Deck 22: Carbohydrate Metabolism

Question 1

The most important monosaccharide for energy production is

A)glucose.
B)galactose.
C)fructose.
D)ribose.
E)mannose.

Answer 1

glucose.

Question 2

The major products of carbohydrate digestion are

A)monosaccharides and disaccharides.
B)monosaccharides.
C)acetyl CoA.
D)pyruvic acid.

Answer 2

monosaccharides.

Question 3

The major function of the pentose phosphate pathway when energy for anabolic reactions is a priority is

A)producing NADPH.
B)producing ribose.
C)meeting the need for large amounts of ATP.
D)providing intermediates for the citric acid cycle.
E)providing intermediates for glycogenesis.

Answer 3

producing NADPH.

Question 4

The major function of the pentose phosphate pathway when nucleic acid synthesis is a priority is

A)producing NADPH.
B)producing ribose.
C)meeting the need for large amounts of ATP.
D)providing intermediates for the citric acid cycle.
E)providing intermediates for glycogenesis.

Question 5

Which of the following is not a product of digestion?

A)amino acids
B)fatty acids
C)glucose
D)glycerol
E)pyruvate

Question 6

Which of the following are produced as a net result of glycolysis?
I.NADH II.NAD⁺ III.ADP IV.ATP

A)I and II
B)III and IV
C)I and III
D)I and IV
E)II and III

Question 7

The pathway followed by glucose when energy is needed is

A)gluconeogenesis.
B)glycogenesis.
C)glycolysis.
D)lipogenesis.
E)the pentose phosphate pathway.

Question 8

The synthesis of glycogen from excess glucose is

A)glycolysis.
B)gluconeogenesis.
C)glycogenesis.
D)glycogenolysis.
E)the pentose phoshate pathway.

Question 9

Which conversion is accomplished during glycolysis?

A)glucose to glycogen
B)glucose to pyruvate
C)starch to glucose
D)pyruvate to glucose
E)glycogen to glucose

Question 10

When a cell's need for NADPH or ribose-6-phosphate exceeds its need for ATP,glucose-6-phosphate is metabolized by

A)gluconeogenesis.
B)glycogenesis.
C)glycolysis.
D)glycogenolysis.
E)the pentose phosphate pathway.

Question 11

All of the chemicals below are associated with the pentose phosphate pathway except

A)glucose 6-phosphate.
B)NADPH.
C)ribose.
D)pyruvate.
E)NADP.

Question 12

All of the following statements concerning digestion are correct except

A)the major chemical reaction in digestion is enzyme-catalyzed hydrolysis of large molecules.
B)digestion begins in the mouth,continues in the stomach,and is completed in the small intestine.
C)digestion can be considered a catabolic process in which bulk food is broken down into individual small molecules.
D)the same enzymes are used in the digestion of carbohydrates,lipids,and proteins.
E)the major physical processes in digestion are mixing,softening,and grinding of food.

Question 13

All of the following statements concerning digestion are correct except

A)digestion can be considered a catabolic process in which bulk food is broken down into individual small molecules.
B)the major chemical reaction in digestion is enzyme-catalyzed hydrolysis of large molecules.
C)the major physical processes in digestion are mixing,softening and grinding of food.
D)digestion begins in the stomach and is completed in the large intestine.
E)different foods are digested by different enzymes.

Question 14

The target molecule(s)for α-amylase is(are)

A)glucose.
B)sucrose.
C)all disaccharides.
D)starch.
E)starch and glycogen.

Question 15

Which polysaccharide is not broken down by α-amylase?

A)glycogen
B)cellulose
C)amylase
D)amylopectin

Question 16

The most important goal of glucose metabolism is

A)synthesis of oxidized coenzymes.
B)synthesis of glycogen for later use.
C)production of ATP as an energy source for all cells.
D)production of acetyl-CoA for synthesis of lipids.
E)synthesis of carbon skeletons for amino acid production.

Question 17

When energy is needed and adequate oxygen is available,pyruvate is converted to

A)glucose.
B)glycogen.
C)lactate.
D)ethanol.
E)acetyl-CoA.

Question 18

In the first step of glycolysis,the conversion of glucose to glucose 6-phosphate is known as

A)isomerization.
B)reduction.
C)oxidation.
D)phosphorylation.
E)dehydration.

Question 19

Classify each pathway of carbohydrate metabolism as anabolic or catabolic.Justify your choice in each case.

Question 20

All of the following are reactions in the oxidation of glucose which produce energy except

A)glycolysis.
B)glycogenolysis.
C)oxidation of pyruvate to acetyl-CoA.
D)the citric acid cycle.
E)reaction of reduced coenzymes in the electron transport chain.

Question 21

Which reaction(s)of glycolysis is(are)key regulation step(s)in the process?

A)formation of fructose-6-phosphate from glucose-6-phosphate
B)formation of glucose-6-phosphate from glucose
C)cleave of fructose-1,6-bisphosphate
D)formation of fructose-1,6-bisphosphate from fructose-6-phosphate
E)Both B and D.

Question 22

Steps 6-10 of glycolysis are referred to as the "energy generation" portion of the process because these steps

A)consume ATP instead of producing it.
B)generate ATP instead of consuming it.
C)involve several endergonic reactions.
D)generate ADP.
E)release phosphate groups upon hydrolysis.

Question 23

The conversion of glucose 6-phosphate to fructose 6-phosphate in the second step of glycolysis is a(an)________ reaction.

A)isomerization
B)reduction
C)oxidation
D)phosphorylation
E)dehydration

Question 24

The pain and cramps that occur during physical exhaustion are associated with the formation of excess

A)lactate.
B)pyruvate.
C)acetyl-CoA.
D)acetaldehyde.
E)glucose.

Question 25

Pyruvate is converted to lactate under anaerobic conditions because

A)reduction of pyruvate provides NAD⁺ which is needed for glycolysis.
B)lactate releases oxygen upon conversion to acetyl-CoA.
C)reduction of pyruvate provides NADH which is needed for gluconeogenesis.
D)lactate is the storage form of pyruvate for use later when more ATP is needed.
E)none of the above

Question 26

The dehydration of 2-phosphoglycerate to phosphoenolpyruvate uses the enzyme

A)pyruvate kinase.
B)phosphoglycerate kinase.
C)enolase.
D)hexokinase.
E)aldolase.

Question 27

The net number of ATP formed when one molecule of glucose is converted to pyruvate is

A)1.
B)2.
C)3.
D)4.
E)5.

Question 28

Steps 1-5 of glycolysis are referred to as the "energy investment" portion of the process because these steps

A)consume ATP instead of producing it.
B)generate waste products which cost ATP for disposal.
C)produce NADH which is less energy-rich than ATP.
D)involve several endergonic isomerizations.
E)none of the above

Question 29

Conversion of dihydroxyacetone phosphate to d-glyceraldehyde 3-phosphate is a(an)

A)isomerization.
B)oxidation.
C)reduction.
D)esterification.
E)condensation.

Question 30

Which of the following monosaccharides is generated during digestion of milk?

A)mannose
B)ribose
C)galactose
D)fructose
E)xylose

Question 31

The products of glycolysis important in metabolism are

A)acetyl-CoA and ATP.
B)pyruvate,ATP,and NADH.
C)CO₂,ATP,and NADH.
D)pyruvate,ADP,and NAD⁺.
E)CO₂ and H₂O.

Question 32

The chemical produced in steps 3-5 of glycolysis and oxidized in step 6 is

A)glucose.
B)acetyl-CoA.
C)glyceraldehyde 3-phosphate.
D)citrate.
E)oxaloacetate.

Question 33

When ATP is produced by direct transfer of a phosphate group instead of from reactions coupled to electron transport,the process is referred to as ________ phosphorylation.

A)oxidative
B)substrate-level
C)reductive
D)anabolic
E)catabolic

Question 34

The enzyme that catalyzes cleavage of fructose 1,6-bisphosphate to dihydroxyacetone phosphate and d-glyceraldehyde-3-phosphate is

A)aldolase.
B)d-glyceraldehyde-3-phosphatase.
C)phosphofructokinase.
D)hexokinase.
E)none of the above

Question 35

Entry of monosaccharides other than glucose into the glycolysis pathway initially involves

A)breakdown into pyruvate.
B)oxidation into acetyl groups.
C)conversion into phosphates.
D)reduction of carbonyl groups.
E)hydrolysis of 2-carbon units.

Question 36

Which chemical is produced from pyruvate when it is metabolized in muscle cells under aerobic conditions?

A)lactate
B)ethanol
C)acetyl-CoA
D)phosphoenol pyruvate
E)glucose

Question 37

Which of the following carbohydrates can also be used as fuel in glycolysis?

A)glucose
B)glucose and fructose
C)fructose and galactose
D)galactose,fructose,and mannose
E)fructose

Question 38

Glycolysis occurs mainly in the

A)cytosol of all cells.
B)mitochondria of all cells.
C)muscle.
D)liver.
E)brain.

Question 39

The first step of glycolysis involves ________ to form ________.

A)esterification;glucose-6-phosphate
B)oxidation;glucose -6-phosphate
C)addition;fructose-1,6-diphosphate
D)esterification;glucose-1-phosphate
E)isomerization;fructose-6-phosphate

Question 40

All of these enzymes used in glycolysis involve the transfer of a phosphate group except

A)hexokinase.
B)aldolase.
C)phosphglycerate kinase.
D)pyruvate kinase.
E)phosphofructokinase.

Question 41

Hormones which regulate glucose metabolism are ________,________,and ________.

A)insulin;cortisone;thyroxine
B)insulin;glucagon;epinephrine
C)estrogen;progesterone;testosterone
D)growth hormone;cortisone;thyroxine
E)estrogen;glucagon;epinephrine

Question 42

Which chemical is produced from pyruvate when it is metabolized in muscle cells under anaerobic conditions?

A)lactate
B)ethanol
C)acetyl-CoA
D)phosphoenol pyruvate
E)glucose

Question 43

If a glucose tolerance test shows an abnormally high level of glucose in the blood after several hours,the person is possibly

A)hypoglycemic.
B)diabetic.
C)anemic.
D)overweight.

Question 44

What are the three possible fates of pyruvate?

Question 45

Which chemical is produced from pyruvate when it is metabolized by yeast cells?

A)lactate
B)ethanol
C)acetyl-CoA
D)phosphoenol pyruvate
E)glucose

Question 46

Glycogenolysis does not occur in muscle tissue because it lacks which of the following enzymes?

A)glucose-6-phosphatase
B)glycogen phosphorylase
C)phosphoglucomutase
D)pyruvate kinase

Question 47

How many ATP are generated from the 10 NADH molecules formed during complete oxidation of glucose?

A)20
B)30
C)38
D)25
E)32

Question 48

Overproduction of insulin causes ________,a state in which the concentration of blood sugar is ________ than normal.

A)hypoglycemia;lower
B)hypoglycemia;higher
C)hyperglycemia;lower
D)hyperglycemia;higher
E)none of the above

Question 49

The diseases identified as diabetes are primarily associated with a malfunction of the hormone

A)glucagon.
B)insulin.
C)epinephrine.
D)cortisone.
E)sorbitol.

Question 50

Insulin increases the rate at which glucose

A)is converted to glycogen.
B)is converted to fat.
C)enters the cell.
D)is converted from glycogen.
E)More than one response is correct.

Question 51

A lack of insulin causes ________,a state in which the concentration of blood sugar is ________ than normal.

A)hypoglycemia;lower
B)hypoglycemia;higher
C)hyperglycemia;lower
D)hyperglycemia;higher
E)none of the above

Question 52

When blood sugar levels are lower than normal,this condition is called

A)hypoglycemia.
B)hyperglycemia.
C)glucosuria.
D)diabetes mellitus.

Question 53

When a body is deprived of glucose it will begin to break down fats in order to conserve protein.As a consequence acetyl-CoA will begin to build up.What compound is this excess by-product converted into?

A)citric acid
B)pyruvate
C)acetone
D)lactate
E)galactose

Question 54

The overall yield of ATP molecules from the complete catabolism of one molecule of glucose in humans and other mammals is

A)18.
B)24.
C)38.
D)42.
E)56.

Question 55

The hormone that stimulates the breakdown of glycogen is

A)glucagon.
B)insulin.
C)epinephrine.
D)cortisone.
E)sorbitol.

Question 56

How many ATP are generated from the 10 NADH and 2 FADH₂ molecules formed during complete oxidation of glucose?

A)20
B)30
C)38
D)25
E)34

Question 57

When a person is deprived of food,in which order does the body use the following sources to produce glucose?
I.protein breakdown to amino acids used for gluconeogenesis
II.conversion of glycogen to glucose
III.catabolism of lipids

A)I,II,III
B)III,II,I
C)II,I,III
D)II,III,I
E)III,I,II

Question 58

The action of yeast on pyruvate is a process referred to as

A)alcoholic fermentation.
B)aerobic oxidation.
C)glycolysis.
D)anaerobic reduction.
E)substrate-level phosphorylation.

Question 59

What cofactor is needed by the pyruvate dehydrogenase complex to convert pyruvate into acetyl CoA?

A)ATP
B)ADP
C)NADH
D)NAD⁺
E)FADH₂

Question 60

In an individual who is starving or fasting,the body meets its need for glucose first by the process of ________,and then by the process of ________.

A)glycolysis;gluconeogenesis
B)glycogenolysis;gluconeogenesis
C)gluconeogenesis;glycogenesis
D)glycogenesis;lipogenesis
E)lipogenesis;glycogenolysis

Question 61

During gluconeogenesis,pyruvate is formed from glycerol,certain amino acids,and

A)acetyl CoA.
B)glucose.
C)lactate.
D)glycogen.

Question 62

Match the following.
glycogenolysis

A)the conversion of glucose into carbohydrate molecules containing phosphate groups and five carbon atoms
B)the conversion of glucose into glycogen
C)the conversion of glycogen into glucose
D)the production of glucose from noncarbohydrate sources
E)the conversion of glucose into pyruvate

Question 63

Which of the following is not used as an energy source in metabolism?

A)ATP
B)UTP
C)UTC
D)GTP
E)More than one choice is correct.

Question 64

Match the following.
glycogenesis

A)the conversion of glucose into carbohydrate molecules containing phosphate groups and five carbon atoms
B)the conversion of glucose into glycogen
C)the conversion of glycogen into glucose
D)the production of glucose from noncarbohydrate sources
E)the conversion of glucose into pyruvate

Question 65

Match the following.
gluconeogenesis

A)the conversion of glucose into carbohydrate molecules containing phosphate groups and five carbon atoms
B)the conversion of glucose into glycogen
C)the conversion of glycogen into glucose
D)the production of glucose from noncarbohydrate sources
E)the conversion of glucose into pyruvate

Question 66

Gluconeogenesis occurs mainly in the

A)cytosol of all cells.
B)mitochondria of all cells.
C)muscle.
D)liver.
E)brain.

Question 67

A high energy phosphate molecule involved in gluconeogenesis is

A)UDP.
B)UTP.
C)GDP.
D)GTP.
E)ADP.

Question 68

The process of making glucose from noncarbohydrates is known as

A)glycolysis.
B)glycogenolysis.
C)gluconeogenesis.
D)glycogenesis.
E)lipogenesis.

Question 69

Match the following.
glycolysis

A)the conversion of glucose into carbohydrate molecules containing phosphate groups and five carbon atoms
B)the conversion of glucose into glycogen
C)the conversion of glycogen into glucose
D)the production of glucose from noncarbohydrate sources
E)the conversion of glucose into pyruvate

Question 70

Glycogenolysis can be correctly represented by which of the following pathways?

A)glucose → glycogen
B)glycogen → glucose
C)pyruvate → glycogen
D)glycogen → pyruvate
E)glucose → pyruvate

Question 71

Glycogen is most commonly found in ________ cells and ________ cells.

A)red blood;white blood
B)red blood;liver
C)muscle;white blood
D)muscle;liver
E)bone;white blood

Question 72

Which pathway produces glucose from its storage form in animals?

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

Question 73

Match the following.
pentose phosphate pathway

A)the conversion of glucose into carbohydrate molecules containing phosphate groups and five carbon atoms
B)the conversion of glucose into glycogen
C)the conversion of glycogen into glucose
D)the production of glucose from noncarbohydrate sources
E)the conversion of glucose into pyruvate