Deck 8: Carbohydrates

Question 1

The compounds α-D-fructofuranose and β-D-fructofuranose are .

A) enantiomers
B) mutamers
C) anomers
D) conformational isomers

Answer 1

anomers

Question 2

The structures of D-ribose and D-arabinose are shown below. These two molecules are .

A) epimers
B) enantiomers
C) tautomers
D) anomers

Answer 2

epimers

Question 3

In solution α-D-glucopyranose and β-D-glucopyranose .

A) rapidly polymerize to form a heteropolymer
B) can never exist together
C) form a racemic mixture
D) form an equilibrium mixture

Answer 3

form an equilibrium mixture

Question 4

Below is the Fischer projection of D-galactose. Which is the proper Haworth projection of β-D-galactopyranose?

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

Question 5

Below is the structure for a cyclic D-monosaccharide. Which is the anomeric carbon atom?

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

Question 6

Pyranose rings are usually most stable when the ring adopts a conformation with the bulkiest ring substituents in positions.

A) chair; equatorial
B) chair; axial
C) boat; equatorial
D) boat; axial

Question 7

Examine the cyclic D-monosaccharide shown below. The ring structure is the and the linear form of this monosaccharide must be a/an .

A) α anomer; ketose
B) β anomer; ketose
C) α anomer; aldose
D) β anomer; aldose

Question 8

The functional group shown is a/an .

A) hemiacetal
B) hemiketal
C) acetal
D) ketal

Question 9

Anomers can be interconverted .

A) by rotation about carbon-carbon bonds
B) via a linear intermediate
C) by an isotopic exchange reaction
D) None of the above. Anomers cannot be interconverted.

Question 10

Which is not a glycoconjugate?

A) proteoglycan
B) glycolipid
C) glycoprotein
D) homoglycan

Question 11

Which is a product of the intramolecular cyclization of D-tagatose to form a furanose?

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

Question 12

Ribitol is a sugar alcohol that is a component of

A) vitamin C.
B) RNA.
C) FMN and FAD.
D) NAD and NADH.
E) sialic acid.

Question 13

The Fischer projections of linear D-glucose and D-galactose are shown below. These two molecules are .

A) epimers
B) enantiomers
C) anomers
D) structural constitutional) isomers

Question 14

The structure of D-arabinose is shown below. How many stereoisomers are possible for this molecule including the one shown)?

A) one
B) four
C) six
D) eight

Question 15

Examine the Fischer projection below. How is this carbohydrate classified?

A) L enantiomer; aldopentose
B) L enantiomer; ketopentose
C) D enantiomer; aldohexose
D) D enantiomer; ketopentose

Question 16

Monosaccharide derivatives in which an amino group replaces one of the hydroxyl groups may have important roles in

A) DNA structure.
B) intermediary metabolisms.
C) vitamin C.
D) sialic acids.
E) All of the above

Question 17

Which are possible conformations of a furanose molecule?

A) envelope and twist
B) chair and boat
C) cis and trans
D) A and B

Question 18

Which does not apply to dihydroxyacetone?

A) ketose
B) triose
C) chiral
D) water-soluble

Question 19

Which is true about naturally occurring monosaccharides?

A) The L-isomers predominate.
B) The D-isomers predominate.
C) The L and D-isomers occur in equal ratios.
D) The ratio of L and D-isomers varies widely depending on the source.

Question 20

The intramolecular cyclization reaction of glucose in solution .

A) generates a chiral center
B) yields a hemiacetal
C) usually forms a pyranose
D) All of the above

Question 21

Which statement is false about the sugar units in DNA?

A) They are cyclic in DNA.
B) It is a deoxy form of ribose
C) It is an epimer of glucose.
D) It has a D-configuration

Question 22

A monosaccharide whose anomeric carbon atom has a glycosidic bond to an alcohol, amine or thiol is a .

A) glycoside
B) glycoprotein
C) heteroglycan
D) glucoconjugate

Question 23

What distinguishes an aldonic acid from an alduronic acid?

A) The oxidation of the aldehyde group in an aldonic acid and the oxidation of the highest numbered carbon in the alduronic acid.
B) Aldonic acids are derivatives of aldoses, alduronic acids are derivatives of ketoses.
C) Aldonic acids are oxidized forms of linear monosaccharides; alduronic acids are oxidized forms of cyclic monosaccharides.
D) The two terms are synonyms and are used interchangeably.

Question 24

Both amylose and amylopectin molecules isolated from plant cells can contain as many as glucose residues.

A) 25
B) 500
C) 1000
D) 2000
E) 6000

Question 25

Which is a difference between maltose and cellobiose?

A) One is in cellulose and the other in starch.
B) One is linear and the other is branched.
C) The glycosidic bond is different.
D) The subunit sugars are not glucose for both.
E) All of the above

Question 26

The structure of a disaccharide is shown below. Which statement applies?

A) Both rings A and B are in equilibrium with an open chain form.
B) Only ring A is in equilibrium with an open chain form.
C) Only ring B is in equilibrium with an open chain form.
D) Neither ring is in equilibrium with an open chain form.

Question 27

Naturally occurring glycosides have roles in cells which include

A) subunits of DNA.
B) chemical signals to plants.
C) food flavoring.
D) units in cell membrane structure.
E) All of the above

Question 28

What is the name of the disaccharide shown below that is formed by joining two monomers of D-glucose?

A) β-D-glucopyranosyl-1→4)-β-D-glucopyranose
B) α-D-glucopyranosyl-1→4)-α-D-glucopyranose
C) β-D-glucofuranosyl-1→4)-β-D-glucofuranose
D) α-D-glucopyranosyl-1→3)-β-D-glucopyranose

Question 29

Enzymes in the human intestine which are needed to degrade plant starch into limit dextrin are

A) a-Amylase.
B) β-Amylase.
C) debranching enzymes.
D) A and B
E) A, B, and C

Question 30

You have two bottles, each of which contains a white, crystalline substance. Your lab director tells you that one contains lactose and the other sucrose. Your job is to determine which bottle contains which sugar. Which procedure would you use?

A) Test both for solubility in water. Sucrose is very soluble; lactose is only minimally soluble.
B) Test for the ability to reduce Ag⁺. Only lactose will react.
C) Dissolve each in water and record the pH. Lactose is far more acidic than sucrose.
D) React each with bromine Br₂) water. Only sucrose will react.

Question 31

Which is not a similarity between glycogen and amylopectin?

A) They each contain about 6000 glucose residues.
B) Each has one reducing end and many nonreducing ends.
C) Each is highly branched.
D) Each has branches of similar chain length.

Question 32

When a sugar polymer is analyzed and found to have equal portions of reducing and non-reducing ends, it is likely that

A) it shows directionality.
B) it is linear.
C) it is branched.
D) it is branched, but not very highly.
E) some of the internal glycosidic bonds are in equilibrium with open chain forms.

Question 33

Hydrolysis of maltose will yield .

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

Question 34

Amylase is a hydrolase that is an .

A) endonuclease
B) endoglycosidase
C) exonuclease
D) exoglycosidase that removes maltose
E) exoglycosidase that removes glucose monomers

Question 35

The chemical name for table sugar is and it is a .

A) lactose; monosaccharide
B) lactose; disaccharide
C) sucrose; monosaccharide
D) sucrose; disaccharide

Question 36

Polysaccharide structure can be varied by differences in

A) chain length number of sugars in each polysaccharide).
B) the kinds) of sugars in each polysaccharides.
C) the presence of branching.
D) All of the above

Question 37

What type of bond links the monomers of a polysaccharide?

A) glucotide bond
B) phosphate ester bond
C) peptide bond
D) glycosidic bond

Question 38

A reducing sugar is one that

A) contains a b1→1) link.
B) has a hemiacetal group.
C) can reduce Cu²⁺ but not Ag⁺.
D) makes you lose weight.

Question 39

The abbreviation for glucose is .

A) glu
B) gcs
C) glc
D) gluc

Question 40

Amylose differs from amylopectin in that amylose

A) has different monomers than amylopectin.
B) has more glucose residues than amylopectin.
C) is highly branched and amylopectin is not.
D) forms a helix and no branch points.

Question 41

The main reasons that glycoproteins are so diverse when compared to other proteoglycans are

A) they may contain different sugars in different combinations and chain lengths.
B) β or a-glycosidic linkages may join various carbon atoms in the sugars.
C) they are found in both bacterial, plant and animal cells.
D) A and B
E) All of the above

Question 42

The chair conformation of furanoses is generally preferred to minimize steric repulsion.

Question 43

Steric strain is a major factor in determining the conformations of a monosaccharide that predominate in solution.

Question 44

Furanoses have more three-dimensional conformations than pyranoses.

Question 45

The bacterial cell wall is sensitive to penicillin because it

A) blocks the linkage of the MurNAc and GlcNAc subunits.
B) blocks the pentaglycine bridge cross linkage.
C) binds to an enzyme which recognizes D-alanine-D-alanine dipeptide.
D) is not attacked by enzymes in animal cells.
E) All of the above

Question 46

The reaction between one molecule of alcohol and one molecule of aldehyde yields an acetal.

Question 47

The ketohexoses have fewer chiral carbon atoms than the aldohexoses.

Question 48

Highly branched cores of amlyopectin that are resistant to hydrolysis are called .

A) core saccharides
B) non-reducing saccharides
C) dextran
D) limit dextrins

Question 49

The major proteoglycan in cartilage is .

A) hyaluronic acid
B) cellobiose
C) link protein
D) aggrecan

Question 50

All carbohydrates have the empirical formula CH₂O)_n.

Question 51

The elasticity and resistance to compression of connective tissue is due to

A) the branching of the glycosaminoglycans there.
B) the glycosidic linkage to the serine of proteins in the glycosaminoglycans.
C) the carboxyl and sulfated groups in the glycosaminoglycans.
D) the rigid structure of the glycosaminoglycans.
E) All of the above

Question 52

Cellulose is not highly branched because it

A) does not have a polysaccharide backbone.
B) it does not have a-1→6) linkages.
C) it does not have β-1→4) linkages.
D) it is insoluble in water.

Question 53

Most of the carbohydrates on earth are produced by photosynthesis in plants.

Question 54

The simplest aldose is the chiral molecule glyceraldehyde.

Question 55

In solution only one anomeric form of a monosaccharide will be present.

Question 56

Chitin is

A) found in insect and crustacean shells.
B) found in fungi cell walls.
C) composed of N-acetylglucosamine subunits.
D) composed of linear fibrils like cellulose.
E) All of the above

Question 57

contain NeuNAc residues and sulfated sugars, and their negative charges contribute to the viscosity of mucins.

A) Proteoglycans
B) N-linked polysaccharides
C) O-linked polysaccharides
D) Hyaluronic acid
E) All of the above

Question 58

Nodulation factors are .

A) polysaccharides that help maintain the integrity of tree bark
B) lipo-oligosaccharides that stimulate the growth of nitrogen-fixing structures in plants
C) polysaccharides used to store energy in the roots of plants
D) lipo-saccharides that are often found in tumors

Question 59

Vitamin C is an enediol of a lactone and is vital in the synthesis of collagen.

Question 60

All D-enantiomers of carbohydrates are dextrorotatory.

Question 61

Unlike proteins, whose primary structures are encoded in DNA, polysaccharides have very little structural variations.

Question 62

a-amylases hydrolyze (a-1→4) linkages and β-amylases hydrolyze (β-1→4) linkages, but neither attack (a-1→6) linkages.

Question 63

An oligosaccharide nodulation factor from one species can stimulate symbiosis in another species.

Question 64

The heteroglycan component of the cell wall is the same in all bacteria, but the cross-linking polypeptide is not.

Question 65

The sugar derivative found in DNA is an oxidized form of ribose.

Question 66

Heteroglycan chains may or may not be covalently bound to proteins in proteoglycans.

Question 67

The large number of possible oligosaccharide structures in glycoproteins is limited in cells by the kinds of enzymes available for their synthesis.

Question 68

Cellulose cannot be degraded in cattle.

Question 69

Enzymatic lengthening and degradation of glycogen occurs only at the non-reducing ends.

Question 70

For cattle, cellulose is a storage homoglycan.

Question 71

Homoglycans are used for storage, while heteroglycans are used for cell structure.

Question 72

The main difference between structures of amylopectin and glycogen is the specific sugar subunit.

Question 73

Some glycoproteins may have identical protein components and variable polysaccharide components.

Question 74

DNA could be referred to as a glycoside.

Question 75

Sugar alcohols do not have a carbonyl group.

Question 76

Both nucleotides and nucleosides are glycosides.

Question 77

Enzymes that hydrolyze cellulose cannot hydrolyze amylopectin.