Deck 26: Carbohydrates

Question 1

Which is the correct Fischer projection for the open-chain form of the carbohydrate shown below?

A)A
B)B
C)C
D)D

Answer 1

C

Question 2

Is the following carbohydrate D or L? Provide an explanation for your answer.

A)It is D because the OH group on C2 is on the right.
B)It is L because the OH group on C4 is on the left.
C)It is L because the OH group on C3 is on the left.
D)It is D because the sugar is not symmetric.

Answer 2

It is L because the OH group on C4 is on the left.

Question 3

What are the products of the following reaction?

A)A
B)B
C)C
D)D

Answer 3

D

Question 4

How many carbons does a pentose sugar have?

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

Question 5

Which of the following reagents would convert glucose into ethyl glucopyranoside?

A)EtBr,aq.HCl
B)EtOH,aq.HCl
C)EtOH,NaOH
D)Ag₂O in NH₄OH

Question 6

Does a monosaccharide prefer to exist in the open-chain or closed-ring form?

A)Open
B)Closed
C)Both forms exist in equal ratios.

Question 7

What is the process called for the interconversion of one anomer to the other?

A)Racemization
B)Mutarotation
C)Epimerization
D)Enolization

Question 8

How many possible stereoisomers are there of the following heptose?

A)16
B)21
C)32
D)64

Question 9

What is the correct chair form for the aanomer of D-mannose?

A)A
B)B
C)C
D)D

Question 10

Which of the following reagents will selectively oxidize an aldose to an aldonic acid?

A)PCC
B)Ag₂O in NH₄OH
C)FeCl₃
D)HNO₃

Question 11

Which of the following is a reducing sugar?

A)A
B)B
C)C
D)D

Question 12

Which of the following pairs of carbohydrates will afford the same product from a Wohl degradation?

A)Xylose/glucose
B)Ribose/arabinose
C)Fructose/mannose
D)Lyxose/threose

Question 13

Which is the correct Haworth projection for the aanomer of allose?

A)A
B)B
C)C
D)D

Question 14

What is the correct chair form for the banomer of D-glucose?

A)A
B)B
C)C
D)D

Question 15

Cellulose is a polysaccharide with ________ linkages.

A)b-1,4'-glycosidic
B)a-1,4'-glycosidic
C)b-1,6'-glycosidic
D)a-1,6'-glycosidic

Question 16

Amylose is a polysaccharide with ________ linkages.

A)b-1,4'-glycosidic
B)a-1,4'-glycosidic
C)b-1,6'-glycosidic
D)a-1,6'-glycosidic

Question 17

Which of the following compounds is an aldose?

A)A
B)B
C)C
D)D

Question 18

Which of the following compounds is not a valid representation for D-glucose?

A)A
B)B
C)C
D)D
E)E

Question 19

Which is the correct Haworth projection for the banomer of D-glucose?

A)A
B)B
C)C
D)D

Question 20

Which of the following compounds is a b anomer?

A)A
B)B
C)C
D)D

Question 21

What is the best description of the product formed in the following reaction sequence?

A)The product is an optically active aldonic acid.
B)The product is an optically inactive aldonic acid.
C)The product is an optically active aldaric acid.
D)The product is an optically inactive aldaric acid.

Question 22

Upon hydrolysis of amylose,what sugar is formed?

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

Question 23

What is the composition of lactose?

A)Two glucose units with a a-1,4'-glycoside bond
B)One glucose and one fructose unit with a a-glycosidic bond to the 2' carbon of a fructofuranose ring
C)One galactose and one glucose unit with a b-1,4'-glycoside bond
D)Repeating unit of glucose units joined in a b-1,4'-glycosidic linkage

Question 24

Oxidation of a D-hexose with nitric acid forms an optically active aldaric acid.A Wohl degradation of the same D-hexose followed by oxidation with nitric acid forms an optically active aldaric acid.What are the three possible D-hexoses that fit this data?

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

Question 25

Upon hydrolysis of cellulose,what sugar is formed?

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

Question 26

Which of the following sugars can be classified as an aldohexose?

A)A
B)B
C)C
D)D

Question 27

The following reaction is an example of a base-catalyzed epimerization reaction in which a ketose is converted to a pair of aldoses.What are the products from this reaction?

A)D-glucose and D-mannose
B)D-galactose and D-talose
C)D-talose and D-idose
D)D-glucose and D-idose

Question 28

Which of the following best describes the relationship between D-glucose and D-fructose?

A)Enantiomers
B)Epimers
C)Anomers
D)Constitutional isomers

Question 29

What is the composition of maltose?

A)Two glucose units with a a-1,4'-glycoside bond
B)One glucose and one fructose unit with a a-glycosidic bond to the 2' carbon of a fructofuranose ring
C)One galactose and one glucose unit with a b-1,4'-glycoside bond
D)Repeating unit of glucose units joined in a b-1,4'-glycosidic linkage

Question 30

Which of the following sugars can be classified as a ketotetrose?

A)A
B)B
C)C
D)D

Question 31

Which of the following sugars can be classified as a ketopentose?

A)A
B)B
C)C
D)D

Question 32

Which sugar is represented by the line angle structure below?

A)D-fructose
B)D-sorbose
C)L-psicose
D)L-tagatose

Question 33

From the disaccharides listed below,which one will not undergo mutarotation?

A)Sucrose
B)Maltose
C)Lactose
D)Xylobiose

Question 34

Upon hydrolysis of amylopectin,what sugar is formed?

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

Question 35

Which of the following sugars can be classified as a ketohexose?

A)A
B)B
C)C
D)D

Question 36

From the sugars shown below,which one is a non-reducing sugar?

A)A
B)B
C)C
D)D

Question 37

What is the composition of sucrose?

A)Two glucose units with a a-1,4'-glycoside bond
B)One glucose and one fructose unit with a a-glycosidic bond to the 2' carbon of a fructofuranose ring
C)One galactose and one glucose unit with a b-1,4'-glycoside bond
D)Repeating unit of glucose units joined in a b-1,4'-glycosidic linkage

Question 38

From the sugars shown below,which one will not give a positive test with Tollens reagent?

A)A
B)B
C)C
D)D

Question 39

After a series of Kiliani-Fischer syntheses on D-glyceraldehyde,an unknown sugar was isolated from the reaction mixture.The following experimental data was obtained.What is the structure of this unknown sugar? Data:
- Molecular formula: C₆H₁₂O₆
- Reacts with phenylhydrazine to give an osazone,mp 178°C.
- Reacts with HNO₃ to give an optically active aldaric acid.
- Wohl degradation followed by HNO₃ oxidation gives an optically inactive
Aldaric acid.
- Two Wohl degradations followed by HNO₃ oxidation give a meso-tartaric acid.

A)A
B)B
C)C
D)D

Question 40

The branching units in amylopectin,a polysaccharide,which enable this molecule to be water soluble are connected with ________ linkages.

A)b-1,4'-glycosidic
B)a-1,4'-glycosidic
C)a-1,6'-glycosidic
D)b-1,6'-glycosidic

Question 41

What is the classification of pyranose forms of monosaccharides?

A)5-Membered cyclic hemiacetals
B)6-Membered cyclic acetals
C)5-Membered cyclic acetals
D)6-Membered cyclic hemiacetals

Question 42

Which of the following is a polysaccharide?

A)Cellulose
B)Starch
C)Glycogen
D)All of these choices are correct

Question 43

Which of the following is D-sorbose?

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

Question 44

Which of the following is D-fructose?

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

Question 45

What is the Fischer projection of the monosaccharide from which the following glycoside was prepared?

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

Question 46

Which of the following is D-glucose?

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

Question 47

What is the Fischer projection of the monosaccharide from which the following glycoside was prepared?

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

Question 48

What is the Haworth projection of the α anomer of a monosaccharide epimeric with D-glucose at C3?

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

Question 49

Which of the following is a disaccharide?

A)Maltose
B)Lactose
C)Sucrose
D)All of these choices are correct

Question 50

Which of the following is D-galactose?

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