Question 1

Which of the following best explains why storage of glucose as glycogen in liver cells is physiologically advantageous compared to storing glucose as free monomers?

Accepted Answer

Storing glucose as glycogen reduces the osmolarity of the cytosol, preventing cell swelling and lysis due to water influx.

Question 2

Which of the following statements about the structure of cellulose is correct?

Accepted Answer

Cellulose is a linear polymer of D-glucose units linked by (\beta1\rightarrow4) glycosidic bonds, forming extended chains stabilized by intermolecular hydrogen bonds.

Question 3

A patient is found to have a deficiency in the enzyme that hydrolyzes (\beta1\rightarrow4) glycosidic bonds. Which dietary component will be most difficult for them to digest?

Accepted Answer

Cellulose

Question 4

Which of the following best describes an epimer?

Accepted Answer

A sugar that differs from another only in the configuration around one specific carbon atom.

Question 5

Which of the following is a correct statement about the difference between D- and L- isomers of monosaccharides?

Accepted Answer

D- and L- isomers differ in the configuration around the chiral center most distant from the carbonyl carbon.

Question 6

Which of the following best explains why most naturally occurring hexoses in living organisms are D-isomers?

Accepted Answer

Biological evolution selected one stereochemical series (D-series) for sugars, similar to the selection of L-amino acids in proteins.

Question 7

Which of the following is a reducing sugar?

Accepted Answer

Lactose

Question 8

A glycosidic bond is formed when:

Accepted Answer

A hydroxyl group of one sugar reacts with the anomeric carbon of another sugar.

Question 9

Which of the following best describes the structure and function of glycosaminoglycans in the extracellular matrix?

Accepted Answer

They are linear heteropolysaccharides composed of repeating disaccharide units, providing viscosity, adhesiveness, and tensile strength to the extracellular matrix.

Question 10

Which of the following statements about the three-dimensional structure of polysaccharides is correct?

Accepted Answer

Starch folds into a helical structure stabilized by internal hydrogen bonds, while cellulose forms an extended structure stabilized by intermolecular hydrogen bonds.

Question 11

Which of the following best describes the role of lectins in biological systems?

Accepted Answer

Lectins are proteins that bind carbohydrates with high specificity and mediate cell-cell recognition, signaling, and adhesion.

Question 12

Which of the following is a correct description of the difference between amylose and amylopectin?

Accepted Answer

Amylose contains (\alpha1\rightarrow4) linkages only, while amylopectin contains both (\alpha1\rightarrow4) and (\alpha1\rightarrow6) linkages.

Question 13

Which of the following best explains why phosphorylated derivatives of sugars, such as glucose 6-phosphate, are trapped inside cells?

Accepted Answer

Most cells lack membrane transporters for phosphorylated sugars, so these molecules cannot cross the membrane.

Question 14

Which of the following is a correct statement about the synthesis of complex polysaccharides?

Accepted Answer

The sequence is determined by the intrinsic properties of the biosynthetic enzymes that add each monomeric unit.

Question 15

Which of the following best describes the structure of chitin?

Accepted Answer

Chitin is a linear homopolysaccharide of N-acetylglucosamine residues linked by (\beta1\rightarrow4) bonds.

Question 16

Which of the following is a correct statement about the informational role of oligosaccharides in glycoproteins?

Accepted Answer

Oligosaccharides provide critical information for protein targeting and allow specific recognition by other proteins.

Question 17

A scientist is analyzing a new polysaccharide and finds it is composed of two different monosaccharide units arranged in a repeating pattern. Which class does this polysaccharide belong to?

Accepted Answer

Heteropolysaccharide

Question 18

Which of the following best describes the difference between O-linked and N-linked glycoproteins?

Accepted Answer

O-linked glycoproteins have oligosaccharides attached to the hydroxyl group of Ser or Thr residues, while N-linked glycoproteins have oligosaccharides attached to the amide nitrogen of Asn residues.

Carbohydrates and Glycobiology: Structure, Function, and Analysis

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