,CHEM212/CHEM 212 Module 4 Exam Biochemistry
with Lab | Portage Learning | 26/27 Actual(PDF)
1. Which monosaccharide is classified as a ketose?
A) Glucose
B) Dihydroxyacetone
C) Galactose
D) Ribose
Correct Answer: Dihydroxyacetone
Rationale: Dihydroxyacetone contains a ketone group on its second carbon, classifying it as a ketose.
Glucose and galactose are aldoses with an aldehyde group at carbon 1, and ribose is an aldose
pentose. Ketoses such as dihydroxyacetone and fructose are distinguished by the position of the
carbonyl group.
2. Two monosaccharides that differ only in the configuration about a single carbon atom are called:
A) Anomers
B) Enantiomers
C) Epimers
D) Rotamers
Correct Answer: Epimers
Rationale: Epimers are diastereoisomers that differ in configuration at exactly one chiral carbon.
Anomers differ specifically at the anomeric carbon, enantiomers are mirror images differing at all
chiral centers, and rotamers differ by rotation about a single bond. Glucose and galactose are classic
epimers at carbon 4.
3. Which pair of sugars represents an anomeric relationship?
A) D-glucose and D-fructose
,B) alpha-D-glucose and beta-D-glucose
C) D-glucose and L-glucose
D) D-glucose and D-mannose
Correct Answer: alpha-D-glucose and beta-D-glucose
Rationale: Anomers differ only in the configuration at the anomeric carbon, which is carbon 1 in
glucose. The alpha and beta forms of D-glucose interconvert through mutarotation. D-glucose and D-
fructose differ as aldose and ketose, D-glucose and L-glucose are enantiomers, and D-glucose and D-
mannose are epimers at carbon 2.
4. Which carbon determines whether a monosaccharide is classified as the D or L configuration?
A) The anomeric carbon
B) The carbonyl carbon
C) The penultimate carbon
D) The terminal carbon
Correct Answer: The penultimate carbon
Rationale: The D or L designation is determined by the configuration at the penultimate carbon, which
is the chiral carbon farthest from the carbonyl group. In glucose, this is carbon 5. If the hydroxyl group
is on the right in the Fischer projection, the sugar is D; if on the left, it is L.
5. What type of bond connects two monosaccharides in a disaccharide?
A) A peptide bond
B) An ester bond
C) A glycosidic bond
D) A phosphodiester bond
Correct Answer: A glycosidic bond
, Rationale: Disaccharides are formed when two monosaccharides are joined by a glycosidic bond,
typically between the anomeric carbon of one sugar and a hydroxyl group of the other. Peptide bonds
connect amino acids, ester bonds appear in lipids, and phosphodiester bonds link nucleotides.
6. Which polysaccharide serves as the primary storage form of glucose in animals?
A) Cellulose
B) Starch
C) Glycogen
D) Chitin
Correct Answer: Glycogen
Rationale: Glycogen is a highly branched glucose polymer stored primarily in the liver and muscle of
animals. Starch is the storage polysaccharide of plants, cellulose provides structural support in plant
cell walls, and chitin forms exoskeletons of arthropods.
7. Cellulose and chitin are both polymers of glucose derivatives. What distinguishes chitin from
cellulose?
A) Chitin contains alpha-1,4 linkages
B) Chitin has N-acetylglucosamine residues
C) Chitin is a branched polysaccharide
D) Chitin contains galactose instead of glucose
Correct Answer: Chitin has N-acetylglucosamine residues
Rationale: Chitin is a polymer of N-acetylglucosamine, which is glucose with an acetamido group at
carbon 2, linked by beta-1,4 glycosidic bonds. Cellulose is a polymer of unmodified glucose with beta-
1,4 linkages. Chitin is unbranched, like cellulose.
8. A carbohydrate with the molecular formula C₅H₁₀O₅ is classified as which of the following?
with Lab | Portage Learning | 26/27 Actual(PDF)
1. Which monosaccharide is classified as a ketose?
A) Glucose
B) Dihydroxyacetone
C) Galactose
D) Ribose
Correct Answer: Dihydroxyacetone
Rationale: Dihydroxyacetone contains a ketone group on its second carbon, classifying it as a ketose.
Glucose and galactose are aldoses with an aldehyde group at carbon 1, and ribose is an aldose
pentose. Ketoses such as dihydroxyacetone and fructose are distinguished by the position of the
carbonyl group.
2. Two monosaccharides that differ only in the configuration about a single carbon atom are called:
A) Anomers
B) Enantiomers
C) Epimers
D) Rotamers
Correct Answer: Epimers
Rationale: Epimers are diastereoisomers that differ in configuration at exactly one chiral carbon.
Anomers differ specifically at the anomeric carbon, enantiomers are mirror images differing at all
chiral centers, and rotamers differ by rotation about a single bond. Glucose and galactose are classic
epimers at carbon 4.
3. Which pair of sugars represents an anomeric relationship?
A) D-glucose and D-fructose
,B) alpha-D-glucose and beta-D-glucose
C) D-glucose and L-glucose
D) D-glucose and D-mannose
Correct Answer: alpha-D-glucose and beta-D-glucose
Rationale: Anomers differ only in the configuration at the anomeric carbon, which is carbon 1 in
glucose. The alpha and beta forms of D-glucose interconvert through mutarotation. D-glucose and D-
fructose differ as aldose and ketose, D-glucose and L-glucose are enantiomers, and D-glucose and D-
mannose are epimers at carbon 2.
4. Which carbon determines whether a monosaccharide is classified as the D or L configuration?
A) The anomeric carbon
B) The carbonyl carbon
C) The penultimate carbon
D) The terminal carbon
Correct Answer: The penultimate carbon
Rationale: The D or L designation is determined by the configuration at the penultimate carbon, which
is the chiral carbon farthest from the carbonyl group. In glucose, this is carbon 5. If the hydroxyl group
is on the right in the Fischer projection, the sugar is D; if on the left, it is L.
5. What type of bond connects two monosaccharides in a disaccharide?
A) A peptide bond
B) An ester bond
C) A glycosidic bond
D) A phosphodiester bond
Correct Answer: A glycosidic bond
, Rationale: Disaccharides are formed when two monosaccharides are joined by a glycosidic bond,
typically between the anomeric carbon of one sugar and a hydroxyl group of the other. Peptide bonds
connect amino acids, ester bonds appear in lipids, and phosphodiester bonds link nucleotides.
6. Which polysaccharide serves as the primary storage form of glucose in animals?
A) Cellulose
B) Starch
C) Glycogen
D) Chitin
Correct Answer: Glycogen
Rationale: Glycogen is a highly branched glucose polymer stored primarily in the liver and muscle of
animals. Starch is the storage polysaccharide of plants, cellulose provides structural support in plant
cell walls, and chitin forms exoskeletons of arthropods.
7. Cellulose and chitin are both polymers of glucose derivatives. What distinguishes chitin from
cellulose?
A) Chitin contains alpha-1,4 linkages
B) Chitin has N-acetylglucosamine residues
C) Chitin is a branched polysaccharide
D) Chitin contains galactose instead of glucose
Correct Answer: Chitin has N-acetylglucosamine residues
Rationale: Chitin is a polymer of N-acetylglucosamine, which is glucose with an acetamido group at
carbon 2, linked by beta-1,4 glycosidic bonds. Cellulose is a polymer of unmodified glucose with beta-
1,4 linkages. Chitin is unbranched, like cellulose.
8. A carbohydrate with the molecular formula C₅H₁₀O₅ is classified as which of the following?
