C785 Biochemistry Module 3: Genetics and Gene Expression 2026
|WGU
1. Which component of a nucleotide is responsible for the ‘backbone’ structure
of DNA along with the phosphate group?
A. Nitrogenous base
B. Amino acid
C. Deoxyribose sugar
D. Hydrogen bond
Answer: C
Rationale: The DNA backbone consists of alternating phosphate groups and deoxyribose
sugar molecules.
2. In a DNA double helix, which nitrogenous base pairs with Cytosine?
A. Adenine
B. Uracil
C. Thymine
D. Guanine
Answer: D
Rationale: Based on Chargaff’s rules, Guanine always pairs with Cytosine via three
hydrogen bonds.
,3. What is the primary enzyme responsible for unwinding the DNA double helix
during replication?
A. DNA Polymerase
B. Ligase
C. Primase
D. Helicase
Answer: D
Rationale: Helicase breaks the hydrogen bonds between bases to ‘unzip’ or unwind the
DNA strands for replication.
4. During DNA replication, in which direction is the new DNA strand
synthesized?
A. 3’ to 5’
B. Left to right
C. 5’ to 3’
D. Amino to carboxyl
Answer: C
Rationale: DNA polymerase can only add nucleotides to the 3’ end of a growing strand,
meaning synthesis occurs in the 5’ to 3’ direction.
5. What are the short fragments of DNA synthesized on the lagging strand
called?
A. Primers
B. Okazaki fragments
C. Introns
D. Exons
Answer: B
Rationale: The lagging strand is synthesized discontinuously in short segments known as
Okazaki fragments.
, 6. Which enzyme joins Okazaki fragments together to create a continuous DNA
strand?
A. DNA Ligase
B. RNA Polymerase
C. Helicase
D. Topoisomerase
Answer: A
Rationale: DNA Ligase acts as the ‘glue’ that seals the nicks between DNA fragments on the
lagging strand.
7. Which molecule serves as the template for translation?
A. tRNA
B. rRNA
C. mRNA
D. DNA
Answer: C
Rationale: Messenger RNA (mRNA) carries the genetic code from the DNA in the nucleus
to the ribosome for protein synthesis.
8. Transcription takes place in which part of the eukaryotic cell?
A. Cytoplasm
B. Nucleus
C. Ribosome
D. Mitochondria
Answer: B
Rationale: In eukaryotes, DNA is housed in the nucleus, which is where mRNA is
transcribed.
|WGU
1. Which component of a nucleotide is responsible for the ‘backbone’ structure
of DNA along with the phosphate group?
A. Nitrogenous base
B. Amino acid
C. Deoxyribose sugar
D. Hydrogen bond
Answer: C
Rationale: The DNA backbone consists of alternating phosphate groups and deoxyribose
sugar molecules.
2. In a DNA double helix, which nitrogenous base pairs with Cytosine?
A. Adenine
B. Uracil
C. Thymine
D. Guanine
Answer: D
Rationale: Based on Chargaff’s rules, Guanine always pairs with Cytosine via three
hydrogen bonds.
,3. What is the primary enzyme responsible for unwinding the DNA double helix
during replication?
A. DNA Polymerase
B. Ligase
C. Primase
D. Helicase
Answer: D
Rationale: Helicase breaks the hydrogen bonds between bases to ‘unzip’ or unwind the
DNA strands for replication.
4. During DNA replication, in which direction is the new DNA strand
synthesized?
A. 3’ to 5’
B. Left to right
C. 5’ to 3’
D. Amino to carboxyl
Answer: C
Rationale: DNA polymerase can only add nucleotides to the 3’ end of a growing strand,
meaning synthesis occurs in the 5’ to 3’ direction.
5. What are the short fragments of DNA synthesized on the lagging strand
called?
A. Primers
B. Okazaki fragments
C. Introns
D. Exons
Answer: B
Rationale: The lagging strand is synthesized discontinuously in short segments known as
Okazaki fragments.
, 6. Which enzyme joins Okazaki fragments together to create a continuous DNA
strand?
A. DNA Ligase
B. RNA Polymerase
C. Helicase
D. Topoisomerase
Answer: A
Rationale: DNA Ligase acts as the ‘glue’ that seals the nicks between DNA fragments on the
lagging strand.
7. Which molecule serves as the template for translation?
A. tRNA
B. rRNA
C. mRNA
D. DNA
Answer: C
Rationale: Messenger RNA (mRNA) carries the genetic code from the DNA in the nucleus
to the ribosome for protein synthesis.
8. Transcription takes place in which part of the eukaryotic cell?
A. Cytoplasm
B. Nucleus
C. Ribosome
D. Mitochondria
Answer: B
Rationale: In eukaryotes, DNA is housed in the nucleus, which is where mRNA is
transcribed.
