CHEM 210 Module 6 Practice Exam - Page 1
, CHEM 210 Module 6 Practice Exam
Biochemistry - Portage Learning aligned study material
Q & A | 2026/2027 Edition
100 independently authored multiple-choice questions with full-text answers and rationales
Scope: nucleic acids, nucleotide structure, DNA and RNA composition, polymer formation, strand polarity, base
pairing, duplex properties, and RNA functions.
CHEM 210 Module 6 Exam | Biochemistry |
Portage | Q & A | 26/27 Actual (PDF)
1. At the monomer level, what combination defines a nucleotide?
A) A nitrogenous base and a pentose sugar only
B) A nitrogenous base, a pentose sugar, and one or more phosphate groups
C) A pentose sugar and an amino group only
D) A nitrogenous base and one or more phosphate groups without sugar
Correct Answer: A nitrogenous base, a pentose sugar, and one or more phosphate groups
Rationale: A nitrogenous base, a pentose sugar, and one or more phosphate groups is correct because a
nucleotide contains all three components: base, pentose, and phosphate. The distractors instead confuse
related components, bond types, orientations, or structural roles. This matches established nucleotide
composition, backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are
chemically inconsistent.
2. While labeling a nucleotide diagram, what feature distinguishes a nucleoside from a nucleotide?
A) A nucleoside lacks the phosphate group present in a nucleotide
B) A nucleoside lacks a nitrogenous base
C) A nucleoside contains two sugars
D) A nucleoside always contains thymine
Correct Answer: A nucleoside lacks the phosphate group present in a nucleotide
Rationale: A nucleoside lacks the phosphate group present in a nucleotide is correct because a nucleoside
consists of a base covalently linked to a pentose but no phosphate. The distractors instead confuse related
components, bond types, orientations, or structural roles. This matches established nucleotide composition,
backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are chemically
inconsistent.
CHEM 210 Module 6 Practice Exam - Page 2
, 3. During carbon-numbering analysis, which carbon is normally bonded to the nitrogenous base in a
nucleoside?
A) The 2' carbon
B) The 3' carbon
C) The 1' carbon
D) The 5' carbon
Correct Answer: The 1' carbon
Rationale: The 1' carbon is correct because the nitrogenous base is attached to the pentose at C1' through an
N-glycosidic linkage. C2' distinguishes ribose from deoxyribose, c3' participates in chain extension, and c5'
commonly bears phosphate. This matches established nucleotide composition, backbone bonding, strand
polarity, and base-pairing principles, so the alternative choices are chemically inconsistent.
4. In a bond-identification exercise, what bond joins a nitrogenous base to its pentose sugar?
A) A peptide bond
B) A phosphodiester bond
C) A disulfide bond
D) An N-glycosidic bond
Correct Answer: An N-glycosidic bond
Rationale: An N-glycosidic bond is correct because the base-sugar connection is an N-glycosidic bond between
the pentose C1' and a ring nitrogen of the base. Peptide bonds join amino acids, phosphodiester bonds join
nucleotides in the backbone, and disulfides link cysteine residues. This matches established nucleotide
composition, backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are
chemically inconsistent.
5. When two nucleotides become covalently linked, what covalent linkage forms the repeating backbone
connection?
A) A peptide bond
B) A 3'-5' phosphodiester bond
C) A hydrogen bond
D) A 2'-2' glycosidic bond
Correct Answer: A 3'-5' phosphodiester bond
Rationale: A 3'-5' phosphodiester bond is correct because adjacent nucleotides are connected by a phosphate
esterified to the 3' oxygen of one sugar and the 5' position of the next. The distractors instead confuse related
components, bond types, orientations, or structural roles. This matches established nucleotide composition,
backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are chemically
inconsistent.
6. For a newly synthesized nucleic-acid chain, what chemical feature gives the strand directionality?
A) Identical phosphate groups at both ends
B) A purine at one end and a pyrimidine at the other
C) Hydrogen bonds between adjacent sugars
D) Chemically distinct 5' and 3' ends
Correct Answer: Chemically distinct 5' and 3' ends
CHEM 210 Module 6 Practice Exam - Page 3
, CHEM 210 Module 6 Practice Exam
Biochemistry - Portage Learning aligned study material
Q & A | 2026/2027 Edition
100 independently authored multiple-choice questions with full-text answers and rationales
Scope: nucleic acids, nucleotide structure, DNA and RNA composition, polymer formation, strand polarity, base
pairing, duplex properties, and RNA functions.
CHEM 210 Module 6 Exam | Biochemistry |
Portage | Q & A | 26/27 Actual (PDF)
1. At the monomer level, what combination defines a nucleotide?
A) A nitrogenous base and a pentose sugar only
B) A nitrogenous base, a pentose sugar, and one or more phosphate groups
C) A pentose sugar and an amino group only
D) A nitrogenous base and one or more phosphate groups without sugar
Correct Answer: A nitrogenous base, a pentose sugar, and one or more phosphate groups
Rationale: A nitrogenous base, a pentose sugar, and one or more phosphate groups is correct because a
nucleotide contains all three components: base, pentose, and phosphate. The distractors instead confuse
related components, bond types, orientations, or structural roles. This matches established nucleotide
composition, backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are
chemically inconsistent.
2. While labeling a nucleotide diagram, what feature distinguishes a nucleoside from a nucleotide?
A) A nucleoside lacks the phosphate group present in a nucleotide
B) A nucleoside lacks a nitrogenous base
C) A nucleoside contains two sugars
D) A nucleoside always contains thymine
Correct Answer: A nucleoside lacks the phosphate group present in a nucleotide
Rationale: A nucleoside lacks the phosphate group present in a nucleotide is correct because a nucleoside
consists of a base covalently linked to a pentose but no phosphate. The distractors instead confuse related
components, bond types, orientations, or structural roles. This matches established nucleotide composition,
backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are chemically
inconsistent.
CHEM 210 Module 6 Practice Exam - Page 2
, 3. During carbon-numbering analysis, which carbon is normally bonded to the nitrogenous base in a
nucleoside?
A) The 2' carbon
B) The 3' carbon
C) The 1' carbon
D) The 5' carbon
Correct Answer: The 1' carbon
Rationale: The 1' carbon is correct because the nitrogenous base is attached to the pentose at C1' through an
N-glycosidic linkage. C2' distinguishes ribose from deoxyribose, c3' participates in chain extension, and c5'
commonly bears phosphate. This matches established nucleotide composition, backbone bonding, strand
polarity, and base-pairing principles, so the alternative choices are chemically inconsistent.
4. In a bond-identification exercise, what bond joins a nitrogenous base to its pentose sugar?
A) A peptide bond
B) A phosphodiester bond
C) A disulfide bond
D) An N-glycosidic bond
Correct Answer: An N-glycosidic bond
Rationale: An N-glycosidic bond is correct because the base-sugar connection is an N-glycosidic bond between
the pentose C1' and a ring nitrogen of the base. Peptide bonds join amino acids, phosphodiester bonds join
nucleotides in the backbone, and disulfides link cysteine residues. This matches established nucleotide
composition, backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are
chemically inconsistent.
5. When two nucleotides become covalently linked, what covalent linkage forms the repeating backbone
connection?
A) A peptide bond
B) A 3'-5' phosphodiester bond
C) A hydrogen bond
D) A 2'-2' glycosidic bond
Correct Answer: A 3'-5' phosphodiester bond
Rationale: A 3'-5' phosphodiester bond is correct because adjacent nucleotides are connected by a phosphate
esterified to the 3' oxygen of one sugar and the 5' position of the next. The distractors instead confuse related
components, bond types, orientations, or structural roles. This matches established nucleotide composition,
backbone bonding, strand polarity, and base-pairing principles, so the alternative choices are chemically
inconsistent.
6. For a newly synthesized nucleic-acid chain, what chemical feature gives the strand directionality?
A) Identical phosphate groups at both ends
B) A purine at one end and a pyrimidine at the other
C) Hydrogen bonds between adjacent sugars
D) Chemically distinct 5' and 3' ends
Correct Answer: Chemically distinct 5' and 3' ends
CHEM 210 Module 6 Practice Exam - Page 3
