PCB3023C Exam 3: Cell Biology Comprehensive Test 2026 |FGCU
1. Which enzyme is responsible for synthesizing RNA by reading a DNA template
during transcription?
A. DNA Polymerase
B. RNA Polymerase
C. Reverse Transcriptase
D. Helicase
Answer: B
Rationale: RNA polymerase is the primary enzyme that catalyzes the synthesis of RNA
from a DNA template.
2. In eukaryotic cells, where does the process of transcription primarily occur?
A. Nucleus
B. Ribosome
C. Cytoplasm
D. Mitochondria
Answer: A
Rationale: In eukaryotes, DNA is contained within the nucleus, so transcription occurs
there before mRNA is exported.
3. What is the function of the sigma factor in prokaryotic transcription?
A. To unwind the DNA double helix
B. To terminate transcription
C. To catalyze the addition of poly-A tails
D. To recognize and bind to the promoter sequence
Answer: D
,Rationale: The sigma factor is a subunit of bacterial RNA polymerase that enables specific
binding to gene promoters.
4. Which modification is added to the 5’ end of a eukaryotic pre-mRNA?
A. Poly-A tail
B. 7-methylguanosine cap
C. Intron
D. Exon
Answer: B
Rationale: The 5’ cap (7-methylguanosine) protects mRNA from degradation and assists in
ribosome binding.
5. Splicing involves the removal of ______ and the joining of ______.
A. Introns; Exons
B. Promoters; Enhancers
C. Exons; Introns
D. Codons; Anticodons
Answer: A
Rationale: Introns are non-coding sequences removed during splicing, while exons are the
sequences that remain in the mature mRNA.
6. Which molecule carries amino acids to the ribosome during translation?
A. mRNA
B. rRNA
C. tRNA
D. snRNA
Answer: C
Rationale: Transfer RNA (tRNA) acts as an adapter, matching specific amino acids to
codons on the mRNA.
, 7. The wobble hypothesis explains why:
A. DNA replication is semi-discontinuous
B. Transcription is slower than translation
C. Ribosomes can move backwards
D. Multiple codons can code for a single amino acid
Answer: D
Rationale: Wobble base pairing allows a single tRNA to recognize more than one codon,
contributing to the degeneracy of the genetic code.
8. During translation elongation, where does the incoming charged tRNA bind
first in the ribosome?
A. P site
B. E site
C. A site
D. Exit tunnel
Answer: C
Rationale: The A (aminoacyl) site is the entry point for new charged tRNAs.
9. What serves as the ‘start’ codon for most protein synthesis?
A. UAA
B. AUG
C. UGA
D. UAG
Answer: B
Rationale: AUG codes for Methionine and signifies the beginning of the translation process.
1. Which enzyme is responsible for synthesizing RNA by reading a DNA template
during transcription?
A. DNA Polymerase
B. RNA Polymerase
C. Reverse Transcriptase
D. Helicase
Answer: B
Rationale: RNA polymerase is the primary enzyme that catalyzes the synthesis of RNA
from a DNA template.
2. In eukaryotic cells, where does the process of transcription primarily occur?
A. Nucleus
B. Ribosome
C. Cytoplasm
D. Mitochondria
Answer: A
Rationale: In eukaryotes, DNA is contained within the nucleus, so transcription occurs
there before mRNA is exported.
3. What is the function of the sigma factor in prokaryotic transcription?
A. To unwind the DNA double helix
B. To terminate transcription
C. To catalyze the addition of poly-A tails
D. To recognize and bind to the promoter sequence
Answer: D
,Rationale: The sigma factor is a subunit of bacterial RNA polymerase that enables specific
binding to gene promoters.
4. Which modification is added to the 5’ end of a eukaryotic pre-mRNA?
A. Poly-A tail
B. 7-methylguanosine cap
C. Intron
D. Exon
Answer: B
Rationale: The 5’ cap (7-methylguanosine) protects mRNA from degradation and assists in
ribosome binding.
5. Splicing involves the removal of ______ and the joining of ______.
A. Introns; Exons
B. Promoters; Enhancers
C. Exons; Introns
D. Codons; Anticodons
Answer: A
Rationale: Introns are non-coding sequences removed during splicing, while exons are the
sequences that remain in the mature mRNA.
6. Which molecule carries amino acids to the ribosome during translation?
A. mRNA
B. rRNA
C. tRNA
D. snRNA
Answer: C
Rationale: Transfer RNA (tRNA) acts as an adapter, matching specific amino acids to
codons on the mRNA.
, 7. The wobble hypothesis explains why:
A. DNA replication is semi-discontinuous
B. Transcription is slower than translation
C. Ribosomes can move backwards
D. Multiple codons can code for a single amino acid
Answer: D
Rationale: Wobble base pairing allows a single tRNA to recognize more than one codon,
contributing to the degeneracy of the genetic code.
8. During translation elongation, where does the incoming charged tRNA bind
first in the ribosome?
A. P site
B. E site
C. A site
D. Exit tunnel
Answer: C
Rationale: The A (aminoacyl) site is the entry point for new charged tRNAs.
9. What serves as the ‘start’ codon for most protein synthesis?
A. UAA
B. AUG
C. UGA
D. UAG
Answer: B
Rationale: AUG codes for Methionine and signifies the beginning of the translation process.
