C785 Biochemistry Modules 4–6 Assessment 2026 |WGU
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase I
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to separate the
DNA strands.
2. In DNA replication, which strand is synthesized continuously in the 5’ to 3’
direction?
A. Lagging strand
B. Template strand
C. Leading strand
D. Okazaki strand
Answer: C
Rationale: The leading strand is synthesized continuously toward the replication fork.
,3. Which molecule carries the genetic code from the nucleus to the ribosome?
A. tRNA
B. rRNA
C. mRNA
D. snRNA
Answer: C
Rationale: Messenger RNA (mRNA) acts as the intermediary between DNA and protein
synthesis.
4. What is the role of the sigma factor in prokaryotic transcription?
A. It terminates transcription.
B. It catalyzes the formation of peptide bonds.
C. It helps RNA polymerase recognize the promoter sequence.
D. It proofreads the mRNA transcript.
Answer: C
Rationale: Sigma factor is required for the initiation of transcription in bacteria by
directing RNA polymerase to the promoter.
5. Which of the following is a post-transcriptional modification found in
eukaryotes?
A. Addition of a 5’ cap
B. Binding of DNA polymerase
C. Formation of Okazaki fragments
D. Protein folding by chaperones
Answer: A
Rationale: Eukaryotic mRNA undergoes 5’ capping, 3’ polyadenylation, and splicing.
, 6. What occurs during the ‘Splicing’ process of pre-mRNA?
A. Exons are removed and introns are joined.
B. Amino acids are attached to tRNA.
C. Promoters are activated.
D. Introns are removed and exons are joined.
Answer: D
Rationale: Splicing removes non-coding introns and connects coding exons.
7. The ‘Wobble’ hypothesis explains why:
A. Multiple codons can code for the same amino acid.
B. DNA replication is semi-conservative.
C. Mutations always lead to disease.
D. Enzymes lose shape at high temperatures.
Answer: A
Rationale: Wobble refers to the flexibility in base pairing at the third position of the
codon/anticodon.
8. Which type of mutation results in a premature stop codon?
A. Silent mutation
B. Missense mutation
C. Nonsense mutation
D. Frameshift mutation
Answer: C
Rationale: A nonsense mutation changes an amino acid codon into a stop codon,
terminating translation early.
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase I
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to separate the
DNA strands.
2. In DNA replication, which strand is synthesized continuously in the 5’ to 3’
direction?
A. Lagging strand
B. Template strand
C. Leading strand
D. Okazaki strand
Answer: C
Rationale: The leading strand is synthesized continuously toward the replication fork.
,3. Which molecule carries the genetic code from the nucleus to the ribosome?
A. tRNA
B. rRNA
C. mRNA
D. snRNA
Answer: C
Rationale: Messenger RNA (mRNA) acts as the intermediary between DNA and protein
synthesis.
4. What is the role of the sigma factor in prokaryotic transcription?
A. It terminates transcription.
B. It catalyzes the formation of peptide bonds.
C. It helps RNA polymerase recognize the promoter sequence.
D. It proofreads the mRNA transcript.
Answer: C
Rationale: Sigma factor is required for the initiation of transcription in bacteria by
directing RNA polymerase to the promoter.
5. Which of the following is a post-transcriptional modification found in
eukaryotes?
A. Addition of a 5’ cap
B. Binding of DNA polymerase
C. Formation of Okazaki fragments
D. Protein folding by chaperones
Answer: A
Rationale: Eukaryotic mRNA undergoes 5’ capping, 3’ polyadenylation, and splicing.
, 6. What occurs during the ‘Splicing’ process of pre-mRNA?
A. Exons are removed and introns are joined.
B. Amino acids are attached to tRNA.
C. Promoters are activated.
D. Introns are removed and exons are joined.
Answer: D
Rationale: Splicing removes non-coding introns and connects coding exons.
7. The ‘Wobble’ hypothesis explains why:
A. Multiple codons can code for the same amino acid.
B. DNA replication is semi-conservative.
C. Mutations always lead to disease.
D. Enzymes lose shape at high temperatures.
Answer: A
Rationale: Wobble refers to the flexibility in base pairing at the third position of the
codon/anticodon.
8. Which type of mutation results in a premature stop codon?
A. Silent mutation
B. Missense mutation
C. Nonsense mutation
D. Frameshift mutation
Answer: C
Rationale: A nonsense mutation changes an amino acid codon into a stop codon,
terminating translation early.
