Deck 7: Carbohydrates and the Glycoconjugates of Cell Surfaces

Question 1

Which of the following sugars has xylulose as an epimer?

A)sorbose
B)ribulose
C)arabinose
D)xylose

Answer 1

B

Question 2

Which of the following alcohols is a constituent of the flavin coenzymes?

A)sorbitol
B)mannitol
C)xylitol
D)ribitol

Answer 2

D

Question 3

Which of the following is part of the honeybee's processing of honey?

A)producing a large amount of gluconic acid
B)reduce the concentration of the sugars to an unsaturated state
C)producing an emulsion of glucose hydrate and fructose hydrate crystals in a thick syrup
D)conversion of some glucose and fructose into sucrose

Answer 3

C

Question 4

Which of the following is a chemical feature that is characteristic of carbohydrates?

A)the potential to form no more than 2 hydrogen bonds
B)the existence of 1 or more symmetric centres
C)the ability to exist in ring but not linear structures
D)the capacity to form polymeric structures

Question 5

Which form of D-glucose does NOT exist as a result of mutarotation?

A)L-glucopyranose
B)b-anomer
C)free aldehyde
D)a-anomer

Question 6

Which of the following alcohols is NOT a sugar alcohol?

A)ribitol
B)sorbitol
C)glycerol
D)mannitol

Question 7

Which of the following functional groups does an alcohol react with when forming cyclic structures in sugars,resulting in the creation of an additional asymmetric centre?

A)a secondary alcohol
B)a phosphate group
C)a thiol group
D)an aldehyde or a ketone

Question 8

Which of the following sugars is an aldopentose?

A)galactose
B)ribulose
C)ribose
D)xylulose

Question 9

Which of the following statements concerning pairs of sugars is correct?

A)Glyceraldehyde and dihydroxyacetone are stereoisomers.
B)Glucose has fewer chiral centres than fructose.
C)Galactose and fructose are diastereomers.
D)Glucose and fructose are epimers.

Question 10

Which of the following pair of glycosamines is linked to 3-carbon acids at the C-1 or C-3 positions,and are components of the polysaccharides of higher organisms and bacterial cell walls?

A)glucosides and galactosides
B)muramic acid and neuraminic acid
C)gluconic acid and glucuronic acid
D)sorbitol and ribitol

Question 11

Which of the following terms refers to a cyclic hemiacetal with a 6-membered,oxygen-containing ring?

A)aldehyde
B)pyranose
C)ketopentose
D)furanose

Question 12

Which of the following statements is NOT correct regarding cyclic sugars?

A)The a-anomer has the -OH of the anomeric carbon positioned on the opposite side of the sugar ring from the -CH₂OH.
B)The 5- and 6-membered rings are more frequently observed due to stability.
C)In a chair conformation,the predominant form has the bulkiest substituents occupying axial positions.
D)They can be formed by the intramolecular reactions to hemiacetals or hemiketals.

Question 13

Which of the following structures does glucose most commonly form?

A)a pyranose using the hydroxyl group on carbon 4
B)a pyranose using the hydroxyl group on carbon 5
C)a furanose using the hydroxyl group on carbon 3
D)a furanose using the hydroxyl group on carbon 4

Question 14

Which of the following compounds has a glycosidic bond?

A)b-D-galactosamine
B)methyl-b-D-glucoside
C)b-D-glucose-6-phosphate
D)a-D-fructose-1,6-bisphosphate

Question 15

?-D-Glucopyranose in the chair form is the most widely occurring form of glucose in nature.Which of the following is one of its characteristics?

A)The anomeric carbon has a hydroxyl that is below the plane of the chair.
B)It forms a 5-membered ring.
C)Carbon 6 is below the plane of the chair.
D)All the -OH groups are equatorial.

Question 16

Which of the following sugars is the enantiomer of D-mannose?

A)L-mannose
B)D-glucose
C)D-galactose
D)L-arabinose

Question 17

Individuals with uncontrolled diabetes mellitus may have elevated levels of blood glucose.As a result of this,which of the following is their blood normally tested for?

A)reducing sugars
B)oxidizing sugars
C)fructose
D)gluconic acid

Question 18

Which of the following are the predominant components of honey?

A)sucrose and mannitol
B)glucose and ribose
C)fructose and glucose
D)sucrose and sorbitol

Question 19

Which of the following disaccharides contains an a(14)O-glycosidic bond?

A)sucrose
B)lactose
C)maltose
D)cellobiose

Question 20

If carbon 1 is the carbonyl group of an aldohexose,which of the following carbons determines if the sugar is a D- or an L-stereoisomer?

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

Question 21

Which of the following sugars is NOT a homodisaccharide?

A)lactose
B)maltose
C)isomaltose
D)cellobiose

Question 22

Cellulose is extremely resistant to hydrolysis,but cellulase can catalyze its hydrolysis.Which of the following is the source of cellulase?

A)the pancreas
B)bacteria that live in the rumen
C)H⁺ secreted into the rumen
D)the intestinal wall

Question 23

Which of the following terms classifies the enzyme cellulase?

A)a(14)glucosidase
B)b(14)glucosidase
C)a(16)glucosidase
D)b(16)glucosidase

Question 24

Which of the following substances is a mucopolysaccharide that forms protective coats on animal cells?

A)chitin
B)glycogen
C)glucuronic acids
D)hyaluronic acids

Question 25

Which of the following dissaccharides represents trehalose,blood sugar in hemolymph of insects?

A)GlcaaGlc
B)Glca4Glc
C)Galb4Glc
D)Glcb4Glc

Question 26

Which of the following is correct regarding the nature of glycogen?

A)It is a trisaccharide used for storage.
B)It has all non-reducing ends.
C)It is a branched polymer of linked glucose residues.
D)It is found primarily in the brain and skeletal muscles.

Question 27

Which of the following is a feature of dextrans?

A)They are synthesized from fructose.
B)They are used in research laboratories as a support for ion exchange chromatography.
C)They are repeating units of maltose.
D)The branches may be 1à2,1à3,or 1à4 in various species.

Question 28

Osmotic pressure is greatly reduced by formation of polysaccharide molecules from monosaccharide molecules.Which of the following does osmotic pressure depend on to accomplish this?

A)molecular weight
B)number of hydroxyl groups
C)numbers of molecules
D)numbers of hydrogen bonds

Question 29

Which of the following compounds is typical of the oligosaccharide components found in beans,etc.,that are not digested in the stomach,but are digested by bacteria in the intestines,causing flatulence?

A)dextrantriose
B)melezitose
C)maltose
D)stachyose

Question 30

Which of the following carbons of glucose is oxidized upon formation of glucuronic acid?

A)C-1
B)C-2
C)C-4
D)C-6

Question 31

Which of the following enzymes is found in liver and muscle tissue and is used to catalyze the hydrolysis of glycogen to glucose-1-phosphate?

A)glycogen phosphorylase
B)b(1à6)-glucosidase
C)a-amylase
D)glycogen maltase

Question 32

Which of the following sugars is commonly referred to as cellulose?

A)(1à4)-a-D-mannopyranan
B)(1à4)-b-D-glucopyranan
C)(1à6)-a-D-mannopyranan
D)(1à6)-a-D-glucopyranan

Question 33

Which of the following characteristics is common to both cellulose and a-amylose?

A)Both are linear homopolymers of glucose.
B)Both have (1à4)linkages.
C)Both form an extended ribbon,the most stable conformation.
D)Both have extensive intramolecular hydrogen bonding.

Question 34

Which of the following statements explains why cooked starch is more digestible than uncooked starch?

A)It has been partially hydrolyzed during cooking.
B)The amylopectin is converted to amylose during cooking.
C)The enzymes that hydrolyze the starch are active only when the starch is hot.
D)The starch granules take up water,swell,and are more accessible to the enzymes.

Question 35

In plant cells,starch is hydrolyzed by starch phosphorylase.Which of the following is released upon hydrolysis?

A)glucose-1-phosphate and a starch molecule with 1 less glucose unit
B)glucose-6-phosphate and a starch molecule with 1 less glucose unit
C)maltose-1-phosphate and a starch molecule with 2 less glucose units
D)maltose-6-phosphate and a starch molecule with 2 less glucose units

Question 36

Neither a-amylase nor b-amylase can cleave the a(1à6)glycosidic bonds of amylopectin.Which of the following enzymes is required to completely hydrolyze starch?

A)a(1à6)-glucosidase
B)glycogen phosphorylase
C)maltase
D)sucrase

Question 37

Which of the following disaccharides is NOT a reducing sugar?

A)lactose
B)maltose
C)sucrose
D)cellulose

Question 38

Which of the following statements explains why the disaccharide sucrose is a reducing sugar?

A)The primary hydroxyl groups are reduced to carboxylic acids.
B)It is composed of a furanose and a pyranose.
C)Both anomeric carbons are involved in formation of the glycosidic bond.
D)The glycosidic bond is in the b configuration.

Question 39

Which of the following does NOT apply to both cellulose and chitin?

A)Both are polymers of glucose.
B)Both are structural polysaccharides.
C)Both have extended ribbon conformations.
D)Both have extensive hydrogen bonding.

Question 40

Which of the following is a characteristicof cellulose fibre?

A)It is a linear polymer of b(14)glycosidic-linked glucose and galactose residues.
B)It is extremely susceptible to hydrolysis.
C)It is made up of very weak microfibrils.
D)Intermolecular hydrogen bonds play a major role in the stabilization of microfibrils.

Question 41

Which of the following represents an example of a proteoglycan?

A)attachment of several molecules of heparin to the peptide antithrombin III
B)attachment of a Gal-b(1,3)-GalNAc disaccharide to the fish antifreeze protein
C)attachment of a small oligosaccharide to an immunoglobulin
D)attachment of a small antigenic determinant to a membrane-bound protein of a cell

Question 42

Which of the following are important components of the vitreous humour of the eye and of synovial fluid that lubricates the joints?

A)heparins
B)hyaluronates
C)chondroitins
D)keratin sulfates

Question 43

Which of the following is non-covalently attached to the core protein of a proteoglycan?

A)oligosaccharide
B)glycosaminoglycan
C)hyaluronic acid backbone
D)keratin sulfate

Question 44

Which of the following are proteoglycans,a group of macromolecules,formed from?

A)proteases and monosaccharides
B)proteases and glycosaminoglycans
C)proteins and monosaccharides
D)proteins and glycosaminoglycans

Question 45

Glycosaminoglycans are unbranched polysaccharides consisting of alternating residues of uronic acid and hexosamine.Which of the following is NOT a glycosaminoglycan?

A)agaropectin
B)heparin
C)dermatan sulfate
D)hyaluronate

Question 46

Which of the following is a property of cartilage matrix proteoglycan?

A)It contains only N-linked oligosaccharides.
B)It is responsible for the inflexibility of cartilage.
C)It is has a hyaluronic acid binding domain.
D)It is an integral transmembrane protein.

Question 47

Which of the following pairs of molecules is found in tendons,cartilage,and other connective tissue?

A)heparin and chondroitins
B)chondroitins and keratin sulfate
C)keratin sulfate and dermatan sulfate
D)hyaluronate and keratin sulfate

Question 48

Which of the following regarding agarose is correct?

A)Agarose readily forms gels that are only 50% water.
B)Agarose forms a double helix with a central core large enough to accommodate large quantities of water.
C)Agarose consists of only a linear component.
D)Agarose is a chain of alternating D-glucose and 3,6-anhydro-L-galactose,with side-chains of 6-methyl-D-glucose.