BIOL 101 Quiz 4 V1 | BIOL 101 Principles of
Biology | Actual Q&A with Rationale (BIOL101 Quiz
4) | Liberty University
1. Which scientist’s X-ray diffraction images were instrumental in determining the double-
helix structure of DNA?
A. James Watson
B. Rosalind Franklin
C. Francis Crick
D. Gregor Mendel
Correct Answer: B
Explanation: Rosalind Franklin produced the high-resolution X-ray diffraction images of
DNA, known as Photo 51, which revealed the helical nature of the molecule. Her data
provided the critical evidence that Watson and Crick used to build their structural model.
This contribution remained undervalued for years but is now recognized as a cornerstone
of molecular biology.
2. In DNA replication, which enzyme is responsible for unwinding the double helix at the
replication fork?
A. Primase
B. DNA Polymerase
,C. Ligase
D. Helicase
Correct Answer: D
Explanation: Helicase functions by breaking the hydrogen bonds between the nitrogenous
base pairs to separate the two DNA strands. This process creates the replication fork where
other enzymes can access the template strands. Without helicase, the DNA molecule would
remain tightly coiled and inaccessible for copying.
3. What is the primary product of the process known as transcription?
A. A protein chain
B. A double-stranded DNA molecule
C. A tRNA molecule
D. An mRNA molecule
Correct Answer: D
Explanation: Transcription is the stage of gene expression where a specific segment of
DNA is copied into messenger RNA (mRNA) by RNA polymerase. This mRNA serves as a
temporary transcript that carries genetic information from the nucleus to the cytoplasm for
translation. It is a vital step in the flow of information described by the Central Dogma of
biology.
, 4. A codon consists of how many consecutive nucleotides on an mRNA strand?
A. Three
B. Two
C. One
D. Four
Correct Answer: A
Explanation: The genetic code is read in groups of three nucleotides, each group forming a
codon that specifies a single amino acid. This triplet code allows for 64 possible
combinations, which is more than enough to code for the 20 standard amino acids. The
consistency of this triplet code across almost all life forms suggests a common evolutionary
origin.
5. Which type of mutation results in the substitution of one amino acid for another in the
resulting protein?
A. Missense mutation
B. Silent mutation
C. Nonsense mutation
D. Frameshift mutation
Correct Answer: A
Biology | Actual Q&A with Rationale (BIOL101 Quiz
4) | Liberty University
1. Which scientist’s X-ray diffraction images were instrumental in determining the double-
helix structure of DNA?
A. James Watson
B. Rosalind Franklin
C. Francis Crick
D. Gregor Mendel
Correct Answer: B
Explanation: Rosalind Franklin produced the high-resolution X-ray diffraction images of
DNA, known as Photo 51, which revealed the helical nature of the molecule. Her data
provided the critical evidence that Watson and Crick used to build their structural model.
This contribution remained undervalued for years but is now recognized as a cornerstone
of molecular biology.
2. In DNA replication, which enzyme is responsible for unwinding the double helix at the
replication fork?
A. Primase
B. DNA Polymerase
,C. Ligase
D. Helicase
Correct Answer: D
Explanation: Helicase functions by breaking the hydrogen bonds between the nitrogenous
base pairs to separate the two DNA strands. This process creates the replication fork where
other enzymes can access the template strands. Without helicase, the DNA molecule would
remain tightly coiled and inaccessible for copying.
3. What is the primary product of the process known as transcription?
A. A protein chain
B. A double-stranded DNA molecule
C. A tRNA molecule
D. An mRNA molecule
Correct Answer: D
Explanation: Transcription is the stage of gene expression where a specific segment of
DNA is copied into messenger RNA (mRNA) by RNA polymerase. This mRNA serves as a
temporary transcript that carries genetic information from the nucleus to the cytoplasm for
translation. It is a vital step in the flow of information described by the Central Dogma of
biology.
, 4. A codon consists of how many consecutive nucleotides on an mRNA strand?
A. Three
B. Two
C. One
D. Four
Correct Answer: A
Explanation: The genetic code is read in groups of three nucleotides, each group forming a
codon that specifies a single amino acid. This triplet code allows for 64 possible
combinations, which is more than enough to code for the 20 standard amino acids. The
consistency of this triplet code across almost all life forms suggests a common evolutionary
origin.
5. Which type of mutation results in the substitution of one amino acid for another in the
resulting protein?
A. Missense mutation
B. Silent mutation
C. Nonsense mutation
D. Frameshift mutation
Correct Answer: A
