BioChem 210 Exam Module 7 Questions and Ansẉers update

BioChem 210 Exam Module 7
Questions and Ansẉers
2026\2027 update


1. A nucleotide is composed of which three components?
A) A nitrogenous base, a pentose sugar, and a phosphate group
B) A nitrogenous base, a hexose sugar, and an amino acid
C) A fatty acid, glycerol, and a phosphate group
D) An amino acid, a ribose sugar, and a nitrogenous base
Answer: A


2. Which of the following are the purine bases found in DNA and
RNA?
A) Cytosine and Thymine
B) Uracil and Cytosine
C) Adenine and Guanine
D) Adenine and Thymine
Answer: C


3. Which base is found in RNA but replaces Thymine in DNA?
A) Guanine
B) Cytosine
C) Adenine

,D) Uracil
Answer: D


4. What is the primary structural difference between the sugar in
RNA and the sugar in DNA?
A) DNA has a 2'-hydroxyl group; RNA does not.
B) RNA has a 2'-hydroxyl group; DNA does not.
C) DNA contains a 6-carbon sugar; RNA contains a 5-carbon sugar.
D) RNA contains deoxyribose; DNA contains ribose.
Answer: B


5. The linkage connecting adjacent nucleotides in a single strand of
DNA is called a:
A) Peptide bond
B) Glycosidic bond
C) Phosphodiester bond
D) Ester bond
Answer: C


6. In a standard DNA double helix, the two strands run in opposite
directions. This is referred to as:
A) Parallel
B) Antiparallel
C) Bidirectional
D) Unidirectional
Answer: B

, 7. Which of the following base pairs is stabilized by three hydrogen
bonds?
A) Adenine - Thymine
B) Adenine - Uracil
C) Guanine - Cytosine
D) Guanine - Thymine
Answer: C


8. The classical B-form DNA double helix makes one complete turn
every:
A) 3.4 base pairs
B) 10 base pairs
C) 20 base pairs
D) 34 base pairs
Answer: B (Note: It is 3.4 nm per turn, with 10 base pairs per turn)


9. The melting temperature (Tm) of a DNA molecule is the
temperature at which:
A) DNA is synthesized.
B) 50% of the double-stranded DNA is denatured into single strands.
C) DNA is completely degraded.
D) DNA forms a triple helix.
Answer: B