WGU C785 Final Exam 2024 – Complete Questions and
Correct Answers | Verified Edition
Question 1:
Which process converts mRNA into a polypeptide chain?
A) Replication
B) Transcription
C) Translation
D) Mutation
Correct Answer: C
Rationale: Translation is the process where ribosomes read the mRNA sequence and
synthesize a polypeptide chain using tRNA to match codons with amino acids. Replication (A)
duplicates DNA. Transcription (B) synthesizes mRNA from DNA. Mutation (D) alters DNA
sequence but does not involve protein synthesis.
Question 2:
During DNA replication, which enzyme is responsible for adding nucleotides to the growing
strand?
A) Helicase
B) Primase
C) DNA polymerase
D) Ligase
Correct Answer: C
Rationale: DNA polymerase adds nucleotides to the 3' end of the primer, synthesizing the new
strand in the 5' to 3' direction. Helicase (A) unwinds the double helix. Primase (B) synthesizes
RNA primers. Ligase (D) joins Okazaki fragments on the lagging strand.
Question 3:
What is the role of RNA polymerase in transcription?
A) To unwind DNA
B) To synthesize mRNA from the DNA template
C) To add amino acids to proteins
D) To repair DNA mismatches
Correct Answer: B
,Rationale: RNA polymerase binds to the promoter and synthesizes mRNA complementary to
the DNA template strand during transcription. Unwinding (A) is helicase. Amino acids (C) is
translation. Mismatches (D) is proofreading in replication.
Question 4:
In the central dogma of molecular biology, the flow of genetic information is:
A) Protein to RNA to DNA
B) DNA to RNA to protein
C) RNA to DNA to protein
D) Protein to DNA to RNA
Correct Answer: B
Rationale: The central dogma describes information flow from DNA (replication/transcription) to
RNA to protein (translation). Reverse flows (A, C, D) do not occur in standard cellular
processes.
Question 5:
Which structure of tRNA is responsible for recognizing the mRNA codon?
A) Acceptor stem
B) Anticodon loop
C) D-loop
D) TψC loop
Correct Answer: B
Rationale: The anticodon loop base-pairs with the mRNA codon during translation to ensure
correct amino acid placement. Acceptor stem (A) binds amino acid. D-loop (C) and TψC (D) are
structural, not recognition.
Question 6:
Semiconservative replication means:
A) Each new DNA molecule has one old and one new strand
B) Both strands are entirely new
C) The original DNA is conserved intact
D) Replication occurs without enzymes
Correct Answer: A
Rationale: Semiconservative replication, proven by Meselson-Stahl, results in hybrid DNA with
one parental and one daughter strand. Conservative (C) keeps original intact. Dispersive (B)
mixes old/new. No enzymes (D) impossible.
,Question 7:
The leading strand in DNA replication is synthesized:
A) Discontinuously
B) Continuously in the 5' to 3' direction
C) In the 3' to 5' direction
D) Without primers
Correct Answer: B
Rationale: The leading strand is synthesized continuously toward the replication fork in the 5' to
3' direction by DNA polymerase. Lagging (A) discontinuous Okazaki. Opposite direction (C) not
possible. Primers needed (D) false.
Question 8:
Which molecule serves as the template for mRNA synthesis?
A) Coding strand
B) Template strand
C) Ribosomal RNA
D) Transfer RNA
Correct Answer: B
Rationale: The template (antisense) strand is transcribed by RNA polymerase to produce
complementary mRNA. Coding (A) has same sequence as mRNA (T/U). rRNA (C) structural.
tRNA (D) translation.
Question 9:
A frameshift mutation is caused by:
A) Base substitution
B) Insertion or deletion of nucleotides not in multiples of three
C) Silent base change
D) Transition only
Correct Answer: B
Rationale: Frameshift mutations shift the reading frame by insertion/deletion not divisible by 3,
altering all downstream codons. Substitution (A) point. Silent (C) no amino acid change.
Transition (D) purine/pyrimidine swap.
Question 10:
The enzyme telomerase adds nucleotides to:
A) The 5' end of the leading strand
B) The 3' end of the lagging strand
, C) mRNA during splicing
D) tRNA during charging
Correct Answer: B
Rationale: Telomerase extends the 3' overhang on the lagging strand to prevent telomere
shortening. Leading (A) continuous. Splicing (C) RNA. Charging (D) aminoacyl-tRNA
synthetase.
Question 11:
In prokaryotes, transcription and translation occur:
A) In separate cellular compartments
B) Simultaneously in the cytoplasm
C) Only after mRNA export
D) During G2 phase
Correct Answer: B
Rationale: Prokaryotes lack nucleus, so coupled transcription/translation (B) on nascent mRNA.
Eukaryotes separate (A). Export (C) eukaryotic. G2 (D) mitosis.
Question 12:
The wobble hypothesis explains:
A) Flexible base-pairing at the third codon position
B) Strict Watson-Crick pairing only
C) Frameshift errors
D) Stop codon recognition
Correct Answer: A
Rationale: Wobble allows non-standard pairing at 3' end of codon-anticodon, reducing tRNA
need (A). Strict (B) first two positions. Frameshift (C) indels. Stop (D) release factors.
Question 13:
A missense mutation:
A) Changes one amino acid
B) Introduces a stop codon
C) Deletes a codon
D) Duplicates a segment
Correct Answer: A
Correct Answers | Verified Edition
Question 1:
Which process converts mRNA into a polypeptide chain?
A) Replication
B) Transcription
C) Translation
D) Mutation
Correct Answer: C
Rationale: Translation is the process where ribosomes read the mRNA sequence and
synthesize a polypeptide chain using tRNA to match codons with amino acids. Replication (A)
duplicates DNA. Transcription (B) synthesizes mRNA from DNA. Mutation (D) alters DNA
sequence but does not involve protein synthesis.
Question 2:
During DNA replication, which enzyme is responsible for adding nucleotides to the growing
strand?
A) Helicase
B) Primase
C) DNA polymerase
D) Ligase
Correct Answer: C
Rationale: DNA polymerase adds nucleotides to the 3' end of the primer, synthesizing the new
strand in the 5' to 3' direction. Helicase (A) unwinds the double helix. Primase (B) synthesizes
RNA primers. Ligase (D) joins Okazaki fragments on the lagging strand.
Question 3:
What is the role of RNA polymerase in transcription?
A) To unwind DNA
B) To synthesize mRNA from the DNA template
C) To add amino acids to proteins
D) To repair DNA mismatches
Correct Answer: B
,Rationale: RNA polymerase binds to the promoter and synthesizes mRNA complementary to
the DNA template strand during transcription. Unwinding (A) is helicase. Amino acids (C) is
translation. Mismatches (D) is proofreading in replication.
Question 4:
In the central dogma of molecular biology, the flow of genetic information is:
A) Protein to RNA to DNA
B) DNA to RNA to protein
C) RNA to DNA to protein
D) Protein to DNA to RNA
Correct Answer: B
Rationale: The central dogma describes information flow from DNA (replication/transcription) to
RNA to protein (translation). Reverse flows (A, C, D) do not occur in standard cellular
processes.
Question 5:
Which structure of tRNA is responsible for recognizing the mRNA codon?
A) Acceptor stem
B) Anticodon loop
C) D-loop
D) TψC loop
Correct Answer: B
Rationale: The anticodon loop base-pairs with the mRNA codon during translation to ensure
correct amino acid placement. Acceptor stem (A) binds amino acid. D-loop (C) and TψC (D) are
structural, not recognition.
Question 6:
Semiconservative replication means:
A) Each new DNA molecule has one old and one new strand
B) Both strands are entirely new
C) The original DNA is conserved intact
D) Replication occurs without enzymes
Correct Answer: A
Rationale: Semiconservative replication, proven by Meselson-Stahl, results in hybrid DNA with
one parental and one daughter strand. Conservative (C) keeps original intact. Dispersive (B)
mixes old/new. No enzymes (D) impossible.
,Question 7:
The leading strand in DNA replication is synthesized:
A) Discontinuously
B) Continuously in the 5' to 3' direction
C) In the 3' to 5' direction
D) Without primers
Correct Answer: B
Rationale: The leading strand is synthesized continuously toward the replication fork in the 5' to
3' direction by DNA polymerase. Lagging (A) discontinuous Okazaki. Opposite direction (C) not
possible. Primers needed (D) false.
Question 8:
Which molecule serves as the template for mRNA synthesis?
A) Coding strand
B) Template strand
C) Ribosomal RNA
D) Transfer RNA
Correct Answer: B
Rationale: The template (antisense) strand is transcribed by RNA polymerase to produce
complementary mRNA. Coding (A) has same sequence as mRNA (T/U). rRNA (C) structural.
tRNA (D) translation.
Question 9:
A frameshift mutation is caused by:
A) Base substitution
B) Insertion or deletion of nucleotides not in multiples of three
C) Silent base change
D) Transition only
Correct Answer: B
Rationale: Frameshift mutations shift the reading frame by insertion/deletion not divisible by 3,
altering all downstream codons. Substitution (A) point. Silent (C) no amino acid change.
Transition (D) purine/pyrimidine swap.
Question 10:
The enzyme telomerase adds nucleotides to:
A) The 5' end of the leading strand
B) The 3' end of the lagging strand
, C) mRNA during splicing
D) tRNA during charging
Correct Answer: B
Rationale: Telomerase extends the 3' overhang on the lagging strand to prevent telomere
shortening. Leading (A) continuous. Splicing (C) RNA. Charging (D) aminoacyl-tRNA
synthetase.
Question 11:
In prokaryotes, transcription and translation occur:
A) In separate cellular compartments
B) Simultaneously in the cytoplasm
C) Only after mRNA export
D) During G2 phase
Correct Answer: B
Rationale: Prokaryotes lack nucleus, so coupled transcription/translation (B) on nascent mRNA.
Eukaryotes separate (A). Export (C) eukaryotic. G2 (D) mitosis.
Question 12:
The wobble hypothesis explains:
A) Flexible base-pairing at the third codon position
B) Strict Watson-Crick pairing only
C) Frameshift errors
D) Stop codon recognition
Correct Answer: A
Rationale: Wobble allows non-standard pairing at 3' end of codon-anticodon, reducing tRNA
need (A). Strict (B) first two positions. Frameshift (C) indels. Stop (D) release factors.
Question 13:
A missense mutation:
A) Changes one amino acid
B) Introduces a stop codon
C) Deletes a codon
D) Duplicates a segment
Correct Answer: A
