Question 1

Which of the following is NOT a function of carbohydrates in biological systems?

Accepted Answer

Acting as enzymes to catalyze biochemical reactions

Question 2

Which general formula represents a monosaccharide with $$n$$ carbon atoms?

Accepted Answer

$$C_n(H_2O)_n$$

Question 3

Which statement best describes the difference between aldoses and ketoses?

Accepted Answer

Aldoses contain an aldehyde group, while ketoses contain a ketone group.

Question 4

Which of the following is a triose ketose?

Accepted Answer

Dihydroxyacetone

Question 5

Monosaccharides are chiral molecules. What does this mean?

Accepted Answer

They have at least one carbon atom bonded to four different substituents.

Question 6

Which projection is most commonly used to represent the stereochemistry of monosaccharides?

Accepted Answer

Fischer projection

Question 7

Which of the following pairs are diastereomers?

Accepted Answer

D-Threose and L-Erythrose

Question 8

What is the difference between an epimer and an anomer?

Accepted Answer

Epimers differ in configuration at one carbon other than the anomeric carbon; anomers differ at the anomeric carbon.

Question 9

Cyclization of a monosaccharide creates a new asymmetric center. What is this center called?

Accepted Answer

Anomeric center

Question 10

Which of the following is a correct description of a glycosidic bond?

Accepted Answer

A covalent bond formed by the elimination of water between the anomeric carbon of a cyclic saccharide and the hydroxyl group of another compound.

Question 11

Which of the following is a derivative of glucose formed by reduction of its carbonyl group?

Accepted Answer

D-Glucitol (sorbitol)

Question 12

Which of the following is true about sugar phosphates?

Accepted Answer

They are important intermediates in metabolism and function as activated compounds in syntheses.

Question 13

Which of the following is a correct abbreviation for the disaccharide sucrose?

Accepted Answer

$$\alpha-D-$$Glcp(1 \rightarrow 2)-\beta$-D-Fruf

Question 14

Why is the formation of glycosidic bonds thermodynamically unfavored?

Accepted Answer

The standard free energy change ($$\Delta G^\circ) $$for glycosidic bond formation is about $$+15 kJ/$$mol, requiring activation.

Question 15

Which activated sugar is used in lactose biosynthesis?

Accepted Answer

UDP-galactose

Question 16

Which of the following statements about starch and glycogen is correct?

Accepted Answer

Starch contains both amylose (unbranched) and amylopectin (branched), while glycogen is more highly branched and has shorter branch points.

Question 17

Which linkage is found in cellulose, the major structural polysaccharide in plants?

Accepted Answer

$$\beta-1$$,4-glycosidic linkage

Question 18

Which of the following is a homopolymer of N-acetyl-D-glucosamine and a major component of arthropod exoskeletons?

Accepted Answer

Chitin

Question 19

Which type of glycoprotein linkage involves attachment of the oligosaccharide to the side chain amide group of asparagine?

Accepted Answer

N-linked glycoprotein

Carbohydrates: Structure, Classification, and Biological Roles

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