Deck 16: Carbohydrates

Question 1

Sugars which differ in chirality only around one carbon are most specifically called

A) anomers.
B) diastereoisomers.
C) enantiomers.
D) epimers.
E) none of these

Answer 1

D

Question 2

Which of the following monosaccharides is a ketose?

A) glucose
B) fructose
C) galactose
D) mannose

Answer 2

B

Question 3

Exhibit 16B
A carbohydrate Fischer projection.
Refer to Exhibit 16B.Which of the following figures represents the Haworth projection of the carbohydrate shown?

A)
B)
C)
D)

Answer 3

A

Question 4

Aldoses can form which type of cyclic structure?

A) Hemiacetal
B) Hemiketal
C) Both hemiacetal and hemiketal
D) Neither hemiacetal and hemiketal

Question 5

The simplest aldotriose is:

A) acetone
B) dihydroxyacetone
C) glyceraldehyde
D) threose

Question 6

Exhibit 16B A carbohydrate Fischer projection.
Refer to Exhibit 16B.The carbohydrate shown is

A) the D isomer.
B) the L isomer.
C) both D and L.
D) neither D nor L.
E) It's impossible to tell from a picture which isomer this is.

Question 7

In a Fischer projection,which chiral carbon determines whether the sugar is the D- or the L-isomer?

A) highest numbered carbon atom
B) lowest numbered asymmetric carbon atom
C) lowest numbered carbon atom
D) highest numbered asymmetric carbon atom

Question 8

For the a anomer of a D-sugar,the anomeric hydroxyl in a Haworth projection

A) has an upward projection (on the same side as the terminal CH₂OH group).
B) has a downward projection (on the opposite side from the terminal CH₂OH group).
C) may be either up or down, it depends on the individual sugar.
D) is non-existent; anomers are a consideration only in Fischer projections.

Question 9

Epimers are

A) stereoisomers that differ from each other in their configuration at two or more carbon atoms.
B) stereoisomers that differ from each other in their configuration at a single carbon atom.
C) the a and b forms of cyclic sugars.
D) two related compounds, pyran and furan.

Question 10

How many enantiomeric pairs are possible for a aldohexose?

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

Question 11

The cyclic form of sugars

A) has one more chiral center (the anomeric carbon) than the open-chain form.
B) loses a chiral center compared to the open-chain form.
C) is not usually found in nature.
D) has one more carbon atom than the open-chain form.
E) has one less carbon atom than the open-chain form.

Question 12

Diastereomers are

A) mirror-image, nonsuperimposable stereoisomers.
B) non-mirror-image, nonsuperimposable stereoisomers.
C) stereoisomers with one or more double bonds.
D) none of the above.

Question 13

Exhibit 16A Refer to Exhibit 16A.The enantiomer of D-glucose is:

A) D-Fructose
B) D-Glucose
C) L-Glucose
D) L-Idose
E) D-Galactose

Question 14

See figure 16.4 in the textbook.D-erythrose is to D-ribose as D-ribose is to:

A) D-allose
B) D-altrose
C) D-glucose
D) D-galactose

Question 15

Haworth projection formulas

A) are representations of the cyclic form of sugars
B) can show the distinction between the a and b anomers
C) both of the above
D) neither of the above

Question 16

Which of the following is not a function of carbohydrates?

A) They are major energy sources.
B) They play key roles in processes that take place on the surface of cells.
C) They are used in structural roles.
D) They are catalytic components of enzymes.

Question 17

Exhibit 16B A carbohydrate Fischer projection.
Refer to Exhibit 16B.The carbohydrate shown is

A) a monosaccharide
B) a ketose.
C) a hexose.
D) all of these
E) none of these

Question 18

The simplest ketotriose is

A) glyceraldehyde.
B) dihydroxyacetone.
C) ribose.
D) glucose.
E) sucrose.

Question 19

Mirror image stereoisomers are called

A) anomers.
B) diastereoisomers.
C) enantiomers.
D) epimers.

Question 20

How many carbon atoms are in the simplest carbohydrates?

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

Question 21

Two samples containing identical mixtures of sugars are analyzed,one using Tollen's reagent,the other with glucose oxidase.Which will give a stronger reaction?

A) Tollen's reagent
B) glucose oxidase
C) They will have identical strengths.
D) It's impossible to predict from the information provided.

Question 22

Which of the following is true concerning the molecule pictured?

A) It would give a positive reaction in a Tollen's silver mirror test
B) It is a reducing sugar
C) It is not a reducing sugar because it is an aldose
D) It is not a reducing sugar because the anomeric hydroxyl is methlyated

Question 23

Which of the following groups is produced when an aldehyde is oxidized?

A) ketone
B) carboxyl
C) alcohol
D) ether

Question 24

Isomers of sugars in which the position of ketone and aldehyde groups have been changed are called

A) anomers.
B) diastereoisomers.
C) enantiomers.
D) epimers.
E) none of these

Question 25

When monosaccharides are bonded together

A) one H₂O molecule is lost for each new link formed.
B) oligosaccharides are formed by combining a few monosaccharides.
C) polysaccharides are formed by combining many monosaccharides.
D) all of these

Question 26

Deoxyribose is best described as a(n):

A) oxidized form of ribose
B) reduced pyranose
C) polyhydroxyl alcohol
D) glycoside
E) reduced form of a pentose

Question 27

Which of the following statements concerning sugar polymers is false?

A) Branched polymers have one non-reducing end and many reducing ends.
B) Linear polymers are more water-soluble than branched ones.
C) Branched polymers are more water-soluble than linear ones.
D) Sugar polymers may vary both in the composition of the sugar monomers and in the types of connecting glycosidic bonds.

Question 28

Which of the following compounds is produced by oxidation of an aldose in the cyclic form?

A) a hemiacetal
B) a hemiketal
C) a lactone
D) an amino sugar

Question 29

Glycosidic bonds from sugars

A) always link to the other molecule through an oxygen atom.
B) always link to the other molecule through a nitrogen atom.
C) may link to the other molecule through either an oxygen or a nitrogen atom

Question 30

Which of the following best describes the glycosidic bond in the disaccharide shown?

A) a(1-4)
B) b(1-4)
C) a(2-4)
D) b(2-4)
E) None of the above.

Question 31

A furanose is a sugar that

A) contains a five-membered ring as part of its cyclic structure.
B) contains a six-membered ring as part of its cyclic structure.
C) is a five-carbon open-chain sugar.
D) is a six-carbon open-chain sugar.

Question 32

Exhibit 16A Refer to Exhibit 16A.Epimers of D-Glucose include:

A) D-Fructose and L-Glucose
B) D-Glucose and L-Glucose
C) L-Glucose and L-Idose
D) L-Idose and D-Galactose
E) L-Glucose and D-Galactose

Question 33

A pyranose is a sugar that

A) contains a five-membered ring as part of its cyclic structure.
B) contains a six-membered ring as part of its cyclic structure.
C) is a five-carbon open-chain sugar.
D) is a six-carbon open-chain sugar.

Question 34

A lactone is a cyclic

A) ether.
B) ester.
C) ketone.
D) alcohol.

Question 35

Which carbon of the open-chain form of a sugar becomes the anomeric carbon in the cyclic form?

A) the carbonyl carbon
B) the highest numbered chiral center
C) the highest numbered carbon
D) It depends on the individual sugar.

Question 36

Exhibit 16A Refer to Exhibit 16A.Diastereoisomers of D-Glucose include all of these,except:

A) D-Fructose
B) L-Glucose
C) L-Idose
D) D-Galactose
E) All of these are diastereoisomers of D-Glucose.

Question 37

The a and b forms of the same sugar are called

A) anomers.
B) diastereoisomers.
C) enantiomers.
D) epimers.
E) none of these

Question 38

For a D-sugar,any group that is written to the right of the carbon in a Fischer projection

A) has an upward projection in a Haworth projection.
B) has a downward projection in a Haworth projection.
C) may be either up or down in a Haworth projection, it depends on the individual sugar.
D) is missing from a Haworth projection.

Question 39

Glycosidic linkages between monosaccharide units may vary based on

A) the anomeric form of the cyclic structure, i.e., a or b.
B) which -OH group is involved.
C) both of these
D) none of these

Question 40

The conversion of a sugar's carbonyl to an alcohol is

A) a reduction reaction.
B) an oxidation reaction.
C) a glycosidic reaction.
D) impossible.

Question 41

The following sugar is also called fruit sugar:

A) Fructose
B) Glucose
C) Lactose
D) Sucrose
E) Maltose

Question 42

Cellulose is indigestible to most animals because

A) animals do not have the enzymes needed to hydrolyze ester linkages between the monomer units
B) animals do not have the enzymes needed to hydrolyze the a-glycosidic linkages between the monomer units
C) animals do not have the enzymes needed to hydrolyze the b-glycosidic linkages between the monomer units
D) its molecular weight is too high for it to be degraded by enzymes

Question 43

Lactose intolerance

A) arises from inability to metabolize the disaccharide lactose
B) depends on a deficiency of sucrose in the diet
C) is based on the composition of lactose, consisting glucose and fructose in glycosidic linkage
D) arises because lactose is a dimer of galactose

Question 44

Lactose is composed of the following simple sugars:

A) galactose only
B) glucose only
C) fructose only
D) galactose and glucose
E) glucose and fructose
F) galactose and fructose

Question 45

Humans are not able to digest cellulose as a food source because:

A) Cellulose is very insoluble.
B) It is more important that the cellulose is used as fiber in our bodies.
C) We lack the enzyme to break the b linkage in the cellulose.
D) Cellulose is insoluble and we lack the enzyme to break the b linkage in the cellulose.
E) All of these are reasons why we cannot digest cellulose.

Question 46

Which of the following molecules is a disaccharide?

A) glucose
B) lactose
C) fructose
D) galactose

Question 47

The difference between cellobiose and maltose is:

A) one contains glucose and the other fructose
B) they contain different monosaccharides
C) they both contain glucose units but are connected together at different carbons
D) one has an á linkage and the other a â linkage
E) there is no difference between the two

Question 48

In bacterial cell walls

A) polysaccharides form nonspecific mixtures with proteins
B) polysaccharides are hydrogen bonded together
C) peptides form crosslinks between polysaccharides
D) oligosaccharides form crosslinks between proteins

Question 49

Which of the following is not a reducing sugar?

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

Question 50

Sucrose is composed of the following simple sugars:

A) galactose only
B) glucose only
C) fructose only
D) galactose and glucose
E) glucose and fructose
F) galactose and fructose

Question 51

Common table sugar is

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

Question 52

Which of the following statements associated with cellulose is false?

A) It's a linear polymer of glucose.
B) The glycosidic linkage is b(1 4).
C) Hydrolysis is accomplished enzymatically by cellulase.
D) Most animals can easily digest this compound.

Question 53

Which of the following molecules have the highest degree of a[1-6] branching linkages

A) Amylose
B) Amylopectin
C) Starch
D) Glycogen
E) All of these have the same degree of branching

Question 54

Exhibit 16C A polysaccharide.
Refer to Exhibit 16C.Which lettered subunit is the reducing end?

A) A
B) B
C) C
D) There is more than one nonreducing end on this carbohydrate.
E) There are no nonreducing ends on this carbohydrate.

Question 55

Which of the following disaccharides cannot be digested by mammals?

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

Question 56

Maltose is composed of the following simple sugars:

A) galactose only
B) glucose only
C) fructose only
D) galactose and glucose
E) glucose and fructose
F) galactose and fructose

Question 57

The following sugar is also called blood sugar:

A) Fructose
B) Glucose
C) Lactose
D) Sucrose
E) Maltose

Question 58

Exhibit 16C A polysaccharide.
Refer to Exhibit 16C.Which lettered subunit is the nonreducing end?

A) A
B) B
C) C
D) There is more than one nonreducing end on this carbohydrate.
E) There are no nonreducing ends on this carbohydrate.

Question 59

Which of the following artificial sweeteners is a chemical derivative of sucrose?

A) saccharin
B) cyclamates
C) sucralose
D) aspartame

Question 60

The following sugar is also called milk sugar:

A) Fructose
B) Glucose
C) Lactose
D) Sucrose
E) Maltose

Question 61

A major difference between amylose and amylopectin is that

A) amylose is connected by a(1-4) bonds and amylopectin is connected by b(1-4) bonds.
B) amylose is branched and amylopectin is not.
C) amylopectin is branched and amylose is not.
D) each is composed different types of sugar residues.

Question 62

The blue color in a well-known test for the presence of starches is due to

A) the formation of crosslinks between molecules of starch, caused by the addition of Cu²⁺
B) the reaction of the silver-ammonia complex ion with the hydroxyl groups of the starch
C) the formation of a complex between iodine and amylose
D) none of these

Question 63

The most common biopolymer on earth is this carbohydrate:

A) Glucose
B) Cellulose
C) Starch
D) Chitin
E) None of these carbohydrates is very common.

Question 64

Insoluble fiber in the diet is better at binding toxic substances than soluble fiber.

Question 65

Amino or acid derivatives of sugars are very important in which of the following biological functions?

A) Structural roles
B) Lubricating fluids
C) Cell surface sugars used in cell identity
D) Both structural roles and lubricating fluids.
E) All of the above are functions of amino and acid sugar derivatives.

Question 66

Cell walls

A) occur in plants, animals, and bacteria
B) are found in plants and bacteria, but have different chemical compositions
C) have the same chemical composition in plants and bacteria
D) have the same chemical composition in plants and animals

Question 67

Polysaccharides used in cell wall structure contribute rigidity to the wall due to covalent cross-linking between the fibers.

Question 68

Glycogen is sometimes called animal starch

Question 69

Glycogen has a similar structure to amylopectin,but is less highly branched.

Question 70

Plant starch includes amylopectin and cellulose

Question 71

There are two forms of starch:

A) amylose and glycogen, both of which are highly branched polysaccharides
B) glycogen and chitin, both of which are linear polysaccharides
C) amylopectin and glycogen, both of which are linear polysaccharides
D) amylose, which is a linear polysaccharide, and amylopectin, which is highly branched

Question 72

Glycogen breakdown proceeds from the nonreducing ends.

Question 73

A bacterial cell wall is composed of:

A) A polysaccharide consisting of a single type of monosaccharide unit and cross-linking oligopeptides.
B) A polysaccharide consisting of 2 types of monosaccharide units and cross-linking oligopeptides.
C) A polysaccharide consisting of 3 types of monosaccharide units and cross-linking oligopeptides.
D) Two different polysaccharides and 1 type of oligopeptide, which are cross-linked.

Question 74

Exhibit 16C A polysaccharide.
Refer to Exhibit 16C.Which best describes the polysaccharide?

A) homopolysaccharide
B) heteropolysaccharide
C) aminopolysaccharide
D) cryptopolysaccharide

Question 75

Glycogen is

A) polysaccharide storage polymer found in plants
B) a linear polysaccharide
C) a highly branched polysaccharide found in animals
D) a synthetic sugar substitute

Question 76

Exhibit 16C A polysaccharide.
Refer to Exhibit 16C.Which best describes bond #3?

A) a[1,3]
B) b[1,3]
C) a[2,4]
D) b[2,4]
E) None of the above is a proper description.

Question 77

Insoluble fiber in the diet is better at better at providing bulk and stimulating peristaltic action than soluble fiber.

Question 78

One major difference between bacterial and plant cell walls is that bacterial cell walls have polysaccharides that are crosslinked by peptides.

Question 79

Which of the following has only a[1-4] linkages and no a[1-6] linkages

A) Glycogen
B) Amylose
C) Amylopectin
D) Starch
E) Cellobiose

Question 80

The linkage between the glucose residues in amylopectin and glycogen is:

A) For the main chain a (1 4) and b (1 4) for the branches
B) For the main chain a (1 6) and a (1 4) for the branches
C) For the main chain a (1 4) and a (1 6) for the branches
D) For the main chain b (1 4) and b (1 6) for the branches
E) The linkage between the glucose residues is variable.