Deck 19: Carbohydrates

Question 1

Including their enantiomeric pairs, how many different 2-ketopentoses are present in nature?

A) two
B) four
C) eight
D) sixteen

Answer 1

B

Question 2

Identify a D-2-ketohexose from among the following compounds.

A) D-xylulose
B) D-ribulose
C) D-erythrulose
D) D-psicose

Answer 2

D

Question 3

Which of the following compounds is a triose?

A) glucose
B) fructose
C) acetone
D) dihydroxyacetone

Answer 3

D

Question 4

Which of the following compounds is a D-aldohexose?

A) D-xylose
B) D-lyxose
C) D-talose
D) D-psicose

Question 5

Identify a D-2-ketopentose from among the following compounds.

A) D-erythrulose
B) D-psicose
C) D-ribulose
D) D-fructose

Question 6

Which of the following statements is true of the hydrolysis of carbohydrates?

A) Carbohydrates do not undergo hydrolysis reactions.
B) The hydrolysis of carbohydrates can only yield polyhydroxyaldehydes.
C) The hydrolysis of carbohydrates can only yield polyhydroxyketones.
D) The hydrolysis of carbohydrates can yield both polyhydroxyaldehydes or polyhydroxyketones.

Question 7

Which of the following is the Fischer projection of D-glyceraldehyde?

A)
B)
C)
D)

Question 8

Which of the following carbohydrates makes up crustacean shells?

A) cellulose
B) chitin
C) glucose
D) glycogen

Question 9

Which of the following is the Fischer projection of L-glyceraldehyde?

A)
B)
C)
D)

Question 10

Which of the following compounds is an aldotetrose?

A) threose
B) ribose
C) arabinose
D) xylose

Question 11

In which pair of aldohexoses do the monosaccharides differ from each other by the position of a single hydroxyl group?

A) D-allose and D-altrose
B) D-altrose and D-glucose
C) D-allose and D-mannose
D) D-mannose and D-idose

Question 12

How many chiral carbons are present in the open-chain form of an aldohexose?

A) three
B) four
C) five
D) six

Question 13

Which carbon atom of a pentose sugar determines whether it has a D or an L configuration?

A) carbon 1
B) carbon 3
C) carbon 4
D) carbon 5

Question 14

Which of the following are the most abundant biological compounds in the plant world?

A) alcohols
B) vitamins
C) carbohydrates
D) proteins

Question 15

Including their enantiomeric pairs, how many different aldopentoses are present in nature?

A) two
B) four
C) eight
D) sixteen

Question 16

Identify a D-aldopentose from among the following compounds.

A) D-psicose
B) D-fructose
C) D-idose
D) D-arabinose

Question 17

What percentage of the body weight of animals is made up of carbohydrates?

A) 1%
B) 5%
C) 10%
D) 15%

Question 18

Including their enantiomeric pairs, how many different 2-ketohexoes are present in nature?

A) two
B) four
C) eight
D) sixteen

Question 19

What is the common molecular formula of carbohydrates?

A) C_n(H₂O)_m
B) C_n(OH)_m
C) (CO)_n(H2O)_n
D) (CO)_n(OH)_m

Question 20

How many chiral carbons are present in the open-chain form of an aldopentose?

A) two
B) three
C) four
D) five

Question 21

In the cyclic structure of fructose, which carbon atoms are connected to the oxygen atom of the furanose ring?

A) carbon 1 and carbon 5
B) carbon 1 and carbon 6
C) carbon 2 and carbon 5
D) carbon 2 and carbon 6

Question 22

Which of the following statements is true of galactosemia?

A) It is an acquired disorder.
B) It occurs because of the inability of the body to metabolize galactose.
C) It does not have any treatment.
D) It involves the conversion of galactose to glucose.

Question 23

Which of the following disaccharides gives fructose on hydrolysis?

A) maltose
B) lactose
C) sucrose
D) cellulose

Question 24

What is an anomeric carbon?

A) the acetal carbon of the cyclic form of a monosaccharide
B) the hemiacetal carbon of the cyclic form of a monosaccharide
C) the acetal carbon of the cyclic form of a disaccharide
D) the hemiacetal carbon of the cyclic form of a disaccharide

Question 25

Who proposed the ring or cyclic structures of monosaccharides?

A) E. Fischer
B) W. Haworth
C) L. Pauling
D) L. Pasteur

Question 26

To which of the following does galactosemia belong?

A) bacterial diseases
B) viral diseases
C) genetic disorders
D) lifestyle disorders

Question 27

RNA and DNA have ribose and deoxyribose sugars, respectively. How are these two sugars different from each other?

A) Unlike ribose, deoxyribose does not have a hydroxyl group at carbon 1.
B) Unlike ribose, deoxyribose does not have a hydroxyl group at carbon 2.
C) Unlike ribose, deoxyribose does not have a hydroxyl group at carbon 3.
D) Unlike ribose, deoxyribose does not have a hydroxyl group at carbon 4.

Question 28

Which of the following cyclic structures do the ring forms of monosaccharides consist of?

A) acetals
B) hemiacetals
C) ethers
D) esters

Question 29

Which carbon atom becomes an anomeric carbon when glucose adopts a pyranose structure?

A) carbon 1
B) carbon 2
C) carbon 5
D) carbon 6

Question 30

In the cyclic structure of glucose, which carbon atoms are connected to the oxygen atom of the pyranose ring?

A) carbon 1 and carbon 5
B) carbon 1 and carbon 6
C) carbon 2 and carbon 5
D) carbon 2 and carbon 6

Question 31

Which of the following is an effect of galactosemia?

A) weight loss
B) frequent urination
C) mental retardation
D) excessive thirst

Question 32

How many chiral carbons are present in the open-chain form of a ketopentose?

A) one
B) two
C) three
D) four

Question 33

Which of the following statements is true of dextrose?

A) It is the most common aldohexose in the human body.
B) It is the sweetest naturally occurring carbohydrate.
C) It is an important constituent of membranes in the nervous system.
D) It is stored as protein when consumed in excess.

Question 34

Which of the following statements is true of levulose?

A) It is the most common aldohexose in the human body.
B) It is the sweetest naturally occurring carbohydrate.
C) It is an important constituent of membranes in the nervous system.
D) It is an important constituent of the milk sugar lactose.

Question 35

Identify a common natural source of both glucose and fructose.

A) milk
B) honey
C) eggs
D) meat

Question 36

Which of the following statements is true of galactose?

A) It is the most common aldohexose in the human body.
B) It is the sweetest naturally occurring carbohydrate.
C) It is an important constituent of membranes in the nervous system.
D) It is one of the hydrolysis products of the disaccharide sucrose.

Question 37

How many chiral carbons are present in the open-chain form of a ketohexose?

A) three
B) four
C) five
D) six

Question 38

Which of the following is associated with hyperglycemia?

A) type 2 diabetes
B) galactosemia
C) both of these
D) none of these

Question 39

Which carbon atom becomes an anomeric carbon when fructose adopts a furanose structure?

A) carbon 1
B) carbon 2
C) carbon 5
D) carbon 6

Question 40

What is the physiological role of the enzyme whose deficiency causes galactosemia?

A) It converts D-galactose to lactose.
B) It converts D-galactose to fructose.
C) It converts D-galactose to glucose.
D) It converts D-galactose to sucrose.

Question 41

Which statement is true of a solution containing an equilibrium mixture of α-D-glucose and β-D-glucose?

A) The solution has an equal amount of the two anomers.
B) The solution does not show optical activity.
C) Both of these statements are correct.
D) Neither of these statements is correct.

Question 42

Identify a membrane-bound carbohydrate that functions as a biochemical marker in animals.

A) D-idose
B) L-fucose
C) D-psicose
D) L-glucose

Question 43

In which of the following solutions can glycosides be hydrolyzed?

A) an aqueous acidic solution
B) an aqueous basic solution
C) an aqueous alcohol solution
D) all of these

Question 44

Which of the following statements is true of the α and β anomers of glucose?

A) Both the α and β anomers of glucose have the same specific rotation.
B) Both the α and β anomers of glucose have the same arrangement of -OH groups.
C) Both of these statements are correct
D) Neither of these statements is correct.

Question 45

Which carbon is the site of reaction when glucose reacts with an alcohol to form a glycoside?

A) carbon 1
B) carbon 2
C) carbon 5
D) carbon 6

Question 46

Which of the following statements is true of glucitol?

A) It exists only as an open-chain structure.
B) It exists only as a ring structure.
C) It is almost as sweet as sucrose.
D) It has a terminal aldehyde group.

Question 47

Which of the following types of reactions is involved in the formation of a glycoside from a monosaccharide?

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

Question 48

Why is mutarotation not possible in glycosides?

A) because glycosides do not have an anomeric carbon atom
B) because glycosides do not have any stereocenters that show optical activity
C) because the acetals in glycosides are not in equilibrium with the open=chain structures
D) for none of these reasons

Question 49

Which statement is true of a solution containing an equilibrium mixture of α-D-glucose and β-D-glucose?

A) The solution contains a larger percentage of the β anomer than the α anomer.
B) The solution does not show optical activity.
C) Both of these statements are correct.
D) Neither of these statements is correct.

Question 50

How are the hydroxyl groups oriented in an α-D-glucopyranose ring?

A) All the hydroxyl groups are present above the plane of the ring.
B) All the hydroxyl groups are present below the plane of the ring.
C) The hydroxyl at carbon 1 is present above the plane of the ring.
D) The hydroxyl at carbon 1 is present below the plane of the ring.

Question 51

Under which of the following conditions can monosaccharides be oxidized to aldonic acids?

A) acidic conditions
B) basic conditions
C) neutral conditions
D) all of these

Question 52

Which of the following statements is true of the α and β anomers of glucose?

A) Both the α and β anomers of glucose have a specific rotation of +112^° in an aqueous solvent.
B) The equilibrium mixture of glucose consists of 64% of the β anomer and 36% of the α anomer.
C) Both of these statements are correct.
D) Neither of these statements is correct.

Question 53

Which of the following reactions is involved in the conversion of glucose to gluconate?

A) reduction at carbon 1
B) oxidation at carbon 1
C) reduction at carbon 6
D) oxidation at carbon 6

Question 54

To which class of compounds do glycosides belong?

A) acetals
B) hemiacetals
C) ethers
D) esters

Question 55

Which of the following reactions is involved in the conversion of glucose to glucuronic acid?

A) reduction at carbon 1
B) oxidation at carbon 1
C) reduction at carbon 6
D) oxidation at carbon 6

Question 56

Which of the following reactions is involved in the conversion of glucose to glucitol?

A) reduction at carbon 1
B) oxidation at carbon 1
C) reduction at carbon 6
D) oxidation at carbon 6

Question 57

Which of the following chemical reagents react with monosaccharides to form glycosides?

A) alcohols
B) amines
C) hemiacetals
D) acetals

Question 58

How are the hydroxyl groups oriented in a β-D-glucopyranose ring?

A) All the hydroxyl groups are present above the plane of the ring.
B) All the hydroxyl groups are present below the plane of the ring.
C) The hydroxyl at carbon 1 is present above the plane of the ring.
D) The hydroxyl at carbon 1 is present below the plane of the ring.

Question 59

Which of the following statements explains the reducing nature of 2-ketoses?

A) Under acidic conditions, they exist in equilibrium with enediols that get reduced by the reducing agent.
B) Under basic conditions, they exist in equilibrium with aldoses that are oxidized by the oxidizing agent.
C) Both of these statements explain the reducing nature of 2-ketoses.
D) Neither of these statements explains the reducing nature of 2-ketoses.

Question 60

Which carbon atom becomes an anomeric carbon when ribose adopts a furanose structure?

A) carbon 1
B) carbon 2
C) carbon 5
D) carbon 6

Question 61

Which of the following disaccharides has a β-1,4-glycosidic bond?

A) lactose
B) maltose
C) sucrose
D) all of these

Question 62

Which of the following membrane-bound carbohydrates is found in the A antigens of type A blood?

A) N-acetyl-D-galactosamine
B) D-galactose
C) Both N-acetyl-D-galactosamine and D-galactose
D) Neither N-acetyl-D-galactosamine nor D-galactose

Question 63

How many monosaccharide units are present in an oligosaccharide?

A) between 3 and 5
B) between 6 and 10
C) between 11 and 15
D) between 15 and 20

Question 64

Which of the following is true of the conformations of glucose and fructose in sucrose?

A) Both fructose and glucose have α conformations.
B) Both fructose and glucose have β conformations.
C) Fructose has an α conformation, and glucose has a β conformation.
D) Fructose has a β conformation, and glucose has an α conformation.

Question 65

Which of the following disaccharides has an α, β-1,2-glycosidic bond?

A) lactose
B) maltose
C) sucrose
D) none of these

Question 66

Where is a glyosidic linkage found in a disaccharide?

A) between the anomeric carbon atom of the first unit and an -OH group of the second unit
B) between an -OH group of the first unit and the anomeric carbon atom of the second unit
C) between an -OH group of the first unit and an -OH group of the second unit
D) between the anomeric carbon atom of the first unit and the anomeric carbon atom of the second unit

Question 67

Identify a chemical reagent that is used to convert a monosaccharide to an alditol.

A) 2-methylaniline
B) sodium borohydride
C) N-acetyl-D-glucosamine
D) N-acetyl-D-galactosamine

Question 68

Approximately what percentage of plant starch is amylopectin?

A) 10-15%
B) 20-25%
C) 75-80%
D) 25-30%

Question 69

Approximately what percentage of plant starch is amylose?

A) 40-45%
B) 20-25%
C) 75-80%
D) 85-90%

Question 70

Which of the following is the sweetest carbohydrate among the given carbohydrates?

A) fructose
B) glucose
C) maltose
D) sucrose

Question 71

Which of the following statements is true of the reducing properties of sugars?

A) All monosaccharides and all disaccharides are nonreducing sugars.
B) All monosaccharides and all disaccharides are reducing sugars.
C) All disaccharides and some monosaccharides are nonreducing sugars.
D) All monosaccharides and some disaccharides are reducing sugars.

Question 72

Which of the following enzymes is used to test blood glucose levels?

A) peroxidase
B) glucose oxidase
C) glucokinase
D) glucose synthase

Question 73

Which of the following membrane-bound carbohydrates is found in the O antigens of type O blood?

A) N-acetyl-D-galactosamine
B) D-galactose
C) Both N-acetyl-D-galactosamine and D-galactose
D) Neither N-acetyl-D-galactosamine nor D-galactose

Question 74

Which of the following disaccharides has an α-1,4-glycosidic bond?

A) lactose
B) maltose
C) sucrose
D) all of these

Question 75

Under which of the following conditions can monosaccharides be oxidized to uronic acids?

A) basic conditions
B) enzymatic conditions
C) acidic conditions
D) none of these

Question 76

Which of the following statements is true of amylose?

A) It has a straight chain of as many as 4,000 D-glucose units that are linked by α-1,4-glycosidic bonds.
B) It has a straight chain of as many as 4,000 D-glucose units that are linked by β-1,4-glycosidic bonds.
C) It has a network of as many as 10,000 D-glucose units that are linked by α-1,4-glycosidic bonds.
D) It has a network of as many as 10,000 D-glucose units that are linked by β-1,4-glycosidic bonds.

Question 77

Which of the following membrane-bound carbohydrates is found in the B antigens of type B blood?

A) N-acetyl-D-galactosamine
B) D-galactose
C) Both N-acetyl-D-galactosamine and D-galactose
D) Neither N-acetyl-D-galactosamine nor D-galactose

Question 78

Which of the following statements is true of glucose 6-phosphate?

A) It is a cationic species with a charge of +1.
B) It is an electrically neutral molecule.
C) It is an anionic species with a charge of −1.
D) It is an anionic species with a charge of −2.

Question 79

Which of the following disaccharides yields two molecules of glucose on complete hydrolysis?

A) lactose
B) maltose
C) sucrose
D) none of these

Question 80

Which of the following monosaccharides is obtained by the complete hydrolysis of starch?

A) D-glucose
B) D-fructose
C) D-galactose
D) D-psicose