Deck 21: Carbohydrate Metabolism

Question 1

Which pathway is NOT correctly identified as anabolic or catabolic?

A)The digestion of starch is a catabolic process.
B)The synthesis of proteins from amino acids is an anabolic process.
C)The oxidation of glucose to CO₂ and H₂O is a catabolic process.
D)The formation of ADP from ATP is an anabolic process.
E)The conversion of glycogen to glucose is a catabolic process.

Answer 1

The formation of ADP from ATP is an anabolic process.

Question 2

When one molecule of glucose undergoes glycolysis followed by lactate fermentation,what happens to the net number of NAD⁺ and NADH molecules?

A)The number of NAD⁺ molecules increases,and the number of NADH molecules decreases.
B)The number of NAD⁺ molecules decreases,and the number of NADH molecules increases.
C)The number of NAD⁺ molecules decreases,and the number of NADH molecules decreases.
D)The number of NAD⁺ molecules increases,and the number of NADH molecules increases.
E)There is no net change in the number of molecules of either NAD⁺ or NADH.

Answer 2

There is no net change in the number of molecules of either NAD⁺ or NADH.

Question 3

ATP is a ribonucleotide triphosphate.Which of the following correctly represents the structure of ATP?

A)

B)

C)

D)

E)

Answer 3

Question 4

In the first step of glycogenolysis,the enzyme glycogen phosphorylase acts on glycogen to produce glucose-1-phosphate.What must happen to this product before it can enter the glycolysis pathway?

A)It must transfer its phosphate group to ADP.
B)It must add another phosphate group from ATP.
C)It must isomerize to glucose-6-phosphate.
D)It must become activated by binding to UDP.
E)It must become bound to acetyl-CoA.

Question 5

Aldolase splits fructose-1,6-bisphosphate into two compounds.One is glyceraldehyde-3-phosphate.What is the other product of this reaction?

A)glyceraldehyde-2-phosphate
B)glyceraldehyde-1-phosphate
C)dihydroxyacetone phosphate
D)phosphoenolpyruvate
E)1,3-bisphosphoglycerate

Question 6

What is an important result of the lactate and ethanol fermentation processes?

A)Glucose is oxidized to CO₂ and water,providing energy for the synthesis of ATP.
B)NADH is reoxidized to NAD⁺,which allows glycolysis to continue.
C)The CO₂ produced in glycolysis is used up and converted to O₂.
D)Ethanol is converted to CO₂ and water,providing energy for the synthesis of ATP.
E)Glucose is regenerated in these processes,and allowed to enter into glycolysis.

Question 7

What are the two ways in which the energy of a food source can be released in a catabolic pathway?

A)chemical bond energy and light
B)heat and light
C)chemical bond energy and heat
D)electrons and enzymes
E)phosphate and enzymes

Question 8

The primary function of catabolic pathways is the generation of a particular substance.What is this substance?

A)O₂
B)inorganic phosphate
C)ATP
D)glucose
E)AMP

Question 9

The abbreviated form of the equation for breaking the phosphoanhydride bond of ATP is shown below.What is the missing product in this reaction? ATP → ADP + ? + 7 kcal/mol

A)AMP
B)water
C)an inorganic phosphate group or P_i
D)NAD⁺
E)energy

Question 10

The abbreviated form of the equation for the first reaction of glycolysis is shown below.What is the missing product in this reaction? glucose + P_i + 3 kcal/mol → water + ?

A)ATP
B)glucose-6-phosphate
C)an inorganic phosphate group
D)hexokinase
E)glucose triphosphate

Question 11

What hydrolysis product of fats is converted into glyceraldehyde-3-phosphate so that it may enter the glycolysis pathway?

A)glucose
B)glycerol
C)fructose
D)amino acids
E)ethanol

Question 12

What substrate is converted into fructose-1,6-bisphosphate by the enzyme phosphofructokinase?

A)fructose
B)fructose-6-phosphate
C)glucose-6-phosphate
D)glucose-1,6-bisphosphate
E)fructose triphosphate

Question 13

Which of the following statements concerning metabolism is FALSE?

A)Metabolism refers to all of the chemical reactions that take place in living cells.
B)Anabolism involves the synthesis of larger molecules from smaller ones; catabolism involves the breaking down of larger molecules into smaller ones.
C)Anabolic reactions are endergonic reactions,and catabolic reactions are exergonic reactions.
D)The energy required for catabolic reactions is provided by the energy released from anabolic reactions.
E)The human body utilizes both anabolic and catabolic reactions.

Question 14

The hormone insulin stimulates which of the following biochemical pathways?

A)glycogenesis
B)gluconeogenesis
C)glycogenolysis
D)glycolysis
E)reoxidation of NADH

Question 15

In what stage of catabolism is the most ATP produced?

A)Stage I
B)Stage II
C)Stage III
D)It depends on the type of food ingested.
E)All stages produce an equal amount of ATP.

Question 16

What is the first reaction in glycolysis,which traps glucose within the cell?

A)oxidation of glucose
B)hydrolysis of glucose
C)hydrogenation of glucose
D)phosphorylation of glucose
E)dehydration of glucose

Question 17

What term describes the synthesis of glucose from non-carbohydrate sources?

A)glycolysis
B)glycogenolysis
C)glucosidase
D)gluconeogenesis
E)glycogenesis

Question 18

Digestion of carbohydrates begins in the mouth with the aid of what enzyme?

A)glucase
B)pepsin
C)ATP
D)amylase
E)NAD⁺

Question 19

The hormones glucagon and epinephrine primarily control which biochemical pathway?

A)glycolysis
B)digestion
C)glycogenolysis
D)glycogenesis
E)oxidative phosphorylation

Question 20

What is meant by the term catabolism?

A)the total of all chemical reactions within the human body
B)the formation of glucose and other important biomolecules
C)the synthesis of glucose from noncarbohydrate compounds
D)the degradation (breakdown)of molecules with an accompanying release of energy
E)the biosynthesis (buildup)of molecules with an accompanying release of energy

Question 21

Of the several high-energy compounds produced in cells,which one is the principal energy storage compound?

A)ATP
B)AMP
C)glucose-6-phosphate
D)glycerol
E)glucose

Question 22

The last step of glycolysis is the kinase catalyzed reaction represented below.What is the identity of the missing product? phosphoenolpyruvate + ADP → ATP + ?

A)P_i
B)AMP
C)glucose
D)pyruvate
E)glycogen

Question 23

What hormone is released from the pancreas in response to low blood glucose levels?

A)insulin
B)epinephrine
C)estrogen
D)glucagon
E)testosterone

Question 24

Which enzyme catalyzes the hydrolysis of dietary proteins in the stomach?

A)lactase
B)pepsin
C)lipase
D)amylase
E)insulin

Question 25

The end product of glycolysis is pyruvate.What condition inside the cell is needed to convert pyruvate to acetyl CoA for entry into the citric acid cycle?

A)sufficient oxygen
B)anaerobic conditions
C)yeast
D)high CO₂
E)All of these are correct.

Question 26

Which organ is the main site of gluconeogenesis?

A)gall bladder
B)pancreas
C)small intestine
D)stomach
E)liver

Question 27

Which coenzyme form must be reoxidized so that glycolysis can continue to produce ATP for the cell?

A)NADP⁺
B)NADH
C)NADPH
D)FADH
E)FADH₂

Question 28

Which of the following statements concerning the digestion of food groups is FALSE?

A)Digestion of all food groups begins in the mouth.
B)Carbohydrates are broken down into glucose and other monosaccharides.
C)Fats are broken down into glycerol and fatty acids.
D)Proteins are broken down into amino acids.
E)Polysaccharides are broken down into glucose and other monosaccharides.

Question 29

How many NADH are produced for each glucose molecule that enters glycolysis?

A)1
B)2
C)4
D)6
E)8

Question 30

Approximately how much energy,in kilocalories/mol,is released by one mole of ATP in the reaction shown below? ATP + water → ADP + P_i + energy

A)7
B)15
C)32
D)700
E)1000

Question 31

What is the net yield of ATP molecules per glucose molecule undergoing glycolysis?

A)2
B)4
C)8
D)16
E)686

Question 32

What is the identity of the missing product in the kinase catalyzed reaction shown below? 1,3-bisphosphoglycerate + ADP → 3-phosphoglycerate + ?

A)PP_i
B)ATP
C)AMP
D)A
E)water

Question 33

Why is the pentose phosphate pathway important?

A)It produces more ATP molecules than any other biochemical pathway.
B)It is an alternate pathway for glucose oxidation,and provides important molecules such as NADPH and sugar phosphates.
C)It is an alternate pathway for the production of glucose and energy.
D)It serves as the primary pathway for the reoxidation of NADH to NAD⁺.
E)It converts 5-carbon sugars to 6-carbon sugars,thereby allowing them to enter into the glycolysis pathway.

Question 34

When one molecule of glucose undergoes glycolysis followed by alcohol fermentation,what products,and how many molecules of each of them,account for the 6 carbon atoms?

A)6 molecules of carbon dioxide and 6 molecules of water
B)2 molecules of ethanol and 2 molecules of carbon dioxide
C)1 molecule of ethanol,3 molecules of carbon dioxide,and 3 molecules of water
D)6 molecules of carbon monoxide and 6 molecules of water
E)None of the choices are correct.

Question 35

Which pathway is believed to be the first successful pathway for harvesting energy to have evolved on Earth?

A)glycogenesis
B)Krebs Cycle
C)glycolysis
D)pentose phosphate pathway
E)lactate fermentation

Question 36

Which enzyme catalyzes the hydrolysis of milk sugar?

A)lipase
B)hydrolase
C)lactose
D)lactase
E)peptase

Question 37

What polymer is the principal storage form of glucose?

A)glycogen
B)cellulose
C)starch
D)DNA
E)insulin

Question 38

Step 7 in glycolysis is shown below.Which statement concerning this step is TRUE?

A)Breaking the phosphoanhydride bond of ATP provides the energy necessary for the removal of a phosphate group from 1,3-bisphosphoglycerate.
B)The hydrolysis of 1,3-bisphosphoglycerate provides the energy necessary for the phosphorylation of ADP.
C)The energy required for the hydrolysis of 1,3-bisphosphoglycerate is stored in ADP.
D)The hydrolysis of 1,3-bisphosphoglycerate provides the energy necessary for breaking the phosphoanhydride bond of ATP.
E)The phosphorylation of 1,3-bisphosphoglycerate is driven by the phosphorylation of ADP.

Question 39

Breaking the phosphoanhydride bond of ATP can be used to "drive" a reaction.What does this mean?

A)ATP acts as a carrier molecule for substrates in reactions.
B)The ATP produced from breaking the phosphoanhydride bond acts as a catalyst to increase the rates of otherwise slow biochemical processes.
C)The energy produced from breaking the phosphoanhydride bond of ATP is used by energy-requiring reactions in the body.
D)Breaking the phosphoanhydride bond of ATP yields a phosphate group that is used as a cofactor in enzyme-catalyzed reactions in the body.
E)Breaking the phosphoanhydride bond of ATP activates the effector site on allosteric enzymes,which can then be used to catalyze reactions.

Question 40

At the end of glycolysis,how many pyruvate molecules have been produced from 10 glucose molecules?

A)20
B)60
C)120
D)140
E)360

Question 41

Which of the statements concerning gluconeogenesis is FALSE?

A)Gluconeogenesis is the process by which glucose is synthesized from carbon atoms from noncarbohydrate sources.
B)Gluconeogenesis is a pathway that protects the brain and red blood cells from experiencing a loss of glucose.
C)The gluconeogenesis pathway is the reverse of glycolysis.
D)Gluconeogenesis is a pathway that is utilized when vigorous activity depletes blood glucose and glycogen stores.
E)The level of carbohydrate available from the diet controls gluconeogenesis; the gluconeogenesis pathway is active for a diet low in carbohydrates,and inactive for a diet high in carbohydrates.

Question 42

The last step in alcohol fermentation involves the reduction of acetaldehyde and the oxidation of NADH.What is the structure of the reduction product?

A)

B)

C)

D)CH₃CH₂OH
E)CH₃CH₃

Question 43

The enzyme triose phosphate isomerase catalyzes the isomerization of dihydroxyacetone phosphate.What is the product of this reaction?

A)lactate
B)pyruvate
C)fructose-6-bisphosphate
D)glyceraldehyde-3-phosphate
E)glucose-1,6-bisphosphate

Question 44

What is the reducing agent for the conversion of pyruvate into lactate in muscle tissue?

A)NAD⁺
B)NADPH
C)NADH
D)FAD
E)FADH₂

Question 45

What is the function of coenzyme A?

A)to carry acetyl groups in the form of acetyl CoA to the citric acid cycle
B)to oxidize carbohydrates in glycolysis
C)to hydrolyze triglycerides to produce fatty acids and glycerol
D)to carry phosphate groups to glycolysis
E)to carry ADP to the citric acid cycle

Question 46

Excess glucose is stored in the body as glycogen.Where are these glycogen reserves primarily found?

A)brain and red blood cells
B)red blood cells and liver
C)adipose tissue and brain
D)liver and skeletal muscles
E)kidneys and fat cells

Question 47

Which statement concerning glycogenolysis is FALSE?

A)It is the process by which glycogen is broken down into glucose.
B)It is a pathway that provides the brain and muscle with free glucose.
C)It has the effect of raising blood glucose levels.
D)It is utilized when vigorous activity depletes blood glucose levels.
E)It is activated by the secretion of insulin into the bloodstream.

Question 48

What key reducing agent is formed in the pentose phosphate pathway for glucose oxidation?

A)ATP
B)NAD⁺
C)NADH
D)NADP⁺
E)NADPH

Question 49

Which statement best describes how the interconversion of ATP and ADP is responsible for storing and providing energy for cellular reactions?

A)Energy is stored in ADP and released when ADP adds a phosphate group.
B)Energy is stored in ADP and released when the phosphoanhydride bond of ATP is broken.
C)Energy is stored in ATP and released when ADP undergoes phosphorylation.
D)Energy is stored in ATP and released when the phosphoanhydride bond of ATP is broken.
E)Energy requiring reactions of the cell drive the phosphorylation of ADP.

Question 50

What substrate is converted into glucose-6-phosphate by the enzyme hexokinase?

A)fructose
B)glycogen
C)glucose
D)pyruvate
E)lactate

Question 51

In glycogen synthesis,glycogen synthase catalyzes the linking of glucose units to the growing glycogen chain by the formation of α (1,4)glycosidic bonds.What is the immediate source of glucose for this reaction?

A)ATP-glucose
B)ADP-glucose
C)UTP-glucose
D)UDP-glucose
E)glucose-6-phosphate

Question 52

Which of the following is a true statement concerning breaking the phosphoanhydride bond of ATP to form ADP?

A)Energy is released,which can drive biological processes.
B)Water is formed because the breaking of the bond is a hydrolysis process.
C)It is an endothermic process because of the formation of glucose-6-phosphate.
D)Energy is stored.
E)Hundreds of kJ/mol are released in the form of heat.

Question 53

What compound is produced during strenuous exercise,when the muscles are depleted of oxygen?

A)pyruvate
B)NADPH
C)lactate
D)ethanol
E)carbon dioxide

Question 54

Which of the following statements concerning ATP is FALSE?

A)ATP is considered the universal energy currency in cells.
B)ATP is a nucleotide triphosphate.
C)ATP contains a phosphoester bond.
D)ATP contains the sugar deoxyribose.
E)The three phosphoryl groups of ATP are joined by phosphoanhydride bonds.

Question 55

What occurs in Stage II of catabolism?

A)Lipids are broken down into glycerol and fatty acids.
B)Proteins are broken down into amino acids.
C)Food molecules are oxidized to CO₂,H₂O,and energy for ATP synthesis.
D)Polysaccharides are broken down to monosaccharides.
E)The products of digestion are further broken down into smaller molecules.

Question 56

The liver takes up excess lactate from the blood.Into what product is the lactate first converted?

A)glucose
B)pyruvate
C)oxaloacetate
D)acetyl CoA
E)glycogen

Question 57

What substance is converted into fructose-6-phosphate by the enzyme phosphoglucoisomerase?

A)glucose-1,6-bisphosphate
B)pyruvate
C)lactate
D)glycerol
E)glucose-6-phosphate

Question 58

Into what final product is glucose converted at the end of glycolysis?

A)lactate
B)phosphoenolpyruvate
C)starch
D)glycogen
E)pyruvate

Question 59

In the first substrate-level phosphorylation in glycolysis,a phosphoryl group is transferred from 1,3-bisphosphoglycerate to ADP,thus producing ATP.What is the other product of this reaction?

A)3-phosphoglycerate
B)2-phosphoglycerate
C)phosphoenolpyruvate
D)pyruvate
E)lactate

Question 60

Step 3 in glycolysis is shown below.Which of the following statements concerning this process is true?

A)Breaking the phosphoanhydride bond of ATP provides the phosphoryl group and the necessary energy for the formation of fructose-1,6-bisphosphate.
B)The formation of fructose-1,6,-bisphosphate provides the necessary energy for breaking the phosphoanhydride bond of ATP.
C)The energy released in the phosphorylation of fructose-6-phosphate is stored in ADP.
D)The phosphorylation of fructose-6-phosphate is an exergonic reaction.
E)The phosphorylation of ADP provides the energy necessary for the formation of fructose-1,6-bisphosphate.

Question 61

Which statement concerning glycolysis is FALSE?

A)Glycolysis is an anaerobic process that occurs in the cytoplasm of the cell.
B)Glycolysis requires energy provided by ATP.
C)Glycolysis is a pathway that consists of ten enzyme catalyzed reactions.
D)Glycolysis is the final step in the process to produce energy from food.
E)Glycolysis breaks down glucose into two pyruvate molecules.

Question 62

Skeletal muscle cannot contribute to blood glucose as it lacks the enzyme necessary to convert glucose-6-phosphate to glucose.

Question 63

Stage I of catabolism produces the most ATP.

Question 64

In glycolysis,a molecule of glucose is converted into 2 molecules of lactate.

Question 65

The blood of an average 70 kg human being contains about 20 g of glucose.

Question 66

In the Cori Cycle,lactate produced in muscles is transported to the liver where it is converted to glucose and returned to the muscles.

Question 67

ATP,the universal energy currency of the cell,stands for adenosine triphosphate.

Question 68

Glycogenesis occurs under which of the following conditions?

A)when digestion of polysaccharides provides high levels of blood glucose
B)when blood glucose levels are low
C)when blood glucose is completely depleted due to strenuous exercise
D)when epinephrine is released from the adrenal glands
E)when glucose is needed for energy by the brain and muscles

Question 69

The end products of fermentation are ethylene glycol and carbon dioxide.

Question 70

The energy released from the oxidation of the food we eat can be used to form ATP.

Question 71

Gluconeogenesis involves the production of glycogen from a noncarbohydrate source.

Question 72

Red blood cells rely exclusively on lactate as their energy source.

Question 73

In alcohol fermentation,yeast converts ethanol into acetic acid.

Question 74

The formation of glucose-6-phosphate from glucose in a liver cell effectively traps the glucose within the cell.

Question 75

The pentose phosphate pathway is an alternate pathway for glucose oxidation.

Question 76

Yogurt is produced by lactate fermentation by bacteria.