Question 1

Which of the following best describes the structural difference between an aldose and a ketose sugar?

Accepted Answer

An aldose contains a carbonyl group at the end of the carbon chain, while a ketose contains a carbonyl group within the carbon chain.

Question 2

How many possible stereoisomers exist for an aldohexose?

Accepted Answer

$$2^4 = 16$

Question 3

Which of the following statements about epimers is correct?

Accepted Answer

Epimers are diastereomers that differ at only one chiral center.

Question 4

Which of the following is a reducing disaccharide?

Accepted Answer

Maltose

Question 5

What is the main structural difference between amylose and amylopectin?

Accepted Answer

Amylose is unbranched with $$\alpha 1 \rightarrow 4$$ linkages, while amylopectin is branched with $$\alpha 1 \rightarrow 6$$ linkages at branch points.

Question 6

Which of the following best explains why cellulose is insoluble and difficult to digest for most animals?

Accepted Answer

Cellulose has $$\beta 1 \rightarrow 4$$ glycosidic bonds and extensive hydrogen bonding between chains.

Question 7

A solution of pure $$\alpha-D-$$glucose is dissolved in water. Over time, the optical rotation changes until it stabilizes. What is this phenomenon called?

Accepted Answer

Mutarotation

Question 8

Which of the following correctly describes the glycosidic bond in sucrose?

Accepted Answer

$$\alpha 1 \rightarrow 2 \beta$$

Question 9

Which of the following is a function of glycoproteins in biological systems?

Accepted Answer

Protein-protein recognition and immune system evasion by viruses

Question 10

Which of the following best describes the repeating unit in chitin?

Accepted Answer

N-acetylglucosamine with $$\beta 1 \rightarrow 4$$ linkages

Question 11

Which of the following statements about the reducing properties of carbohydrates is correct?

Accepted Answer

A carbohydrate is reducing if it has a free hemiacetal or hemiketal group.

Question 12

Which of the following is a correct description of anomeric carbons?

Accepted Answer

The anomeric carbon is the new chiral center formed during cyclization of a monosaccharide.

Question 13

Which of the following best explains why glycogen is more highly branched than amylopectin?

Accepted Answer

Glycogen has $$\alpha 1 \rightarrow 6$$ branches every 8–12 residues, while amylopectin branches every 24–30 residues.

Question 14

Which of the following is a correct statement about the structure of agarose?

Accepted Answer

Agarose is a heteropolysaccharide with alternating $$\beta 1 \rightarrow 4$$ and $$\alpha 1 \rightarrow 3$$ glycosidic bonds.

Question 15

A patient is diagnosed with a deficiency in the enzyme that hydrolyzes $$\beta 1 \rightarrow 4$$ glycosidic bonds. Which dietary polysaccharide will be most affected?

Accepted Answer

Cellulose

Question 16

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

Accepted Answer

O-linked glycoproteins have carbohydrates attached to the hydroxyl group of serine or threonine, while N-linked glycoproteins have carbohydrates attached to the amide nitrogen of asparagine.

Question 17

Which of the following is a correct statement about the function of extracellular matrix (ECM) carbohydrates?

Accepted Answer

They provide strength, elasticity, and act as a barrier to tumor cell invasion.

Question 18

Which of the following is a correct description of mutarotation?

Accepted Answer

The change in optical rotation as a monosaccharide equilibrates between its $$\alpha$$ and $$\beta$$ anomeric forms in solution.

Carbohydrates: Structure, Stereochemistry, Cyclization, and Biological Roles

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