
D)H₂S

Question 68

During the energy investment phase of glycolysis,glucose has a decrease in free energy.

Question 69

In the citric acid cycle,some intermediates are used in other metabolic reactions.Which of the following adaptations would need to be made by a cell in response to this?

A)Cells would have to use energy sources other than glucose for metabolism.
B)Some oxaloacetate would need to be produced through an alternative pathway to combine with acetyl CoA.
C)Some citrate would need to be produced through an alternative pathway to combine with acetyl CoA.
D)The citric acid cycle would eventually shut down when it ran out of intermediates and the cell would switch to glycolysis.

Question 70

The conversion of pyruvate to acetyl CoA is irreversible.Predict what would happen to fatty acids as a result of this.

A)Fatty acids cannot be converted into carbohydrates.
B)Fatty acids cannot be metabolized in the citric acid cycle.
C)Fatty acids can be metabolized in glycolysis.
D)Fatty acids can be converted into carbohydrates.

Question 71

The formation of each pyruvate in glycolysis also produces a net of 2 NADH and 2 ATP.However,each metabolism of glucose produces a net of 4 NADH and 4 ATP.How is this explained?

A)Glucose is cleaved into two three carbon sugars that are metabolized into pyruvate.
B)Pyruvate can also be fermented,which decreases the energy produced.
C)Glucose is metabolized by a different,more efficient pathway than pyruvate.
D)Energy is added to glucose which increases the amount of ATP produced per glucose molecule.

Question 72

In a PET scan a patient is injected with radioactively labeled glucose.Why would cancer cells take up more of the radioactive glucose than surrounding non-cancerous tissues?

A)Because the produce more enzymes found in glycolysis.
B)Because they are more sensitive to radiation.
C)Because they require more oxygen to metabolize glucose.
D)Because they rely more on oxidative phosphorylation than glycolysis to produce ATP.
E)Because they are less sensitive to radiation.

Question 73

Bacteria that produce nitrite ( NO₂^- )during anaerobic respiration would use this as their final electron acceptor.

A)N₂
B)O₂
C)N₂O
D)NO₃^-

Question 74

In a PET scan a patient is injected with radioactively labeled glucose.Cancer cells are often in a hypoxic environment,why would this lead to an increase in glucose uptake?

A)More energy is produced from glucose in hypoxic conditions.
B)They rely more on glycolysis which is less efficient than oxidative phosphorylation.
C)They rely more on oxidative phosphorylation which is less efficient than glycolysis.
D)Enzymes function more efficiently in the absence of oxygen.
E)Because they require more oxygen to metabolize glucosE.