MMSC491 EXAM 1, EXAM 2, EXAM 3 EXAM QUESTIONS
AND CORRECT VERIFIED SOLUTIONS LATEST UPDATE
THIS YEAR – JUST RELEASED. PRACTICE QUESTIONS
WITH ANSWERS & DETAILED RATIONALES LATEST
2026/2027 UPDATE
Question 1
Which mechanism involves heritable changes in gene expression without changing the
underlying DNA sequence?
A. DNA replication
B. Epigenetic regulation
C. Translation
D. Genetic recombination
Correct Answer: B. Epigenetic regulation
Rationale: Epigenetic regulation changes how genes are expressed without altering the DNA
sequence itself. Common mechanisms include DNA methylation, histone modification, and
changes in chromatin structure.
Question 2
,Which enzyme is primarily responsible for synthesizing a new DNA strand during DNA
replication?
A. Helicase
B. DNA ligase
C. DNA polymerase
D. RNA polymerase
Correct Answer: C. DNA polymerase
Rationale: DNA polymerase adds complementary nucleotides to the growing DNA strand.
Helicase separates the DNA strands, while DNA ligase joins DNA fragments.
Question 3
Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA polymerase
B. Helicase
C. DNA ligase
D. Primase
Correct Answer: B. Helicase
Rationale: Helicase breaks the hydrogen bonds between complementary bases, separating the
two DNA strands and creating the replication fork.
,Question 4
Which nitrogenous base is present in RNA but generally replaces thymine found in DNA?
A. Cytosine
B. Guanine
C. Uracil
D. Adenine
Correct Answer: C. Uracil
Rationale: RNA contains uracil instead of thymine. Uracil pairs with adenine during RNA base
pairing.
Question 5
What is the process by which genetic information in DNA is used to produce RNA?
A. Translation
B. Transcription
C. Replication
D. Recombination
Correct Answer: B. Transcription
, Rationale: During transcription, RNA polymerase uses one DNA strand as a template to produce
an RNA molecule, such as messenger RNA (mRNA).
Question 6
What is the primary role of messenger RNA (mRNA)?
A. Carry amino acids to the ribosome
B. Carry genetic instructions from DNA to the ribosome
C. Form the cell membrane
D. Replicate DNA
Correct Answer: B. Carry genetic instructions from DNA to the ribosome
Rationale: mRNA carries the genetic code transcribed from DNA to the ribosome, where it
serves as a template for protein synthesis.
Question 7
A mutation changes a codon but does not change the amino acid produced. What type of
mutation is this?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Frameshift mutation
AND CORRECT VERIFIED SOLUTIONS LATEST UPDATE
THIS YEAR – JUST RELEASED. PRACTICE QUESTIONS
WITH ANSWERS & DETAILED RATIONALES LATEST
2026/2027 UPDATE
Question 1
Which mechanism involves heritable changes in gene expression without changing the
underlying DNA sequence?
A. DNA replication
B. Epigenetic regulation
C. Translation
D. Genetic recombination
Correct Answer: B. Epigenetic regulation
Rationale: Epigenetic regulation changes how genes are expressed without altering the DNA
sequence itself. Common mechanisms include DNA methylation, histone modification, and
changes in chromatin structure.
Question 2
,Which enzyme is primarily responsible for synthesizing a new DNA strand during DNA
replication?
A. Helicase
B. DNA ligase
C. DNA polymerase
D. RNA polymerase
Correct Answer: C. DNA polymerase
Rationale: DNA polymerase adds complementary nucleotides to the growing DNA strand.
Helicase separates the DNA strands, while DNA ligase joins DNA fragments.
Question 3
Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA polymerase
B. Helicase
C. DNA ligase
D. Primase
Correct Answer: B. Helicase
Rationale: Helicase breaks the hydrogen bonds between complementary bases, separating the
two DNA strands and creating the replication fork.
,Question 4
Which nitrogenous base is present in RNA but generally replaces thymine found in DNA?
A. Cytosine
B. Guanine
C. Uracil
D. Adenine
Correct Answer: C. Uracil
Rationale: RNA contains uracil instead of thymine. Uracil pairs with adenine during RNA base
pairing.
Question 5
What is the process by which genetic information in DNA is used to produce RNA?
A. Translation
B. Transcription
C. Replication
D. Recombination
Correct Answer: B. Transcription
, Rationale: During transcription, RNA polymerase uses one DNA strand as a template to produce
an RNA molecule, such as messenger RNA (mRNA).
Question 6
What is the primary role of messenger RNA (mRNA)?
A. Carry amino acids to the ribosome
B. Carry genetic instructions from DNA to the ribosome
C. Form the cell membrane
D. Replicate DNA
Correct Answer: B. Carry genetic instructions from DNA to the ribosome
Rationale: mRNA carries the genetic code transcribed from DNA to the ribosome, where it
serves as a template for protein synthesis.
Question 7
A mutation changes a codon but does not change the amino acid produced. What type of
mutation is this?
A. Missense mutation
B. Nonsense mutation
C. Silent mutation
D. Frameshift mutation
