BIOL 271/ BIOL271 Module 4 Actual Exam 2026/2027 |
Complete Exam-Style Questions with Detailed Rationales
| Pass Guaranteed – A+ Graded
Q1: Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA polymerase
B. Helicase [CORRECT]
C. Ligase
D. Primase
Correct Answer: B
Rationale: Correct because helicase breaks hydrogen bonds between complementary base
pairs to separate the DNA strands at the replication fork.
---
Q2: During transcription, which strand of DNA is used as the template?
A. Leading strand
B. Lagging strand
C. Template strand [CORRECT]
D. Coding strand
Correct Answer: C
Rationale: Correct because RNA polymerase reads the template strand (3' to 5') to synthesize
mRNA in the 5' to 3' direction.
---
Q3: Which process converts mRNA into a polypeptide chain?
A. Replication
B. Transcription
C. Translation [CORRECT]
D. Transformation
Correct Answer: C
Rationale: Correct because translation occurs at the ribosome, where mRNA codons are
matched with tRNA anticodons to assemble amino acids.
---
Q4: Which type of RNA carries amino acids to the ribosome?
A. mRNA
,B. tRNA [CORRECT]
C. rRNA
D. siRNA
Correct Answer: B
Rationale: Correct because transfer RNA (tRNA) delivers specific amino acids to the ribosome
based on codon-anticodon pairing.
---
Q5: Which nitrogenous base is found in RNA but not DNA?
A. Adenine
B. Guanine
C. Uracil [CORRECT]
D. Thymine
Correct Answer: C
Rationale: Correct because uracil replaces thymine in RNA, pairing with adenine during
transcription and translation.
---
Q6: What is the complementary DNA sequence for 5'-ATCGGA-3'?
A. 5'-TAGCCT-3'
B. 3'-TAGCCT-5' [CORRECT]
C. 5'-UAGCCU-3'
D. 3'-ATCGGA-5'
Correct Answer: B
Rationale: Correct because DNA base pairing is antiparallel and complementary: A-T, T-A, C-G,
G-C.
---
Q7: Which enzyme synthesizes a new DNA strand during replication?
A. DNA polymerase [CORRECT]
B. Helicase
C. Ligase
D. Primase
Correct Answer: A
Rationale: Correct because DNA polymerase adds nucleotides to the growing DNA strand
complementary to the template strand.
, ---
Q8: Which molecule serves as the primary energy currency for DNA replication?
A. NADH
B. ATP [CORRECT]
C. Glucose
D. FADH2
Correct Answer: B
Rationale: Correct because ATP hydrolysis provides energy for helicase, polymerase, and
ligase activities during DNA replication.
---
Q9: Which enzyme seals nicks between Okazaki fragments on the lagging strand?
A. DNA polymerase
B. Helicase
C. Ligase [CORRECT]
D. Primase
Correct Answer: C
Rationale: Correct because DNA ligase forms phosphodiester bonds between Okazaki
fragments, creating a continuous strand.
---
Q10: Which type of RNA is a structural component of the ribosome?
A. mRNA
B. tRNA
C. rRNA [CORRECT]
D. siRNA
Correct Answer: C
Rationale: Correct because ribosomal RNA (rRNA) combines with proteins to form ribosomes,
the site of protein synthesis.
---
Q11: Which enzyme is used to cut DNA at specific nucleotide sequences?
A. DNA ligase
B. Restriction enzyme [CORRECT]
C. DNA polymerase
D. Helicase
Complete Exam-Style Questions with Detailed Rationales
| Pass Guaranteed – A+ Graded
Q1: Which enzyme is responsible for unwinding the DNA double helix during replication?
A. DNA polymerase
B. Helicase [CORRECT]
C. Ligase
D. Primase
Correct Answer: B
Rationale: Correct because helicase breaks hydrogen bonds between complementary base
pairs to separate the DNA strands at the replication fork.
---
Q2: During transcription, which strand of DNA is used as the template?
A. Leading strand
B. Lagging strand
C. Template strand [CORRECT]
D. Coding strand
Correct Answer: C
Rationale: Correct because RNA polymerase reads the template strand (3' to 5') to synthesize
mRNA in the 5' to 3' direction.
---
Q3: Which process converts mRNA into a polypeptide chain?
A. Replication
B. Transcription
C. Translation [CORRECT]
D. Transformation
Correct Answer: C
Rationale: Correct because translation occurs at the ribosome, where mRNA codons are
matched with tRNA anticodons to assemble amino acids.
---
Q4: Which type of RNA carries amino acids to the ribosome?
A. mRNA
,B. tRNA [CORRECT]
C. rRNA
D. siRNA
Correct Answer: B
Rationale: Correct because transfer RNA (tRNA) delivers specific amino acids to the ribosome
based on codon-anticodon pairing.
---
Q5: Which nitrogenous base is found in RNA but not DNA?
A. Adenine
B. Guanine
C. Uracil [CORRECT]
D. Thymine
Correct Answer: C
Rationale: Correct because uracil replaces thymine in RNA, pairing with adenine during
transcription and translation.
---
Q6: What is the complementary DNA sequence for 5'-ATCGGA-3'?
A. 5'-TAGCCT-3'
B. 3'-TAGCCT-5' [CORRECT]
C. 5'-UAGCCU-3'
D. 3'-ATCGGA-5'
Correct Answer: B
Rationale: Correct because DNA base pairing is antiparallel and complementary: A-T, T-A, C-G,
G-C.
---
Q7: Which enzyme synthesizes a new DNA strand during replication?
A. DNA polymerase [CORRECT]
B. Helicase
C. Ligase
D. Primase
Correct Answer: A
Rationale: Correct because DNA polymerase adds nucleotides to the growing DNA strand
complementary to the template strand.
, ---
Q8: Which molecule serves as the primary energy currency for DNA replication?
A. NADH
B. ATP [CORRECT]
C. Glucose
D. FADH2
Correct Answer: B
Rationale: Correct because ATP hydrolysis provides energy for helicase, polymerase, and
ligase activities during DNA replication.
---
Q9: Which enzyme seals nicks between Okazaki fragments on the lagging strand?
A. DNA polymerase
B. Helicase
C. Ligase [CORRECT]
D. Primase
Correct Answer: C
Rationale: Correct because DNA ligase forms phosphodiester bonds between Okazaki
fragments, creating a continuous strand.
---
Q10: Which type of RNA is a structural component of the ribosome?
A. mRNA
B. tRNA
C. rRNA [CORRECT]
D. siRNA
Correct Answer: C
Rationale: Correct because ribosomal RNA (rRNA) combines with proteins to form ribosomes,
the site of protein synthesis.
---
Q11: Which enzyme is used to cut DNA at specific nucleotide sequences?
A. DNA ligase
B. Restriction enzyme [CORRECT]
C. DNA polymerase
D. Helicase
