Ch.16 Carbohydrates Verified Test Bank 10th Edition

General, Organic, and Biochemistry, 10e (Denniston)

Chapter 16 Carbohydrates

1) Which of the following statements concerning carbohydrates is INCORRECT?

A) Carbohydrates serve important energy and structural roles for plants and animals.

B) Monosaccharides are the simplest carbohydrates and are known as simple sugars.

C) Monosaccharides join together to form disaccharides and polysaccharides by hydrogen bonding.

D) Humans store excess glucose for short-term energy requirements in the polysaccharide glycogen.

E) Carbohydrates that can be oxidized by the Benedict's reagent are known as reducing sugars.

2) Monosaccharides are structurally defined as which of the following?

A) polyhydroxyaldehydes or polyhydroxyketones

B) hemiacetals and acetals

C) polyamides or polyesters

D) enols and enolates

E) carboxylic acids

3) Carbohydrates are chiral or "handed" biomolecules. What does the term chiral describe?

A) a molecule that has a mirror image

B) a molecule that can be superimposed on its mirror image

C) a molecule that exists in two nonsuperimposable mirror image forms

D) a molecule that can be digested by the body

E) a molecule that may be synthesized by the body

4) Which enantiomer of glyceraldehyde is represented in the following structure?

A) L-glyceraldehyde

B) α-glyceraldehyde

C) β-glyceraldehyde

D) D-glyceraldehyde

E) It is impossible to determine from the structure alone.

5) Which of the following statements concerning stereochemistry is INCORRECT?

A) Stereoisomers are molecules with the same molecular formula, same bonding pattern, but different spatial arrangement of atoms.

B) A chiral carbon is a carbon atom that has four different groups bonded to it.

C) A molecule that contains a chiral carbon is a chiral molecule, and exists as a pair of enantiomers.

D) Enantiomers are superimposable mirror image stereoisomers.

E) A racemic mixture of enantiomers is optically inactive.

6) Propranol is a chiral compound that exists as a pair of enantiomers. One enantiomer is used to treat irregular heartbeats, and the other is used as a contraceptive. Which labeled carbon atom(s) is/are chiral?

A) C-1

B) C-2

C) C-3

D) C-4

E) C-1 and C-3

7) How does the structure of α-D-glucose differ from that of β-D-glucose?

A) α-D-Glucose is an aldose and β-D-glucose is a ketose.

B) In α-D-glucose the −OH group on the last chiral carbon is on the left, and in β-D-glucose the −OH group on the last chiral carbon is on the right.

C) In α-D-glucose the −OH group on the hemiacetal carbon is below the ring, and in β-D-glucose the −OH group on the hemiacetal carbon is above the ring.

D) In α-D-glucose the last −CH2OH group is on the right, and in β-D-glucose the −CH2OH group is on the left.

E) There is no structural difference between the two.

8) Which carbohydrate is present in RNA?

A) ribulose

B) glucose

C) mannose

D) ribose

E) fructose

9) The open chain structure of D-fructose is shown. What is the Haworth projection for β-D-fructose?

A)

B)

C)

D)

E)

10) What product is formed when the monosaccharide below is oxidized by a basic solution of Benedict's reagent?

A)

B)

C)

D)

E)

11) The simplest aldose is named 2,3-dihydroxypropanal, although it is more commonly referred to as glyceraldehyde. What is the structure of glyceraldehyde?

A)

B)

C)

D)

E)

12) A ketose can be converted to an aldose through an enediol intermediate. What is the structure of the enediol intermediate when D-fructose is converted to D-glucose?

A)

B)

C)

D)

E)

13) What is a reducing sugar?

A) a carbohydrate that can be oxidized by Benedict's reagent

B) a sugar that contains an acetal

C) a carbohydrate that can be reduced by Benedict's reagent

D) a sugar that can be digested by the body

E) a carbohydrate that is part of a polysaccharide

14) What term is used to describe an excess of glucose in a urine sample?

A) glucosamine

B) glucosemia

C) glucosuria

D) hypoglucose

E) glucagon

15) What test can be used to distinguish between a reducing sugar and a nonreducing sugar?

A) iodine test

B) urine test

C) chromic acid test

D) Benedict's test

E) hydrolysis test

16) What disaccharide is composed of two glucose units joined together?

A) lactose

B) maltose

C) sucrose

D) cellulose

E) galactose

17) What two monosaccharides join to form the disaccharide lactose?

A) glucose and galactose

B) galactose and fructose

C) ribose and galactose

D) glucose and fructose

E) glucose and glucose

18) What two monosaccharides combine to form sucrose?

A) glucose and galactose

B) galactose and fructose

C) ribose and galactose

D) glucose and fructose

E) ribose and fructose

19) Starch is composed of which two polysaccharides?

A) chitin and chondroitin

B) glycogen and cellulose

C) amylose and amylopectin

D) glucosamine and glycogen

E) cellulose and galactosamine

20) Amylose and amylopectin are both components of starch. How do their structures differ?

A) Amylose is a monosaccharide and amylopectin is a polysaccharide.

B) Amylose is a polysaccharide and amylopectin is a disaccharide.

C) Amylose is an aldose and amylopectin is a ketose.

D) Amylose is a linear polysaccharide and amylopectin is a branched polysaccharide.

E) Amylose is a hexose and amylopectin is a pentose.

21) What are the major sites of glycogen storage in the human body?

A) fat and pancreas

B) liver and muscle

C) stomach and intestines

D) kidneys and stomach

E) heart and brain

22) Why are humans not able to digest cellulose?

A) Humans lack the enzyme cellulase, which is required to hydrolyze the β(1→4) glycosidic bonds present in cellulose.

B) Humans lack the enzyme lactase, which is required to hydrolyze the lactose produced from the digestion of cellulose into glucose and galactose.

C) Humans lack the enzyme lactase, which is required to convert the galactose produced from the digestion of cellulose into glucose.

D) Cellulose is not naturally available to humans.

E) Humans actually can readily digest cellulose.

23) What is the most abundant carbohydrate on Earth?

A) sucrose

B) cellulose

C) glycogen

D) fructose

E) amylose

24) How do the structures of amylose and cellulose differ?

A) Amylose is a linear polysaccharide and cellulose is a branched polysaccharide.

B) Amylose is a homopolysaccharide and cellulose is a heteropolysaccharide.

C) Amylose is a polysaccharide of glucose units, and cellulose is a polysaccharide of galactose units.

D) Amylose is a polysaccharide made up of D-glucose units, and cellulose is a polysaccharide made up of L-glucose units.

E) Amylose contains α(1→4) glycosidic bonds joining D-glucose units, and cellulose contains β(1→4) glycosidic bonds joining D-glucose units.

25) The monosaccharide derivative shown below bonds to hydrophobic molecules in the liver. What effect does this have on the molecule to which it binds?

A) It increases the hydrophobicity of the molecule, making it more soluble in fatty tissues.

B) It increases the polarity of the molecule, making it more soluble in bodily fluids, and more readily removed.

C) It eliminates the ability of the molecule to act as a nutritional source of energy.

D) It decreases the polarity of the hydrophobic molecule, allowing it to be retained in the body longer.

E) It increases the nutritional value of the molecule by allowing it to be retained by the body longer.

26) What is the simplest type of carbohydrate?

A) sugars

B) monosaccharides

C) cellulose

D) starch

E) None of the choices are correct.

27) What complex carbohydrate provides a source of dietary fiber?

A) starch

B) cellulose

C) lactose

D) sucrose

E) glucose

28) What two functional groups are present in all monosaccharides?

A) hydroxyl and carboxyl

B) alkene and phosphate

C) acid and carbonyl

D) amino and hydroxyl

E) hydroxyl and carbonyl

29) What term describes a carbon atom that has four different groups bonded to it?

A) chiral

B) unbalanced

C) trigonal pyramidal

D) meso

E) unsaturated

30) What is the stereochemical relationship between your right and left hands?

A) cis- and trans- isomers

B) structural isomers

C) conformers

D) enantiomers

E) diastereomers

31) Which monosaccharide found in the blood has its concentration regulated by the hormones insulin and glucagon?

A) fructose

B) glucose

C) galactose

D) ribose

E) sucrose

32) To what class of carbonyl-containing compounds does glucose belong?

A) aldehyde

B) ketone

C) alcohol

D) amide

E) Both aldehyde and ketone are correct.

33) What type of compound is produced in the reaction between an alcohol and an aldehyde?

A) diol

B) carboxylic acid

C) acetal

D) hemiacetal

E) ester

34) The structure of ribose, found in RNA, is shown below. How does the structure of deoxyribose, found in DNA, compare to it?

A) Deoxyribose has one less oxygen.

B) Deoxyribose has one more oxygen.

C) Deoxyribose has one less oxygen and one less hydrogen.

D) Deoxyribose has one less hydrogen.

E) Deoxyribose has one less oxygen and two less hydrogens.

35) Disaccharides and polysaccharides contain monosaccharide units joined together by which of the following?

A) dipole/dipole forces

B) hydrogen bonding

C) hemiacetal bonds

D) glycosidic linkages

E) peptide bonds

36) Which property of D-glyceraldehyde and L-glyceraldehyde differs?

A) melting point

B) solubility

C) direction of rotation of plane-polarized light

D) density

E) None of the choices are correct.

37) The Fischer projections of two monosaccharides are shown below. What is the relationship between the two monosaccharides?

A) enantiomers

B) diastereomers

C) structural isomers

D) meso isomers

E) cis-trans isomers

38) What term describes carbohydrates consisting of two to ten monosaccharide units bonded together?

A) disaccharide

B) polysaccharide

C) oligosaccharide

D) glycogen

E) starch

39) Monosaccharides exist predominantly as cyclic hemiacetals. Cyclic hemiacetals have both an α and a β form. Which of the following monosaccharides are shown in the β form?

A) III only

B) IV only

C) I and III

D) II and IV

E) All are shown in the β form.

40) The Fischer projection for the monosaccharide ribulose is shown below. How may this monosaccharide be appropriately classified?

A) ketotetrose

B) ketopentose

C) aldotriose

D) aldopentose

E) ketotriose

41) What term properly describes the relationship between the two compounds shown?

A) betamers

B) constitutional isomers

C) enantiomers

D) anomers

E) unrelated

42) Which enantiomer of glyceraldehyde is represented in the following structure?

A) trans

B) α

C) β

D) D

E) L

43) What is the molecular formula of glucose?

A) C6H12O5

B) C6H12O6

C) C6H10O5

D) C5H10O5

E) C9H18O9

44) What is the name of the simplest ketose?

A) acetone

B) fructose

C) ethanone

D) 1,3-dihydroxyacetone

E) ethose

45) What is the position of the -OH group on carbon-1 in the Haworth projection of β-D-glucose?

A) above the ring

B) below the ring

C) in the plane of the ring

D) to the left of carbon-1

E) to the right of carbon-1

46) Which form of D-glucose has the -OH group on carbon-1 below the ring in the Haworth projection?

A) meso

B) L

C) α

D) β

E) γ

47) The Fischer projection for the naturally occurring form of fucose, one of the carbohydrates used as a cell marker in the determination of blood types, is shown below. Is this D-fucose or L-fucose?

A) D-fucose

B) L-fucose

C) It is neither D- nor L-; fucose is not chiral.

D) It is impossible to determine from the Fischer projection alone.

48) What type of product forms in the intramolecular reaction between the aldehyde portion of the glucose molecule below and its C-5 hydroxyl group?

A) disaccharide

B) ester

C) carboxylic acid

D) stereoisomer

E) hemiacetal

49) A laboratory sample contains enantiomers present in equal concentrations. Which of the following statements concerning this sample is FALSE?

A) The sample contains a racemic mixture.

B) The sample will be optically inactive.

C) The sample contains two different compounds related as non-superimposable mirror image isomers.

D) The sample contains a meso compound.

50) Which monosaccharide combines with glucose to form the disaccharide lactose?

A) glucose

B) mannose

C) fructose

D) sucrose

E) galactose

51) What is the principal carbohydrate found in milk?

A) glucose

B) maltose

C) mannose

D) lactose

E) sucrose

52) Which of the following is a nonreducing disaccharide?

A) mannose

B) maltose

C) sucrose

D) lactose

E) ribose

53) Which of the following carbohydrates is also known as dextrose, and is the sugar referred to when blood sugar is measured?

A) glycogen

B) sucrose

C) glucose

D) starch

E) lactose

54) Which of the following is a highly branched polymer of glucose?

A) dextran

B) cellulose

C) amylose

D) amylopectin

E) peptidoglycan

55) What polysaccharide found in animals has a structure very similar to amylopectin?

A) glucose

B) glycogen

C) starch

D) amylose

E) cellulose

56) Melibiose is a carbohydrate found in some plant juices.  Which of the following statements concerning melibiose is INCORRECT?

A) It is a disaccharide.

B) It is composed of two different monosaccharide units.

C) It contains both an acetal and a hemiacetal.

D) It contains an α(1→5) glycosidic linkage.

E) It is a reducing sugar.

57) Gentobiose, a rare disaccharide found in saffron, produces two identical monosaccharides when it undergoes hydrolysis. What is the structure of the monosaccharide hydrolysis product?

A)

B)

C)

D)

E) None of these are correct.

58) Which of the following carbohydrates cannot be digested by humans?

A) glycogen

B) cellulose

C) amylose

D) amylopectin

E) sucrose

59) What type of glycosidic linkage between glucose units is present in cellulose?

A) α(1→4)

B) β(1→4)

C) α(1→6)

D) β(1→6)

E) α(1→4) and α(1→6)

60) What heteropolysaccharide is a component of cartilage and may relieve symptoms of osteoarthritis?

A) chondroitin sulfate

B) hyaluronic acid

C) heparin

D) glycogen

E) α-D-glucuronate

61) Which of the following is NOT a carbohydrate?

A) sucrose

B) simple sugar

C) fatty acid

D) cellulose

E) starch

62) Which of the following correctly matches the term with its definition?

A) ketose - monosaccharide with a ketone functional group

B) aldose - monosaccharide with a carbonyl group on the end carbon

C) tetrose - a four carbon sugar

D) pentose - a five carbon sugar

E) All of the choices are correct.

63) Which statement concerning a chiral carbon is always TRUE?

A) A chiral carbon is bonded to four different atoms or groups of atoms.

B) A chiral carbon is bonded to a hydroxyl group and carbonyl group.

C) A chiral carbon has two double bonds connected to it.

D) A chiral carbon causes plane-polarized light to rotate in a clockwise fashion.

E) A chiral carbon is present in all aldehydes.

64) Which statement is FALSE?

A) Molecules that contain a chiral carbon will rotate plane-polarized light.

B) If one molecule rotates plane-polarized light clockwise 10°, its enantiomer will rotate plane-polarized light counterclockwise by 10°.

C) The D- and L- designation of sugars is determined by the chiral atom farthest from the most oxidized carbon.

D) All sugars designated with a D- prefix will rotate plane-polarized light in a clockwise direction.

E) Dextrorotatory sugars rotate plane-polarized light clockwise and are designated by a plus sign (+).

65) For D-glyceraldehyde shown below, which carbon, if any, is chiral?

A) C-1

B) C-2 and C-3

C) C-2

D) None of the carbon atoms are chiral.

E) C-3

66) Which of the following is NOT a common name for D-glucose?

A) table sugar

B) dextrose

C) grape sugar

D) blood sugar

E) All of the choices are correct.

67) Aldaric acids are a type of monosaccharide derivative, formed when both the aldehyde group and the terminal –CH2OH group of a monosaccharide are oxidized to carboxylic acids. D-Glucaric acid is the aldaric acid derivative of D-glucose. What is the structure of D-glucaric acid?

A) I

B) II

C) III

D) IV

E) V

68) Which of the following is NOT a term that would properly describe glucose as it is shown below?

A) monosaccharide

B) aldose

C) hemiacetal

D) D-sugar

E) reducing sugar

69) Which of the following is the major storage molecule of glucose in animals?

A) cellulose

B) sucrose

C) blood sugar

D) amylose

E) glycogen

70) Enantiomers are related as non-superimposable mirror images.

71) A meso compound is a chiral compound because it contains two chiral carbons and an internal plane of symmetry.

72) All monosaccharides give a positive result with Benedict's reagent.

73) The glycosidic linkages found in most disaccharides and polysaccharides are acetal bonds.

74) The principal carbohydrate in milk is galactose.

75) If left untreated, galactosemia leads to mental retardation.

76) Cellulose molecules are all unbranched, while starch contains only branched molecules.

77) Humans can digest glucose polymers containing α(1→4) glycosidic linkages, but not those with β(1→4) linkages.

78) A termite's digestive organs produce a cellulase that allows it to break down wood fibers.

79) If D-glucose is levorotatory, then L-glucose must be levorotatory as well.

80) Biological molecules do not undergo the same reactions as organic molecules because their functional groups have different reactivities.

81) Which of the following may be used as a strategy in learning biochemistry?

A) recognize that the roots in various terms are unrelated and do not follow a pattern

B) memorize each new reaction because biological molecules react differently than organic molecules

C) begin each chapter by memorizing the names of the enzymes along with their substrates and products

D) focus on each detail before reviewing how they relate to an overall process

E) understand the big concepts before mastering the details