C785 Biochemistry - Week 7 Practice Quiz 2026 |WGU
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to unzip the
DNA strands.
2. In which direction is a new DNA strand synthesized?
A. 3’ to 5’
B. Left to right only
C. N-terminus to C-terminus
D. 5’ to 3’
Answer: D
Rationale: DNA Polymerase can only add nucleotides to the 3’ end of a growing strand,
meaning synthesis occurs in the 5’ to 3’ direction.
3. What is the role of Primase in DNA replication?
A. To seal gaps between fragments
B. To remove RNA primers
C. To proofread the DNA sequence
D. To synthesize a short RNA primer to provide a 3’-OH group
Answer: D
,Rationale: DNA Polymerase cannot start a strand from scratch; Primase provides the
necessary RNA starting point.
4. Which fragment type is found on the lagging strand during DNA replication?
A. Transcription units
B. Okazaki fragments
C. Leading fragments
D. Promoter sequences
Answer: B
Rationale: The lagging strand is synthesized discontinuously in short segments called
Okazaki fragments.
5. Which enzyme joins Okazaki fragments together?
A. Topoisomerase
B. DNA Ligase
C. Helicase
D. RNA Polymerase
Answer: B
Rationale: DNA Ligase acts as ‘glue’ by forming phosphodiester bonds between DNA
segments.
6. What is the primary function of DNA Polymerase III?
A. Elongating the new DNA strand
B. Unwinding DNA
C. Replacing RNA primers with DNA
D. Repairing UV damage
Answer: A
Rationale: DNA Polymerase III is the main enzyme responsible for adding nucleotides to
the new DNA strand during replication.
, 7. Which process converts DNA into mRNA?
A. Translation
B. Transcription
C. Replication
D. Transformation
Answer: B
Rationale: Transcription is the process where a DNA template is used to produce a
complementary RNA molecule.
8. Where does transcription occur in a eukaryotic cell?
A. Cytoplasm
B. Ribosome
C. Nucleus
D. Mitochondria
Answer: C
Rationale: In eukaryotes, DNA is stored in the nucleus, so transcription must take place
there before the mRNA moves to the cytoplasm.
9. What is the ‘central dogma’ of molecular biology?
A. Protein -> RNA -> DNA
B. RNA -> DNA -> Protein
C. DNA -> RNA -> Protein
D. DNA -> Protein -> RNA
Answer: C
Rationale: The central dogma describes the flow of genetic information from DNA to RNA
and finally to proteins.
1. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to unzip the
DNA strands.
2. In which direction is a new DNA strand synthesized?
A. 3’ to 5’
B. Left to right only
C. N-terminus to C-terminus
D. 5’ to 3’
Answer: D
Rationale: DNA Polymerase can only add nucleotides to the 3’ end of a growing strand,
meaning synthesis occurs in the 5’ to 3’ direction.
3. What is the role of Primase in DNA replication?
A. To seal gaps between fragments
B. To remove RNA primers
C. To proofread the DNA sequence
D. To synthesize a short RNA primer to provide a 3’-OH group
Answer: D
,Rationale: DNA Polymerase cannot start a strand from scratch; Primase provides the
necessary RNA starting point.
4. Which fragment type is found on the lagging strand during DNA replication?
A. Transcription units
B. Okazaki fragments
C. Leading fragments
D. Promoter sequences
Answer: B
Rationale: The lagging strand is synthesized discontinuously in short segments called
Okazaki fragments.
5. Which enzyme joins Okazaki fragments together?
A. Topoisomerase
B. DNA Ligase
C. Helicase
D. RNA Polymerase
Answer: B
Rationale: DNA Ligase acts as ‘glue’ by forming phosphodiester bonds between DNA
segments.
6. What is the primary function of DNA Polymerase III?
A. Elongating the new DNA strand
B. Unwinding DNA
C. Replacing RNA primers with DNA
D. Repairing UV damage
Answer: A
Rationale: DNA Polymerase III is the main enzyme responsible for adding nucleotides to
the new DNA strand during replication.
, 7. Which process converts DNA into mRNA?
A. Translation
B. Transcription
C. Replication
D. Transformation
Answer: B
Rationale: Transcription is the process where a DNA template is used to produce a
complementary RNA molecule.
8. Where does transcription occur in a eukaryotic cell?
A. Cytoplasm
B. Ribosome
C. Nucleus
D. Mitochondria
Answer: C
Rationale: In eukaryotes, DNA is stored in the nucleus, so transcription must take place
there before the mRNA moves to the cytoplasm.
9. What is the ‘central dogma’ of molecular biology?
A. Protein -> RNA -> DNA
B. RNA -> DNA -> Protein
C. DNA -> RNA -> Protein
D. DNA -> Protein -> RNA
Answer: C
Rationale: The central dogma describes the flow of genetic information from DNA to RNA
and finally to proteins.
