Test Bank Answers Carbohydrates Chapter 26

Organic Chemistry, 6e (Smith)

Chapter 26 Carbohydrates

1) Which of the following compounds is an aldose?

A) A

B) B

C) C

D) D

2) How many carbons does a pentose sugar have?

A) 2

B) 3

C) 4

D) 5

3) How many possible stereoisomers are there of the following heptose?

A) 16

B) 21

C) 32

D) 64

4) 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.

5) Which of the following compounds is a b anomer?

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

9) 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.

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

A) Racemization

B) Mutarotation

C) Epimerization

D) Enolization

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

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

13) 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

14) Which of the following is a reducing sugar?

A) A

B) B

C) C

D) D

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

A) PCC

B) Ag2O in NH4OH

C) FeCl3

D) HNO3

16) 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

17) What are the products of the following reaction?

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

E) E

19) 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

20) 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

21) 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

22) 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

23) 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

24) 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

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

A) A

B) B

C) C

D) D

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

A) Sucrose

B) Maltose

C) Lactose

D) Xylobiose

27) Upon hydrolysis of cellulose, what sugar is formed?

A) Sucrose

B) Maltose

C) Lactose

D) Glucose

28) Upon hydrolysis of amylose, what sugar is formed?

A) Sucrose

B) Maltose

C) Lactose

D) Glucose

29) Upon hydrolysis of amylopectin, what sugar is formed?

A) Sucrose

B) Maltose

C) Lactose

D) Glucose

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

A) A

B) B

C) C

D) D

31) 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.

32) 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

33) Which sugar is represented by the line angle structure below?

A) D-fructose

B) D-sorbose

C) L-psicose

D) L-tagatose

34) 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

35) 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

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

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

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

A) A

B) B

C) C

D) D

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

A) Enantiomers

B) Epimers

C) Anomers

D) Constitutional isomers

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

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

A) I

B) II

C) III

D) IV

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

A) I

B) II

C) III

D) IV

44) 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

45) Which of the following is D-fructose?

A) I

B) II

C) III

D) IV

46) Which of the following is D-sorbose?

A) I

B) II

C) III

D) IV

47) Which of the following is D-glucose?

A) I

B) II

C) III

D) IV

48) Which of the following is D-galactose?

A) I

B) II

C) III

D) IV

49) Which of the following is a disaccharide?

A) Maltose

B) Lactose

C) Sucrose

D) All of these choices are correct

50) Which of the following is a polysaccharide?

A) Cellulose

B) Starch

C) Glycogen

D) All of these choices are correct