Deck 3: Cell Metabolism

Question 1

In a reduction reaction, which of the following is most likely added to the reactants? reactions.
Reactions.

A) water
B) oxygen
C) electrons
D) neutrons
E) phosphate

Answer 1

C

Question 2

During what type of reaction are electrons removed from the reactant?

A) electrocution
B) oxidation
C) reduction
D) phosphorylation
E) None of the answers is correct.

Answer 2

B

Question 3

Start with the following chemical reaction at equilibrium: A -B. If you add product B to the system from a separate pathway, then what change in the reaction occurs?

A) Because the reaction is at equilibrium, there will be no change in rates of either the forward or reverse reaction.
B) Because the reaction is at equilibrium, the rates of both the forward and reverse reactions increase.
C) The rate of the forward reaction increases.
D) The rate of the reverse reaction increases.
E) The rate of the forward and reverse reactions both decrease.

Answer 3

D

Question 4

Which of the following statements about the law of mass action is FALSE?

A) The slope of a curve represents the rate of reaction; the greater the slope the faster the rate of reaction.
B) Equilibrium is reached when the concentration of reactant equals the concentration of product.
C) An increase in the concentration of reactants relative to products tends to push a reaction forward, and an increase in the concentration of products relative to reactants tends to push a reaction in reverse.
D) It is critical in physiological processes because concentrations of reactants and products in cells and body fluids constantly change.
E) After reaching equilibrium, more reactant is added, which causes the production of more product.

Question 5

In the chemical equation A + B "C + D, the materials on the left -hand side of the equation are known as
)
Whereas the materials on the right -hand side of the equation are know as

A) anabolic : catabolic
B) products : reactants
C) catabolic : anabolic
D) product : substrate
E) reactants : products

Question 6

The sum of the thousands of chemical reactions that occur within the body is called

A) oxidation.
B) metabolism.
C) hydrolysis.
D) phosphorylation.
E) reduction.

Question 7

Chemical reactions that involve the production of a phosphate bond are called

A) oxidation
B) phosphorylation
C) reduction
D) dephosphorylation
E) condensation

Question 8

Which of the following is TRUE of an endergonic reaction?

A) The only product of the reaction is water.
B) The reaction proceeds spontaneously.
C) The change in energy of the reaction is positive.
D) Endergonic reactions never occur.
E) The only product of the reaction is heat.

Question 9

Making or synthesizing a protein would be considered a(n) reaction and the type of reaction that carries this process out is a

A) catabolic : condensation
B) anabolic : condensation
C) anabolic : hydrolysis
D) catabolic : hydrolysis
E) metabolic : hydrolysis

Question 10

If the energy change of a reaction (OE) is positive, then

A) no energy was added to the reaction.
B) the reactants had more energy than the products.
C) energy has been released as a byproduct.
D) the products had more energy than reactants.
E) the reactants had the same energy as the products.

Question 11

Chemical reactions that involve the breaking of a phosphate bond are called

A) condensation
B) dephosphorylation
C) phosphorylation
D) reduction
E) oxidation

Question 12

The energy that is stored within an object for later use is referred to as

A) kinetic
B) kinesthetic
C) potential
D) radiant
E) thermal

Question 13

The kinetic energy of a molecule can be increased by

A) decreasing its mass.
B) increasing its temperature.
C) decreasing its temperature.
D) decreasing its velocity.
E) increasing its mass.

Question 14

When phosphate is added to ADP to form the energy -storing molecule ATP, this is known as and, since water is also produced, this reaction is also considered a

A) phosphorylation : dephosphorylation
B) dephosphorylation : condensation
C) dephosphorylation : hydrolysis
D) phosphorylation : hydrolysis
E) phosphorylation : condensation

Question 15

Which of the following statements best represents the second law of thermodynamics?

A) Stored energy can eventually be converted to kinetic energy.
B) Natural processes tend to proceed in the direction that expands the energy.
C) Metabolic reactions are the sum of all the reactions in the body.
D) Energy is neither created nor destroyed.
E) Energy is the capacity to do work.

Question 16

The addition of two hydrogens and two electrons to NAD⁺ is an example of what type of chemical reaction?

A) reduction
B) condensation
C) oxidation
D) hydrolysis
E) phosphorylation

Question 17

Chemical reactions that involve the formation of peptide bonds between amino acids that produce water as a byproduct are called

A) hydrolysis
B) condensation
C) phosphorylation
D) reduction
E) oxidation

Question 18

In the chemical equation A + B "C + D, the arrow indicates that the reaction is

A) unidirectional.
B) a metabolic pathway.
C) bidirectional.
D) the net reaction of A+B.
E) None of the answers is correct.

Question 19

Which of the following statements about chemical equilibrium is FALSE?

A) At equilibrium, the concentration of products equals the concentration of reactants.
B) Adding an enzyme will not alter the equilibrium.
C) Decreasing the amount of product will increase the production of product.
D) At equilibrium, the rate of formation of products equals the rate of formation of reactants.
E) Increasing the amount of reactant will increase the production of product.

Question 20

Which of the following is a correct description of an anabolic pathway?

A) Glycogen is synthesized in the cytosol from glucose.
B) The primary site of the synthesis of triglycerides is in the liver.
C) Proteins are degraded by mRNA in the cytoplasm.
D) The primary site of the breakdown of triglycerides is in the adipose tissue.
E) Proteins are transcribed from DNA in the nucleus.

Question 21

Coenzyme A is derived from which of the following vitamins?

A) niacin
B) vitamin A
C) riboflavin
D) pantothenic acid
E) vitamin C

Question 22

The rate at which an enzyme -catalyzed reaction occurs can be increased by

A) increasing enzyme concentration.
B) decreasing substrate concentration.
C) releasing the cofactor that was bound to the enzyme. of the
Site
D) changing the enzyme's conformation, thereby reducing its affinity for the substrate.
E) decreasing temperature.

Question 23

Enzymes are what class of molecule?

A) nucleic acids
B) carbohydrates
C) trace metals
D) lipids
E) proteins

Question 24

Molecules must have sufficient potential energy to overcome the reaction to proceed.

A) activation energy barrier
B) mass action
C) transitional energy barrier
D) transformation state
E) kinetic energy

Question 25

The measure of how many product molecules can be produced by an enzyme per unit of time is referred to as that enzyme's

A) coenzyme rate.
B) affinity.
C) catalytic rate.
D) cofactor rate.
E) specificity.

Question 26

A substrate is the same as a

A) solute.
B) liquid.
C) ligand.
D) reactant.
E) product.

Question 27

In the induced -fit model for enzyme activity, the substrate alters the on the enzyme.

A) conformation : active
B) shape : allosteric
C) conformation : allosteric
D) conformation : inactive
E) activity : active

Question 28

Reaction rates higher or lower than required by the body lead to disease states. How does the body regulate its metabolic needs?

A) Reaction rates are regulated to match the body's needs at a particular moment.
B) The control center maintains a constant temperature so reaction rates remain the same.
C) Product is produced faster than substrate.
D) Reactants and products are at equilibrium.
E) Reactions move in the forward direction to produce product.

Question 29

Some enzymes require trace metals to function as cofactors. What do the trace metals do?

A) Trace metals provide energy for the reaction.
B) Trace metals covalently modulate the enzyme.
C) Trace metals are necessary for the transfer of electrons between substrates.
D) Trace metals are necessary for the transfer of uncharged chemical groups between substrates.
E) Trace metals must be present in the enzyme in order for the enzyme to bind substrate.

Question 30

Which of the following would NOT increase the rate of a chemical reaction?

A) adding an enzyme
B) increasing the temperature
C) adding a catalyst
D) increasing the concentration of reactants
E) increasing the activation energy barrier

Question 31

Decreasing temperatures will the reaction rate.

A) not alter : increasing
B) not alter : not changing
C) increase : increasing
D) decrease : decreasing
E) increase : decreasing

Question 32

Which of the following would decrease the rate of an enzyme -catalyzed reaction?

A) increasing the concentration of product
B) increasing the concentration of substrate
C) increasing the affinity of the enzyme for its substrate
D) increasing the kinetic energy
E) increasing the concentration of enzyme

Question 33

The greater the attractive forces between substrate and enzyme, that enzyme is said to have a higher

A) affinity for the substrate.
B) cofactor activity
C) coenzyme activity
D) repulsion
E) catalytic rate

Question 34

How do enzymes speed up chemical reactions?

A) by making sure the enzyme is part of the product
B) by lowering the temperature, thereby reducing friction
C) by lowering the activation energy barrier
D) by converting kinetic energy back to potential energy
E) by increasing the activation energy barrier

Question 35

What are coenzymes?

A) inorganic molecules derived from trace metals that function in the transfer of a chemical group
B) inorganic molecules derived from vitamins that function in the transfer of a chemical group
C) organic molecules derived from trace metals that function in the transfer of a chemical group
D) organic molecules derived from vitamins that function in the transfer of a chemical group
E) protein complexes that function as enzymes with more than one active site

Question 36

The enzyme carbonic anhydrase catalyzes the following reaction: CO₂ + H₂O -H₂CO₃, then H₂CO₃ dissociates reversibly to form H⁺ + HCO₃ ^-
When tissue becomes more active, carbon dioxide increases due to its production in ,
Causing hydrogen ion concentration to .

A) the cytosol : decrease
B) the cytosol : increase
C) mitochondria : increase
D) mitochondria : decrease
E) both the cytosol and mitochondria : decrease

Question 37

Enzymes act as

A) an energy source
B) catalysts
C) intermediates
D) reactants
E) products

Question 38

Not all enzymes have substrate specificity. For example, pepsin can breakdown numerous types of proteins in the stomach. What concept best describes why the single enzyme pepsin can breakdown so many proteins?

A) the law of mass action
B) the induced -fit model
C) complementary base pairing rule
D) ligand -protein interactions
E) the lock -and -key model

Question 39

An energy -releasing reaction is referred to as an _

A) activation
B) equilibrium
C) exchange
D) exergonic
E) endergonic

Question 40

As the energy required to overcome the activation energy barrier increases, the reaction rate will

A) remain unaltered.
B) decrease.
C) increase.
D) depend solely upon temperature.
E) occur more frequently.

Question 41

Where does glycolysis occur?

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

Question 42

Which of the following does NOT occur in mitochondria?

A) production of carbon dioxide
B) Krebs cycle
C) oxidative phosphorylation
D) consumption of oxygen
E) conversion of pyruvate to lactate

Question 43

What is the major physiological importance of breathing?

A) We need oxygen to survive.
B) It eventually produces water, which we need to survive.
C) We need to eliminate CO₂ from our system because it is a waste product.
D) We need to control our core temperature by breathing in oxygen from the environment.
E) Oxygen must be present in our cells to break down food into energy.

Question 44

If the graph of an enzyme -catalyzed reaction shows a sigmoidal relationship between substrate concentration and reaction rate, then what can be said about the reaction?

A) It is allosterically regulated.
B) It is part of an oxidation -reduction process.
C) It is covalently regulated.
D) It is exergonic.
E) It is endergonic.

Question 45

In a metabolic pathway, the enzyme working the slowest in that pathway is known as the enzyme.

A) binding
B) inhibitor
C) rate -limiting
D) modulating
E) allosteric regulating

Question 46

ATP is synthesized by substrate -level phosphorylation during which of the following?

A) glycolysis only
B) conversion of pyruvate to lactate only
C) Krebs cycle only
D) glycolysis and the Krebs cycle only
E) glycolysis, the Krebs cycle, and during conversion of pyruvate to lactate

Question 47

Regulation of an enzyme through reversible binding of a modulator to a regulatory site on an enzyme is specifically called

A) the lock -and -key model.
B) pH regulation
C) allosteric regulation.
D) covalent regulation.
E) the induced -fit model.

Question 48

Many drugs are manufactured that tend to bind to an enzyme's active site more quickly than the substrate the enzyme normally binds. What quality allows the drug to be attracted to the active site more readily than the substrate?

A) saturation
B) competition
C) affinity
D) chemical specificity
E) the lock -and -key model

Question 49

In skeletal muscle, ATP can be synthesized by transferring a phosphate group from creatine -P to ADP to form ATP and creatine. In this example, ATP was synthesized by what process?

A) oxidation
B) substrate -level phosphorylation
C) reduction
D) oxidative phosphorylation
E) condensation

Question 50

In allosteric regulation, the modulator molecule binds to the

A) regulatory site of the enzyme by weak, reversible interactions.
B) catalytic site of the enzyme by weak, reversible interactions.
C) catalytic site by covalent bonds.
D) cofactor by weak, reversible interactions.
E) regulatory site by covalent bonds.

Question 51

Enzymes are proteins. If the enzyme concentration is increased, the rate of activity of the enzyme will increase exponentially as long as there is substrate to bind. How does the body increase the enzyme concentration?

A) through DNA replication
B) by increasing the catalytic rate
C) by increasing the body's core temperature
D) through protein synthesis
E) through feedback inhibition

Question 52

During end -product inhibition,

A) the final product of an enzyme -catalyzed reaction inhibits the rate -limiting enzyme via allosteric regulation.
B) the product of the rate -limiting step of an enzyme -catalyzed reaction inhibits the rate -limiting enzyme via covalent regulation.
C) the product of the rate -limiting step of an enzyme -catalyzed reaction inhibits the rate -limiting enzyme via allosteric regulation.
D) the initial substrate of an enzyme -catalyzed reaction inhibits the rate -limiting enzyme via allosteric regulation.
E) the final product of an enzyme -catalyzed reaction inhibits the rate -limiting enzyme via covalent regulation.

Question 53

A protein kinase catalyzes which of the following types of chemical reactions?

A) phosphorylation
B) hydrolysis
C) condensation
D) dephosphorylation
E) oxidation

Question 54

Regulating an enzyme through protein kinase -induced phosphorylation of that enzyme is an example of

A) covalent regulation.
B) the induced -fit model.
C) allosteric regulation.
D) feedback inhibition.
E) cofactor regulation.

Question 55

A drug that blocks the active site of an enzyme and does not allow a product to be produced is known as a(n)

A) allosteric activator.
B) covalent regulator.
C) feedback inhibitor.
D) allosteric inhibitor.
E) protein kinase.

Question 56

The final product of glycolysis under aerobic conditions is pyruvate. What happens to pyruvate under aerobic conditions?

A) Pyruvate provides electrons to the electron transport chain.
B) Pyruvate is converted into acetyl CoA in the cytosol, and the acetyl CoA then enters the mitochondrial matrix.
C) Pyruvate is converted to lactic acid in the mitochondrial matrix.
D) Pyruvate is converted to lactic acid in the cytosol.
E) Pyruvate enters the mitochondrial matrix where it is converted into acetyl CoA.

Question 57

What is the most important energy -transferring compound in cells?

A) fructose
B) protein
C) adenosine triphosphate
D) glucose
E) deoxyribonucleic acid

Question 58

Which of the following statements about end -product inhibition is FALSE?

A) The enzyme modulated is often the rate -limiting enzyme.
B) The amount of product produced is increased by this process.
C) It usually involves allosteric modulation of an enzyme.
D) The last product of a metabolic pathway inhibits the activity of an enzyme earlier in that path.
E) It is an example of negative feedback.

Question 59

In a metabolic pathway, both _ help to keep reaction rates within normal ranges by either speeding them up or slowing them down.

A) coenzymes and cofactors
B) ligand and protein interactions
C) feedforward activation and feedback inhibition
D) affinity and substrate concentration
E) lock -in -key and induced -fit models

Question 60

The complete oxidation of glucose releases how many kcal of energy for every mole of glucose?

A) 7
B) 266
C) 98
D) 686
E) 420

Question 61

Each time an electron is passed between the molecules of the electron transport chain,

A) energy is released.
B) oxygen accepts the electrons.
C) an ATP molecule is produced.
D) energy is gained.
E) carbon dioxide is produced.

Question 62

In terms of energy production, the Krebs cycle is significant because it

A) reduces the coenzymes NAD and FAD for oxidative phosphorylation.
B) produces acetylcoenzyme A for fatty acid synthesis.
C) breaks down glucose.
D) directly produces large amounts of ATP.
E) provides acetylcoenzyme A for glucose synthesis.

Question 63

ATP synthase is able to use the potential energy that originates from

A) the phosphorylation of cytochromes
B) complex I
C) the hydrogen gradient across the inner mitochondrial membrane
D) the sodium gradient across the inner mitochondrial membrane
E) complex IV

Question 64

What is the first component of the electron transport chain that accepts electrons from an NADH molecule?

A) cytochrome a₃
B) cytochrome b
C) coenzyme Q
D) flavin mononucleotide
E) flavin adenine dinucleotide

Question 65

What is the first component of the electron transport chain that accepts electrons from an FADH₂ molecule?

A) flavin mononucleotide
B) coenzyme Q
C) cytochrome a₃
D) cytochrome b
E) flavin adenine dinucleotide

Question 66

Hydrogen ions activate the enzyme ATP synthase by moving from

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

Question 67

Glycogen in muscle is used to

A) convert glucose to fats.
B) contribute to the maintenance of blood glucose.
C) fuel the activity of that muscle exclusively.
D) convert glucose to amino acids.
E) both fuel muscle activity and maintain blood glucose.

Question 68

Under anaerobic conditions, which of the following is a final product of glucose catabolism?

A) carbon dioxide
B) lactic acid
C) pyruvic acid
D) acetyl coenzyme A
E) water

Question 69

Cyanide is a deadly poison that attaches to cytochrome c oxidase, the last protein in the electron transport chain before the terminal electron acceptor. Based on your knowledge of the electron transport chain, which statement below best describes the action of cyanide on the body?

A) Cyanide does not allow H⁺ ions to be pumped into the outer membrane of the mitochondria and, therefore, they are never able to go down their concentration gradient and produce ATP.
B) Cyanide does not allow the Krebs cycle to be completed by blocking acetyl CoA from entering this cycle. This action shuts down the entire process of cellular metabolism.
C) Cyanide blocks the terminal electron acceptor, oxygen, causing an accumulation of CO₂ in the tissues from cellular metabolism, and poisons the system due to excess waste products.
D) Cyanide prevents NADH and FADH₂ from dropping off their electrons at the beginning of the electron transport chain by causing a backup of electrons in the Krebs cycle.
E) Cyanide blocks the terminal electron acceptor oxygen and therefore will halt the production of ATP. The majority of ATP is normally produced in the electron transport chain and without it the body will begin to only go through glycolysis and start producing lactic acid and will eventually shut down due to a lack of ATP to run the body and because of the buildup of acid in the system.

Question 70

What is the net energy yield for the anaerobic metabolism of one glucose molecule?

A) two molecules of ATP and two NADH
B) two molecules of ATP and 0 NADH
C) two molecules of NADH and 0 ATP
D) two molecules of ATP and three NADH
E) 36 molecules of ATP and 0 NADH

Question 71

What is the final acceptor of electrons in the electron transport?

A) pyruvate
B) water
C) glucose
D) oxygen
E) carbon dioxide

Question 72

Chemiosmotic coupling refers to

A) coupling of the Krebs cycle to the electron transport chain.
B) chemical coupling between substrate and enzymes.
C) chemical coupling of each reaction within the mitochondria.
D) the transfer of a phosphate group from one molecule to another.
E) the harnessing of energy from the reactions of the electron transport chain to make ATP.

Question 73

Where is the electron transport chain?

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

Question 74

Where are the enzymes of glycolysis located within the cell?

A) outer mitochondrial membrane
B) inner mitochondrial membrane
C) cytosol
D) lysosome
E) nucleus

Question 75

Under low oxygen conditions, the production of ATP. must unload its electrons to allow glycolysis to continue

A) lactate
B) pyruvate
C) NAD⁺ D) NADH
E) FADH₂

Question 76

How many ATP are generated per acetyl coenzyme A going through the Krebs cycle followed by the electron transport system?

A) 12
B) 36 -38
C) 24
D) 2
E) 3

Question 77

How is glucose stored in muscle and liver cells?

A) glycogen
B) amino acids
C) cellulose
D) starch
E) lipids

Question 78

Under anaerobic conditions, what is pyruvate converted to and where does this occur?

A) acetyl coenzyme A in the mitochondria
B) lactate in the mitochondria
C) lactate in the cytosol
D) acetyl coenzyme A in the cytosol
E) fatty acid in the cytosol

Question 79

In the presence of a limited oxygen supply, pyruvate is converted to what?

A) glucose
B) NADH
C) lactate
D) acetyl CoA
E) ATP

Question 80

In the presence of oxygen, the process of glycolysis produces which of the following products?

A) 2 lactate
B) 2 pyruvate
C) 1 pyruvate
D) 2 glycerol
E) 1 lactate