Deck 20: Carbohydrates

Question 1

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

A)
B)
C)
D)

Answer 1

A

Question 2

Including pairs of enantiomers, how many different aldohexoses are there?

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

Answer 2

D

Question 3

Carbohydrates account for approximately what percentage of the body weight of animals?

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

Answer 3

A

Question 4

How many different D-2-ketopentoses are there?

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

Question 5

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

A) Carbohydrates cannot be hydrolyzed.
B) Hydrolysis of carbohydrates can only yield polyhydroxyaldehydes.
C) Hydrolysis of carbohydrates can only yield polyhydroxyketones.
D) Hydrolysis of carbohydrates can yield polyhydroxyaldehydes and/or polyhydroxyketones.

Question 6

How many different D-aldopentoses are there?

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

Question 7

Including pairs of enantiomers, how many different trioses are there?

A) 1
B) 2
C) 3
D) 4

Question 8

Including pairs of enantiomers, how many different aldopentoses are there?

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

Question 9

How many different D-2-ketohexoses are there?

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

Question 10

The configuration at which carbon of a tetrose determines if the tetrose has the D or L configuration?

A) C-1
B) C-2
C) C-3
D) C-4

Question 11

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

A) 3
B) 4
C) 5
D) 6

Question 12

Including pairs of enantiomers, how many different 2-ketopentoses are there?

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

Question 13

Which of the following carbohydrates is associated with crustacean shells?

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

Question 14

The configuration at which carbon of a pentose determines if the pentose has the D or L configuration?

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

Question 15

Carbohydrates account for approximately what percentage of the dry weight of plants?

A) 10%
B) 25%
C) 50%
D) 75%

Question 16

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

A)
B)
C)
D)

Question 17

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

A) 2
B) 3
C) 4
D) 5

Question 18

How many different D-aldohexoses are there?

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

Question 19

Which are the most abundant organic compounds in the plant world?

A) alcohols
B) amino acids
C) carbohydrates
D) proteins

Question 20

Including pairs of enantiomers, how many different 2-ketohexoses are there?

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

Question 21

How many amino sugars are common in nature?

A) 1
B) 2
C) 3
D) 4

Question 22

The cyclic structures of monosaccharides are which of the following?

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

Question 23

Which of the following is a generally mild disease?

A) galactosemia
B) galactosuria
C) both a and b
D) neither a nor b

Question 24

For the solvents water, ethanol, and benzene which gives the correct order of solubility of monosaccharides?

A) benzene > ethanol > water
B) benzene > water > ethanol
C) water > ethanol > benzene
D) water > benzene > ethanol

Question 25

The sugars in RNA and DNA are ribose and deoxyribose respectively. Which of the following describes the relationship between these two sugars?

A) In deoxyribose the oxygen lost is from the hydroxyl on C-1 of ribose.
B) In deoxyribose the oxygen lost is from the hydroxyl on C-2 of ribose.
C) In deoxyribose the oxygen lost is from the hydroxyl on C-3 of ribose.
D) In deoxyribose the oxygen lost is from the hydroxyl on C-4 of ribose.

Question 26

The D-form of which of the following amino sugars is not commonly found naturally?

A) galactosamine
B) glucosamine
C) mannosamine
D) ribosamine

Question 27

Which of the following functional groups is present in N-acetylglucosamine?

A) amide
B) 1° amine
C) 2° amine
D) 3° amine

Question 28

When an aldohexose such as glucose adopts the pyranose structure which atoms are connected by an oxygen atom?

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

Question 29

Which of the following occurs when a monosaccharide is converted to an amino sugar?

A) An amino group replaces an aldehyde carbonyl.
B) An amino group replaces a ketone carbonyl.
C) An amino group replaces a hydroxyl group.
D) Any of the above, it depends on the identity of the monosaccharide.

Question 30

When fructose adopts a furanose structure which carbon is the anomeric carbon?

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

Question 31

When glucose adopts a pyranose structure which carbon is the anomeric carbon?

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

Question 32

Which of the following is a severe disease?

A) galactosemia
B) galactosuria
C) both a and b
D) neither a nor b

Question 33

What is the relationship between the number of stereocenters in a monosaccharide in its open-chain and ring structures?

A) The two structures contain the same number of stereocenters.
B) The open-chain form contains one less stereocenter than does the ring.
C) The open-chain form contains one more stereocenter than does the ring.
D) There is no general relationship, each case must be considered separately.

Question 34

To which carbon of a monosaccharide is the amino group bound in the amino sugars commonly found in nature?

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

Question 35

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

A) 1
B) 2
C) 3
D) 4

Question 36

Approximately how many infants are born with galactosemia?

A) 1 in 1.8 × 10²
B) 1 in 1.8 × 10⁴
C) 1 in 1.8 × 10³
D) 1 in 1.8 × 10⁵

Question 37

When a ketohexose such as fructose adopts the furanose structure which atoms are connected by an oxygen atom?

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

Question 38

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

A) 3
B) 4
C) 5
D) 6

Question 39

The D-form of which of the following amino sugars is commonly found naturally?

A) allosamine
B) althrosamine
C) mannosamine
D) none of these

Question 40

Which of the following is associated with the projections commonly used to illustrate furanoses and pyranoses?

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

Question 41

Which of the following is true of glucitol?

A) It exists only as an open-chain structure.
B) It exists only as a ring structure.
C) It exists as both ring and open-chain structures with the open-chain structure predominating.
D) It exists as both ring and open-chain structures with the ring structure predominating.

Question 42

Which carbon is the site of reaction when glucose reacts to form a glucoside?

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

Question 43

Which sugar is the starting material used by plants to synthesize vitamin C?

A) D-fructose
B) L-fructose
C) D-glucose
D) L-glucose

Question 44

What reaction occurs when glucose is converted to gluconate?

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

Question 45

Which of the following explains why glycosides do not undergo mutarotation?

A) There is no longer an anomeric carbon.
B) There are no longer any stereocenters.
C) The ring structure does not open to become the open-chain structure.
D) None of the above is correct.

Question 46

Which of the following is true of the spatial distribution of the hydroxyl groups of α-D-glucopyranose?

A) They are all in axial positions.
B) They are all in equatorial positions.
C) The hydroxyl on C-1 is axial, those on C-2, C-3 and C-4 are equatorial.
D) The hydroxyl on C-1 is equatorial, those on C-2, C-3 and C-4 are axial.

Question 47

The formation of a glycoside from a sugar is which of the following reactions?

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

Question 48

What reaction occurs when glucose is converted to glucuronic acid?

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

Question 49

Which of the following explains why ketoses are reducing sugars?

A) Under acidic conditions they are converted to aldoses.
B) Under basic conditions they are converted to aldoses.
C) both a and b
D) neither a nor b

Question 50

Which of the following is true of the spatial distribution of the hydroxyl groups of β-D-glucopyranose?

A) They are all in axial positions.
B) They are all in equatorial positions.
C) The hydroxyl on C-1 is axial, those on C-2, C-3 and C-4 are equatorial.
D) The hydroxyl on C-1 is equatorial, those on C-2, C-3 and C-4 are axial.

Question 51

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

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

Question 52

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

A) They have equal but opposite optical rotations.
B) They are equally stable.
C) both a and b
D) neither a nor b

Question 53

Which of the following reagents is capable of hydrolyzing glycosides?

A) acids
B) bases
C) water
D) all of these

Question 54

Which of following describes a solution in which the α and β anomers of glucose have reached equilibrium?

A) There are equal amounts of the two anomers.
B) The solution shows no optical activity.
C) both a and b
D) neither a nor b

Question 55

What reaction occurs when glucose is converted to glucitol?

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

Question 56

Which of the following reacts with sugars to form glycosides?

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

Question 57

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

A) They both rotate light to the right (i.e. +), but not to the same extent.
B) They are equally stable.
C) both a and b
D) neither a nor b

Question 58

Which of following describes a solution in which the α and β anomers of glucose have reached equilibrium?

A) There is more β anomer present than α anomer.
B) The solution shows no optical activity.
C) both a and b
D) neither a nor b

Question 59

When ribose adopts a furanose structure which carbon is the anomeric carbon?

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

Question 60

Glycosides are examples of which class of compounds?

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

Question 61

The reaction of monosaccharides to form a disaccharide is an example of which of the following reactions?

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

Question 62

What is the charge on glucose 6-phosphate?

A) 0
B) −1
C) −2
D) −3

Question 63

Which of the following determines blood type O in the ABO blood typing system?

A) the presence of only N-acetyl-D-galactosamine antigen
B) the presence of only N-acetyl-D-galactose antigen
C) the presence of both N-acetyl-D-galactosamine and N-acetyl-D-galactose antigens
D) the absence of both N-acetyl-D-galactosamine and N-acetyl-D-galactose antigens

Question 64

Which of the following 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 65

Which of the following is the sweetest?

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

Question 66

In sucrose, which of the following describes the glycosidic bond between C-1 of glucose and C-2 of fructose?

A) for both fructose and glucose it is α
B) for both fructose and glucose it is β
C) for fructose it is α and for glucose it is β
D) for fructose it is β and for glucose it is α

Question 67

Complete hydrolysis of which of the following disaccharides yields a single monosaccharide?

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

Question 68

In the test for blood glucose which of the following is formed?

A) D-glucitol
B) D-gluconic acid
C) D-glucuronic acid
D) methyl-α-D-glucopyranoside

Question 69

An α(1 → 2) glycosidic bond is found in which of the following?

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

Question 70

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

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

Question 71

Which of the following is true about 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

A β(1 → 4) glycosidic bond is found in which of the following?

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

Question 73

An α(1 → 4) glycosidic bond is found in which of the following?

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

Question 74

Which of the following determines blood type A in the ABO blood typing system?

A) the presence of only N-acetyl-D-galactosamine antigen
B) the presence of only D-galactose antigen
C) the presence of both N-acetyl-D-galactosamine and D-galactose antigens
D) the absence of both N-acetyl-D-galactosamine and D-galactose antigens

Question 75

Which of the following is obtained as a result of the complete hydrolysis of starch?

A) D-glucose
B) lactose
C) maltose
D) sucrose

Question 76

Approximately what percentage of plant starch is amylopectin?

A) 10 to 15%
B) 20 to 25%
C) 75 to 80%
D) 85 to 90%

Question 77

Approximately what percentage of plant starch is amylose?

A) 10 to 15%
B) 20 to 25%
C) 75 to 80%
D) 85 to 90%

Question 78

How many monosaccharide units are in molecules called oligosaccharides?

A) 3 to 6
B) 6 to 10
C) 10 to 15
D) 15 to 20

Question 79

Which of the following determines blood type B in the ABO blood typing system?

A) the presence of only N-acetyl-D-galactosamine antigen
B) the presence of only D-galactose antigen
C) the presence of both N-acetyl-D-galactosamine and D-galactose antigens
D) the absence of both N-acetyl-D-galactosamine and D-galactose antigens

Question 80

Which of the following is true of amylose?

A) It consists of as many as 4000 D-glucose units linearly linked by α(1 → 4) glycosidic bonds.
B) It consists of as many as 4000 D-glucose units linearly linked by β(1 → 4) glycosidic bonds.
C) It consists of as many as 10,000 D-glucose units linearly linked by α(1 → 4) glycosidic bonds and there are branches every 24-30 units via α(1 → 6) glycosidic bonds.
D) It consists of as many as 10,000 D-glucose units linearly linked by β(1 → 4) glycosidic bonds and there are branches every 24-30 units via β(1 → 6) glycosidic bonds.