WGU C785 BIOCHEMISTRY FINAL EXAM 2026/2027 | For
Nursing Complete Answers | Certification Q&A | Pass
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Section 1: DNA Structure, Replication & Gene Expression (Q1-15)
Q1
Which nitrogenous base pairs with adenine in DNA through two hydrogen bonds?
A. Cytosine
B. Guanine
C. Thymine [CORRECT]
D. Uracil
Rationale: In DNA, adenine pairs with thymine via two hydrogen bonds. Guanine pairs
with cytosine via three hydrogen bonds. Uracil is found in RNA, not DNA. DNA Structure,
Replication & Gene Expression
Correct Answer: C
Q2
A nursing student is reviewing the enzymes involved in DNA replication. Which enzyme
is responsible for unwinding the double helix by breaking hydrogen bonds between base
pairs?
A. DNA polymerase
B. DNA ligase
C. Helicase [CORRECT]
D. Primase
,Rationale: Helicase unwinds the DNA double helix by breaking hydrogen bonds. DNA
polymerase synthesizes new DNA strands, DNA ligase joins Okazaki fragments, and
primase synthesizes RNA primers. DNA Structure, Replication & Gene Expression
Correct Answer: C
Q3
During DNA replication, which enzyme synthesizes the new DNA strand by adding
nucleotides in the 5' to 3' direction?
A. Helicase
B. DNA polymerase [CORRECT]
C. RNA polymerase
D. Topoisomerase
Rationale: DNA polymerase synthesizes new DNA in the 5' to 3' direction only. RNA
polymerase is used in transcription, helicase unwinds DNA, and topoisomerase relieves
supercoiling stress. DNA Structure, Replication & Gene Expression
Correct Answer: B
Q4
A client has a genetic mutation causing sickle cell disease. Using the codon chart, the
normal DNA template strand reads 3'-CAC-5', producing mRNA codon 5'-GUG-3' for
valine instead of the normal glutamic acid. Which type of mutation is present if the
original DNA coding strand was 3'-GTG-5' (template 3'-CAC-5') changed to template
3'-CTC-5'?
A. Silent mutation
B. Missense mutation [CORRECT]
C. Nonsense mutation
D. Frameshift mutation
Rationale: A missense mutation changes a single amino acid (glutamic acid to valine at
position 6 of beta-globin). Silent mutations produce the same amino acid, nonsense
,mutations create a stop codon, and frameshift mutations shift the reading frame. DNA
Structure, Replication & Gene Expression
Correct Answer: B
Q5
Which RNA molecule carries amino acids to the ribosome during translation?
A. mRNA
B. rRNA
C. tRNA [CORRECT]
D. snRNA
Rationale: tRNA (transfer RNA) carries specific amino acids to the ribosome and has an
anticodon that pairs with mRNA codons. mRNA carries the genetic code, rRNA forms
ribosomal structure, and snRNA is involved in splicing. DNA Structure, Replication &
Gene Expression
Correct Answer: C
Q6
A nurse is reviewing transcription. Which statement correctly describes this process?
A. DNA is synthesized from an RNA template
B. RNA is synthesized from a DNA template [CORRECT]
C. Proteins are synthesized from an mRNA template
D. DNA is synthesized from a DNA template
Rationale: Transcription is the synthesis of RNA from a DNA template. Translation
synthesizes protein from mRNA, and DNA replication synthesizes DNA from DNA. DNA
Structure, Replication & Gene Expression
Correct Answer: B
, Q7
In eukaryotic cells, which structure removes introns from pre-mRNA before it exits the
nucleus?
A. Ribosome
B. Spliceosome [CORRECT]
C. Nucleolus
D. Proteasome
Rationale: The spliceosome removes introns (non-coding regions) and joins exons
(coding regions) during RNA splicing. Ribosomes perform translation, the nucleolus
produces rRNA, and proteasomes degrade proteins. DNA Structure, Replication & Gene
Expression
Correct Answer: B
Q8
A biochemistry instructor asks students to identify the start codon that initiates
translation. Which mRNA codon is correct?
A. UAA
B. UAG
C. UGA
D. AUG [CORRECT]
Rationale: AUG is the start codon that codes for methionine and initiates translation.
UAA, UAG, and UGA are stop codons that terminate protein synthesis. DNA Structure,
Replication & Gene Expression
Correct Answer: D
Q9
Using a standard codon chart, which amino acid is specified by the mRNA codon
5'-CCU-3'?
A. Glycine
B. Alanine
Nursing Complete Answers | Certification Q&A | Pass
Guaranteed - A+ Graded
Section 1: DNA Structure, Replication & Gene Expression (Q1-15)
Q1
Which nitrogenous base pairs with adenine in DNA through two hydrogen bonds?
A. Cytosine
B. Guanine
C. Thymine [CORRECT]
D. Uracil
Rationale: In DNA, adenine pairs with thymine via two hydrogen bonds. Guanine pairs
with cytosine via three hydrogen bonds. Uracil is found in RNA, not DNA. DNA Structure,
Replication & Gene Expression
Correct Answer: C
Q2
A nursing student is reviewing the enzymes involved in DNA replication. Which enzyme
is responsible for unwinding the double helix by breaking hydrogen bonds between base
pairs?
A. DNA polymerase
B. DNA ligase
C. Helicase [CORRECT]
D. Primase
,Rationale: Helicase unwinds the DNA double helix by breaking hydrogen bonds. DNA
polymerase synthesizes new DNA strands, DNA ligase joins Okazaki fragments, and
primase synthesizes RNA primers. DNA Structure, Replication & Gene Expression
Correct Answer: C
Q3
During DNA replication, which enzyme synthesizes the new DNA strand by adding
nucleotides in the 5' to 3' direction?
A. Helicase
B. DNA polymerase [CORRECT]
C. RNA polymerase
D. Topoisomerase
Rationale: DNA polymerase synthesizes new DNA in the 5' to 3' direction only. RNA
polymerase is used in transcription, helicase unwinds DNA, and topoisomerase relieves
supercoiling stress. DNA Structure, Replication & Gene Expression
Correct Answer: B
Q4
A client has a genetic mutation causing sickle cell disease. Using the codon chart, the
normal DNA template strand reads 3'-CAC-5', producing mRNA codon 5'-GUG-3' for
valine instead of the normal glutamic acid. Which type of mutation is present if the
original DNA coding strand was 3'-GTG-5' (template 3'-CAC-5') changed to template
3'-CTC-5'?
A. Silent mutation
B. Missense mutation [CORRECT]
C. Nonsense mutation
D. Frameshift mutation
Rationale: A missense mutation changes a single amino acid (glutamic acid to valine at
position 6 of beta-globin). Silent mutations produce the same amino acid, nonsense
,mutations create a stop codon, and frameshift mutations shift the reading frame. DNA
Structure, Replication & Gene Expression
Correct Answer: B
Q5
Which RNA molecule carries amino acids to the ribosome during translation?
A. mRNA
B. rRNA
C. tRNA [CORRECT]
D. snRNA
Rationale: tRNA (transfer RNA) carries specific amino acids to the ribosome and has an
anticodon that pairs with mRNA codons. mRNA carries the genetic code, rRNA forms
ribosomal structure, and snRNA is involved in splicing. DNA Structure, Replication &
Gene Expression
Correct Answer: C
Q6
A nurse is reviewing transcription. Which statement correctly describes this process?
A. DNA is synthesized from an RNA template
B. RNA is synthesized from a DNA template [CORRECT]
C. Proteins are synthesized from an mRNA template
D. DNA is synthesized from a DNA template
Rationale: Transcription is the synthesis of RNA from a DNA template. Translation
synthesizes protein from mRNA, and DNA replication synthesizes DNA from DNA. DNA
Structure, Replication & Gene Expression
Correct Answer: B
, Q7
In eukaryotic cells, which structure removes introns from pre-mRNA before it exits the
nucleus?
A. Ribosome
B. Spliceosome [CORRECT]
C. Nucleolus
D. Proteasome
Rationale: The spliceosome removes introns (non-coding regions) and joins exons
(coding regions) during RNA splicing. Ribosomes perform translation, the nucleolus
produces rRNA, and proteasomes degrade proteins. DNA Structure, Replication & Gene
Expression
Correct Answer: B
Q8
A biochemistry instructor asks students to identify the start codon that initiates
translation. Which mRNA codon is correct?
A. UAA
B. UAG
C. UGA
D. AUG [CORRECT]
Rationale: AUG is the start codon that codes for methionine and initiates translation.
UAA, UAG, and UGA are stop codons that terminate protein synthesis. DNA Structure,
Replication & Gene Expression
Correct Answer: D
Q9
Using a standard codon chart, which amino acid is specified by the mRNA codon
5'-CCU-3'?
A. Glycine
B. Alanine
