BIOL 101 Week 5 Quiz V1 | BIOL 101 Principles of
Biology | Actual Q&A with Rationale (BIOL101
Week 5 Quiz) | Liberty University
1. Which of the following enzymes is responsible for unwinding the DNA double helix at the
replication fork?
A. DNA Ligase
B. DNA Polymerase
C. Topoisomerase
D. Helicase
Correct Answer: D
Explanation: Helicase is the specific enzyme that breaks the hydrogen bonds between
complementary nitrogenous bases to separate the strands. This separation creates the
replication fork where the synthesis of new DNA occurs. Without this unwinding action, the
polymerase would not be able to access the template strands.
2. In the central dogma of molecular biology, what process describes the synthesis of RNA
from a DNA template?
A. Translation
B. Replication
C. Transcription
,D. Transformation
Correct Answer: C
Explanation: Transcription is the phase where information from a gene is transferred into
a messenger RNA molecule. This occurs within the nucleus of eukaryotic cells before the
message is transported to the cytoplasm. It is catalyzed by RNA polymerase which reads
the DNA template in a 3’ to 5’ direction.
3. Which molecule serves as the physical link between the mRNA codon and the specific
amino acid during translation?
A. tRNA
B. snRNA
C. rRNA
D. siRNA
Correct Answer: A
Explanation: Transfer RNA (tRNA) contains an anticodon that is complementary to the
mRNA codon. Each tRNA molecule is chemically bonded to a specific amino acid by an
aminoacyl-tRNA synthetase. This ensuring that the genetic code is accurately translated
into the correct protein sequence.
4. Chargaff’s rules state that in any sample of DNA, the amount of adenine is approximately
equal to the amount of thymine. What is the reason for this?
A. Adenine and thymine are both purines.
, B. Adenine and thymine form base pairs via two hydrogen bonds.
C. Adenine and thymine are both pyrimidines.
D. Adenine and thymine are synthesized in the same metabolic pathway.
Correct Answer: B
Explanation: The structural complementarity between adenine and thymine allows them
to pair specifically with two hydrogen bonds. This specific pairing ensures that the distance
between the two sugar-phosphate backbones remains constant. Consequently, the total
amount of these two bases must remain equivalent in a double-stranded DNA molecule.
5. During DNA replication, the lagging strand is synthesized in short segments known as:
A. Watson fragments
B. Crick segments
C. Okazaki fragments
D. Chargaff units
Correct Answer: C
Explanation: Because DNA polymerase can only synthesize DNA in the 5’ to 3’ direction,
the lagging strand must be synthesized discontinuously. These short sections are later
joined together by DNA ligase to form a continuous strand. This mechanism allows the
replication fork to move in one direction while both strands are replicated simultaneously.
Biology | Actual Q&A with Rationale (BIOL101
Week 5 Quiz) | Liberty University
1. Which of the following enzymes is responsible for unwinding the DNA double helix at the
replication fork?
A. DNA Ligase
B. DNA Polymerase
C. Topoisomerase
D. Helicase
Correct Answer: D
Explanation: Helicase is the specific enzyme that breaks the hydrogen bonds between
complementary nitrogenous bases to separate the strands. This separation creates the
replication fork where the synthesis of new DNA occurs. Without this unwinding action, the
polymerase would not be able to access the template strands.
2. In the central dogma of molecular biology, what process describes the synthesis of RNA
from a DNA template?
A. Translation
B. Replication
C. Transcription
,D. Transformation
Correct Answer: C
Explanation: Transcription is the phase where information from a gene is transferred into
a messenger RNA molecule. This occurs within the nucleus of eukaryotic cells before the
message is transported to the cytoplasm. It is catalyzed by RNA polymerase which reads
the DNA template in a 3’ to 5’ direction.
3. Which molecule serves as the physical link between the mRNA codon and the specific
amino acid during translation?
A. tRNA
B. snRNA
C. rRNA
D. siRNA
Correct Answer: A
Explanation: Transfer RNA (tRNA) contains an anticodon that is complementary to the
mRNA codon. Each tRNA molecule is chemically bonded to a specific amino acid by an
aminoacyl-tRNA synthetase. This ensuring that the genetic code is accurately translated
into the correct protein sequence.
4. Chargaff’s rules state that in any sample of DNA, the amount of adenine is approximately
equal to the amount of thymine. What is the reason for this?
A. Adenine and thymine are both purines.
, B. Adenine and thymine form base pairs via two hydrogen bonds.
C. Adenine and thymine are both pyrimidines.
D. Adenine and thymine are synthesized in the same metabolic pathway.
Correct Answer: B
Explanation: The structural complementarity between adenine and thymine allows them
to pair specifically with two hydrogen bonds. This specific pairing ensures that the distance
between the two sugar-phosphate backbones remains constant. Consequently, the total
amount of these two bases must remain equivalent in a double-stranded DNA molecule.
5. During DNA replication, the lagging strand is synthesized in short segments known as:
A. Watson fragments
B. Crick segments
C. Okazaki fragments
D. Chargaff units
Correct Answer: C
Explanation: Because DNA polymerase can only synthesize DNA in the 5’ to 3’ direction,
the lagging strand must be synthesized discontinuously. These short sections are later
joined together by DNA ligase to form a continuous strand. This mechanism allows the
replication fork to move in one direction while both strands are replicated simultaneously.
