Deck 22: Carbohydrates

Question 1

Which is a ketohexose?

A) D-Glucose
B) D-Fructose
C) D-Mannose
D) D-Ribose
E) (+)-Sucrose

Answer 1

D-Fructose

Question 2

Which of these is a component of the mixture formed when D-galactose is placed in aqueous base (de Bruyn - van Ekenstein transformation)?

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

Answer 2

V

Question 3

Which of the following is a D-aldotetrose?

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

Answer 3

I

Question 4

A glycoside is a compound which contains the structural features of these classes of organic compounds:

A) Aldehydes and alcohols
B) Acetals and alcohols
C) Hemiacetals and alcohols
D) Ketones and alcohols
E) Alcohols and carboxylic acids

Question 5

Which of the following is an L-aldotetrose?

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

Question 6

Which reagent would cause the following conversion to take place?

A) Excess CH3OH and KOH
B) Excess CH3OH and HCl
C) Excess (CH3)2SO4 and OH-
D) Excess CH3I and H3O+
E) Excess (CH3CO)2O

Question 7

Refer to the following structures.Which aldohexose when subjected to Fischer's end-group interchange would be converted to a compound identical with itself?

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

Question 8

Which are the anomers?

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

Question 9

Which of these is α-D-glucopyranose?

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

Question 10

How many stereoisomers of the L series would exist for the following pentose? O=CHCHOHCHOHCHOHCH₂OH

A) 2
B) 3
C) 4
D) 5
E) 8

Question 11

Which of these is a glycoside?

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

Question 12

Sugars that undergo mutarotation in neutral aqueous solution are:

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

Question 13

Which would undergo mutarotation in neutral aqueous solution?

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

Question 14

Which of these reacts with dilute HCl to produce methanol?

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

Question 15

Which of the following structures represent enantiomers?

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

Question 16

Consider the structures shown below.Which structure represents $\beta$ -D-glucopyranose?

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

Question 17

Refer to the structures below.Which are L-sugars?

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

Question 18

Which reagent would be used for the following transformation?

A) CH₃I,KOH
B)

C) (CH₃)₂SO₄,NaOH
D) CH₃OH,HCl
E)

Question 19

What can be said,correctly,about a monosaccharide,the name of which is preceded only by (+)?

A) The compound is the α-anomer.
B) The compound exists in the pyranose form.
C) The compound is dextrorotatory.
D) The compound has the same stereochemistry at the penultimate carbon as D-(+)-glucose.
E) The compound exists only in open-chain form.

Question 20

What compounds (other than methanol)would be formed in the solution if glycoside presented below was treated with dilute aqueous hydrochloric acid and the solution allowed to stand?

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

Question 21

Which of the following substances will afford an optically inactive product upon reaction with nitric acid?

A) I
B) II
C) III and IV
D) II,III and IV
E) All of the above

Question 22

Which aldohexose would yield an optically active aldaric acid when treated with nitric acid?

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

Question 23

What is the ratio of products formed by the reaction of periodic acid with the following compound? H₂C=O HCO₂H
CO₂
I
5
1
0
II
3
3
0
III
1
5
0
IV
2
3
1
V
0
4
2

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

Question 24

An aldonic acid is represented by:

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

Question 25

Reaction of the following substance with bromine water would yield:

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

Question 26

Which of the following would give a positive test with Benedict's solution?

A) I
B) II
C) III
D) IV
E) All of these

Question 27

The pyranose form of an aldohexose which can react 1:2 with acetone in the presence of acid is which of these?

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

Question 28

Consider the structures below.Which monosaccharides would yield an optically active aldonic acid when oxidized with bromine water?

A) I,II,and III
B) I,II,and V
C) III,IV,and VI
D) II,III,and IV
E) All of these

Question 29

Which of the following substances will afford a meso- product upon reaction with Br₂/H₂O ?

A) I
B) II
C) III and IV
D) II,III and IV
E) None of the above

Question 30

A compound X reacts with 3 mol of HIO4 to yield 2 mol of HCO2H and 2 mol of HCHO.What is the structure of X?

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

Question 31

Which is an L-monosaccharide that would yield an optically active aldaric acid on oxidation by nitric acid?

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

Question 32

Which of these compounds,I,II,III,IV,is a reducing disaccharide?

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

Question 33

Consider the structures shown below.Which compound is not a reducing sugar?

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

Question 34

An aldaric acid is represented by:

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

Question 35

Which reagent would be used for the following transformation?

A) Ag(NH3)2+
B) HNO3
C) Br2/H2O
D) HCl
E) A and C

Question 36

Refer to the structures below.Which sugar(s)would yield an optically active aldaric acid on oxidation with nitric acid?

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

Question 37

Which of these is a non-reducing monosaccharide?

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

Question 38

Which compound will not reduce Ag(NH3)2+ ?

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

Question 39

Reaction of the following substance with nitric acid would yield:

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

Question 40

What is the ratio of products formed by the reaction of periodic acid with the following compound? H₂C=O HCO₂H
CO₂
I
5
1
0
II
3
3
0
III
1
5
0
IV
1
4
1
V
0
4
2

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

Question 41

Consider the structures above.Which monosaccharides would yield the same phenylosazone when treated with excess phenylhydrazine?

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

Question 42

Sucrose reacts with which of these reagents?

A) C₆H₅NHNH₂
B) Cu²⁺
C) Br₂/H₂O
D) H₃O⁺
E) Ag(NH₃)₂⁺

Question 43

Which reagent would be used for the following transformation?

A) CH₃OH/HCl
B) AgNO₃/C₂H₅OH
C) Br₂/CCl₄
D) KMnO₄
E) HIO₄

Question 44

Reaction of the following substance with sodium borohydride (NaBH4)would yield:

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

Question 45

Epimers are represented by:

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

Question 46

Refer to the following structures.Which D-aldohexose would react with NaBH4 to yield an optically inactive alditol?

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

Question 47

If the methyl glycoside of an aldohexose is treated with HIO4,one molar equivalent of HCHO is formed but no HCOOH.What size ring is present in the glycoside?

A) Three-membered
B) Four-membered
C) Five-membered
D) Six-membered
E) Seven-membered

Question 48

Which is not an intermediate monosaccharide in the Kiliani-Fischer synthesis of D-mannose from D-glyceraldehyde?

A) D-Ribose
B) D-Threose
C) D-Arabinose
D) D-Erythrose
E) More than one of these A and B

Question 49

A D-aldohexose,Z,is subjected to a Ruff degradation.The degradation product is treated with nitric acid to yield an optically active aldaric acid.A possible structure for Z is:

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

Question 50

Which of the following structures represent epimers?

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

Question 51

The Ruff degradation is the reaction of an aldose with:

A) Br₂/H₂O;then HCN;then H₃O⁺;then Na-Hg,H₂O
B) HCN;then Ba(OH)₂;then H₃O⁺;then Na-Hg,H₂O
C) HCN;then H₃O⁺;then Ba(OH)₂;then Na-Hg,H₂O
D) Br₂/H₂O;then H₂O₂,Fe₂(SO₄)₃
E) Br₂/H₂O

Question 52

Sugars that would yield the same phenylosazone are:

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

Question 53

Which compound is D-galactose?

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

Question 54

Consider the structures below: what term(s)describe(s)the relationship between them?

A) Enantiomers
B) Epimers
C) Diastereomers
D) Anomers
E) More than one of the above

Question 55

The Kiliani-Fisher Synthesis is the reaction of an aldose with:

A) Br₂/H₂O;then HCN;then H₃O⁺;then Na-Hg,H₂O
B) HCN;then Ba(OH)₂;then H₃O⁺;then Na-Hg,H₂O
C) HCN;then H₃O⁺;then Ba(OH)₂;then Na-Hg,H₂O
D) Br₂/H₂O;then H₂O₂,Fe₂(SO₄)₃
E) Br₂/H₂O

Question 56

Which compound or compounds would be formed when D-glucose is dissolved in methanol and then treated with anhydrous acid?

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

Question 57

Consider the structures of D-allose below: Which of the following structures represents L-allose?

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

Question 58

Refer to the structures below.Which sugars would react with phenylhydrazine to yield the same phenylosazone?

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

Question 59

A D-aldohexose X,is subjected to a Ruff degradation.The degradation product is treated with nitric acid to yield an optically inactive aldaric acid.A possible structure for X is:

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

Question 60

Which reagent would be used for the following transformation?

A) NaBH4
B) AgNO3/C2H5OH
C) Br2/CCl4
D) HCl
E) Hot KMnO4

Question 61

Which is a reducing sugar with an α-glycosidic linkage?

A) Sucrose
B) Maltose
C) Lactose
D) Cellobiose
E) None of these

Question 62

Compound X is a reducing sugar which,on hydrolysis,affords two molar equivalents of D-glucose.This hydrolysis is catalyzed by an enzyme specific for glucosides of this type: What is the identity of X?

A) Sucrose
B) Lactose
C) Maltose
D) Cellobiose
E) None of these

Question 63

Which of the following is the structure of D-galacturonic acid?

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

Question 64

Many carbohydrates exist in equilibrium with cyclic hemiacetals.Those carbohydrates that form a five-membered cyclic hemiacetal are called _____________.

Question 65

Which monosaccharide is recovered from the hydrolysis of glycogen?

A) D-Galactose
B) D-Glucose
C) D-Gulose
D) Cellobiose
E) Maltose

Question 66

The simplest carbohydrates (those that cannot be hydrolyzed to simpler carbohydrates)are called ______________.

Question 67

Consider the structures below.An L-aldohexose,X,is treated with nitric acid to yield an optically inactive aldaric acid.The same L-aldohexose,X,is subjected to a Ruff degradation and the degradation product is oxidized with nitric acid to produce an optically inactive aldaric acid.Which is a possible structure for X?

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

Question 68

Cellulose lacks nutritive value for humans because:

A) the products of its digestion are excreted without utilization.
B) its conformation prevents attack by digestive enzymes.
C) we lack the enzymes which can catalyze the hydrolysis of the glycosidic linkages.
D) it passes through the digestive tract so rapidly.
E) the molecules possess such a high molecular weight.

Question 69

A monosaccharide containing six carbon atoms and an aldehyde functionality is called an _____________.

Question 70

Carbohydrates are synthesized in green plants by _____________.

Question 71

Which of these is an example of a glucan?

A) Maltose
B) Sucrose
C) Lactose
D) Cellobiose
E) Amylose

Question 72

α-D-Glucose has [α]_D = +112^o,and β-D-glucose has [α]_D = +19^o.If either anomer is dissolved in water and allowed to reach equilibrium,the specific rotation of the solution is + 52^o.What are the percentages of each anomer at equilibrium?

Question 73

Cellulose differs from chitin in which way?

A) Cellulose has $\beta$ -glycosidic linkages;chitin has $\infty$ -glycosidic linkages.
B) Cellulose contains only D-glucose units;chitin contains only N-acetyl-D-glucosamine units.
C) Cellulose cannot be hydrolyzed;chitin can be hydrolyzed.
D) Cellulose has a linear structure;chitin has a helical structure.
E) Cellulose chains are branched;chitin chains are unbranched.

Question 74

Carbohydrates that hydrolyze to give a large number of molecules of monosaccharides are called _____________.

Question 75

The D-glucose unit at the branching point of amylopectin has free hydroxyl groups at which positions?

A) C2,C3,and C6
B) C2 and C3
C) C3 and C4
D) C3,C4,and C6
E) C4 and C6

Question 76

What is the correct description of this disaccharide?

A) The α-anomer of two D-glucose units joined by an α(1 $\rightarrow$ 4)linkage
B) The α-anomer of two D-galactose units joined by an α(1 $\rightarrow$ 4)linkage
C) The $\beta$ -anomer of two D-galactose units joined by a $\beta$ (1 $\rightarrow$ 4)linkage
D) The $\beta$ -anomer of two D-glucose units joined by a $\beta$ (1 $\rightarrow$ 4)linkage
E) The α-anomer of two D-galactose units joined by a $\beta$ (1 $\rightarrow$ 4)linkage

Question 77

An aldopentose,X,is subjected to a Kiliani-Fischer synthesis to produce two aldohexoses,Y and Z.Both Y and Z,when oxidized with nitric acid,yield optically active aldaric acids.Which structure represents X?

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

Question 78

Lactose exists in two forms α and β.Anomer α has [α]_D = +92.6^o,and anomer β has [α]_D = +34^o.What are the percentages of each anomer at equilibrium when the specific rotation of the water solution is + 52^o?

Question 79

Which of the following would yield D-glucose and D-mannose when subjected to a Kiliani-Fischer synthesis?

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

Question 80

Which monosaccharide is recovered from the hydrolysis of starch?

A) D-Galactose
B) D-Glucose
C) D-Gulose
D) Cellobiose
E) Maltose