PORTAGE LEARNING CHEM 210 MODULE 6 PROBLEM
SET QUESTIONS WITH ANSWERS AND EXPLANATIONS
Question 1.
In the context of this module, what is the most accurate description of RNA 2-prime
hydroxyl?
A. The 2-prime hydroxyl of RNA increases its chemical reactivity and contributes to RNA
being less stable to base-catalyzed hydrolysis than DNA.
B. Polymerases extend nucleic-acid chains by adding nucleotides to a 3-prime hydroxyl, so
the new strand grows 5-prime to 3-prime.
C. Transcription copies information from a DNA template into RNA.
D. Most cellular RNA molecules consist of a single covalent strand that can fold back on
itself to form local secondary structure.
Correct Answer: A. The 2-prime hydroxyl of RNA increases its chemical reactivity
and contributes to RNA being less stable to base-catalyzed hydrolysis than DNA.
Explanation: The defining feature is that The 2-prime hydroxyl of RNA increases its
chemical reactivity and contributes to RNA being less stable to base-catalyzed hydrolysis
than DNA. That definition directly matches the term named in the stem. By contrast,
transcription refers to a different idea: Transcription copies information from a DNA
template into RNA. Keeping these definitions separate helps prevent errors when the same
concepts appear in biochemical structures or pathways.
Question 2.
A student encounters this situation: Adenosine formed from adenine plus ribose. Which
term should the student select?
A. nucleic-acid denaturation
B. Chargaff rule
C. phosphodiester bond
D. nucleoside
Correct Answer: D. nucleoside
Explanation: The key point is that the clue points to nucleoside. A nucleoside contains a
nitrogenous base linked to a pentose sugar but no phosphate group. The example given -
Adenosine formed from adenine plus ribose. - is a direct application of that definition. The
alternative terms describe different structures, processes, or roles and therefore do not fit
the clue as closely.
,Question 3.
Which choice gives the clearest biochemical description of RNA structural and catalytic
roles?
A. Adenine is a purine base found in both DNA and RNA and normally pairs with thymine in
DNA or uracil in RNA.
B. A nucleic acid is a polymer of nucleotide residues that stores, transmits, or helps
express biological information.
C. RNA can fold into complex structures and some RNAs participate directly in catalysis as
ribozymes.
D. In ordinary double-stranded DNA, the amount of adenine equals thymine and the
amount of guanine equals cytosine.
Correct Answer: C. RNA can fold into complex structures and some RNAs
participate directly in catalysis as ribozymes.
Explanation: The defining feature is that RNA can fold into complex structures and some
RNAs participate directly in catalysis as ribozymes. That definition directly matches the
term named in the stem. By contrast, adenine refers to a different idea: Adenine is a
purine base found in both DNA and RNA and normally pairs with thymine in DNA or uracil
in RNA. Keeping these definitions separate helps prevent errors when the same concepts
appear in biochemical structures or pathways.
Question 4.
A student is distinguishing transcription from DNA. Which statement correctly describes
transcription?
A. Adenine and thymine form a standard DNA base pair stabilized by two hydrogen bonds.
B. Transcription copies information from a DNA template into RNA.
C. RNA is usually a single-stranded ribonucleotide polymer involved in information
transfer, structure, regulation, and catalysis.
D. DNA is usually a double-stranded polymer of deoxyribonucleotides that serves as
long-term genetic information storage.
Correct Answer: B. Transcription copies information from a DNA template into
RNA.
Explanation: The underlying principle is that transcription should be defined as follows:
Transcription copies information from a DNA template into RNA. This differs from DNA,
which is described by a separate set of properties. The distinction matters because
substituting one term for the other can change the predicted structure, location, or
biochemical outcome. The correct option therefore preserves the specific meaning of
transcription.
,Question 5.
A learner wants an example of cytosine. Which choice is best?
A. The C in a G-C base pair.
B. The T base paired with adenine in double-stranded DNA.
C. The G in a G-C base pair.
D. Comparing T and U structures and identifying the methyl group on thymine.
Correct Answer: A. The C in a G-C base pair.
Explanation: The correct interpretation is that The C in a G-C base pair. is a
representative example of cytosine. Cytosine is a pyrimidine base found in both DNA and
RNA and normally pairs with guanine. The other options were drawn from related module
concepts, but each illustrates a different biochemical feature. Matching the defining
feature to the example is the most reliable way to solve this type of problem.
Question 6.
A student encounters this situation: RNA polymerase producing an RNA transcript from a
gene. Which term should the student select?
A. phosphate group in nucleotides
B. pentose sugar
C. transcription
D. DNA
Correct Answer: C. transcription
Explanation: The most important distinction is that the clue points to transcription.
Transcription copies information from a DNA template into RNA. The example given - RNA
polymerase producing an RNA transcript from a gene. - is a direct application of that
definition. The alternative terms describe different structures, processes, or roles and
therefore do not fit the clue as closely.
Question 7.
Which option most accurately defines nucleotide?
A. Messenger RNA carries coding information that ribosomes read to direct protein
synthesis.
B. A nucleotide contains a nitrogenous base, a pentose sugar, and one or more phosphate
groups.
C. The 3-prime end of a nucleic-acid strand commonly has a free 3-prime hydroxyl group
available for extension.
D. The phosphate portion of a nucleotide contributes negative charge and participates in
phosphodiester bond formation.
Correct Answer: B. A nucleotide contains a nitrogenous base, a pentose sugar,
and one or more phosphate groups.
Explanation: The defining feature is that A nucleotide contains a nitrogenous base, a
pentose sugar, and one or more phosphate groups. That definition directly matches the
, term named in the stem. By contrast, messenger RNA refers to a different idea: Messenger
RNA carries coding information that ribosomes read to direct protein synthesis. Keeping
these definitions separate helps prevent errors when the same concepts appear in
biochemical structures or pathways.
Question 8.
A student encounters this situation: An A on one DNA strand aligned with T on the opposite
strand. Which term should the student select?
A. uracil
B. deoxyribonucleoside triphosphates
C. RNA structural and catalytic roles
D. A-T base pair
Correct Answer: D. A-T base pair
Explanation: The key point is that the clue points to A-T base pair. Adenine and thymine
form a standard DNA base pair stabilized by two hydrogen bonds. The example given - An
A on one DNA strand aligned with T on the opposite strand. - is a direct application of that
definition. The alternative terms describe different structures, processes, or roles and
therefore do not fit the clue as closely.
Question 9.
Which option provides the strongest example of A-T base pair?
A. An A on one DNA strand aligned with T on the opposite strand.
B. An RNA molecule forming an active three-dimensional catalytic structure.
C. A DNA polymerase selecting dGTP opposite a template cytosine.
D. DNA or RNA built from a repeating sugar-phosphate backbone with attached bases.
Correct Answer: A. An A on one DNA strand aligned with T on the opposite
strand.
Explanation: This choice is correct because An A on one DNA strand aligned with T on the
opposite strand. is a representative example of A-T base pair. Adenine and thymine form a
standard DNA base pair stabilized by two hydrogen bonds. The other options were drawn
from related module concepts, but each illustrates a different biochemical feature.
Matching the defining feature to the example is the most reliable way to solve this type of
problem.
SET QUESTIONS WITH ANSWERS AND EXPLANATIONS
Question 1.
In the context of this module, what is the most accurate description of RNA 2-prime
hydroxyl?
A. The 2-prime hydroxyl of RNA increases its chemical reactivity and contributes to RNA
being less stable to base-catalyzed hydrolysis than DNA.
B. Polymerases extend nucleic-acid chains by adding nucleotides to a 3-prime hydroxyl, so
the new strand grows 5-prime to 3-prime.
C. Transcription copies information from a DNA template into RNA.
D. Most cellular RNA molecules consist of a single covalent strand that can fold back on
itself to form local secondary structure.
Correct Answer: A. The 2-prime hydroxyl of RNA increases its chemical reactivity
and contributes to RNA being less stable to base-catalyzed hydrolysis than DNA.
Explanation: The defining feature is that The 2-prime hydroxyl of RNA increases its
chemical reactivity and contributes to RNA being less stable to base-catalyzed hydrolysis
than DNA. That definition directly matches the term named in the stem. By contrast,
transcription refers to a different idea: Transcription copies information from a DNA
template into RNA. Keeping these definitions separate helps prevent errors when the same
concepts appear in biochemical structures or pathways.
Question 2.
A student encounters this situation: Adenosine formed from adenine plus ribose. Which
term should the student select?
A. nucleic-acid denaturation
B. Chargaff rule
C. phosphodiester bond
D. nucleoside
Correct Answer: D. nucleoside
Explanation: The key point is that the clue points to nucleoside. A nucleoside contains a
nitrogenous base linked to a pentose sugar but no phosphate group. The example given -
Adenosine formed from adenine plus ribose. - is a direct application of that definition. The
alternative terms describe different structures, processes, or roles and therefore do not fit
the clue as closely.
,Question 3.
Which choice gives the clearest biochemical description of RNA structural and catalytic
roles?
A. Adenine is a purine base found in both DNA and RNA and normally pairs with thymine in
DNA or uracil in RNA.
B. A nucleic acid is a polymer of nucleotide residues that stores, transmits, or helps
express biological information.
C. RNA can fold into complex structures and some RNAs participate directly in catalysis as
ribozymes.
D. In ordinary double-stranded DNA, the amount of adenine equals thymine and the
amount of guanine equals cytosine.
Correct Answer: C. RNA can fold into complex structures and some RNAs
participate directly in catalysis as ribozymes.
Explanation: The defining feature is that RNA can fold into complex structures and some
RNAs participate directly in catalysis as ribozymes. That definition directly matches the
term named in the stem. By contrast, adenine refers to a different idea: Adenine is a
purine base found in both DNA and RNA and normally pairs with thymine in DNA or uracil
in RNA. Keeping these definitions separate helps prevent errors when the same concepts
appear in biochemical structures or pathways.
Question 4.
A student is distinguishing transcription from DNA. Which statement correctly describes
transcription?
A. Adenine and thymine form a standard DNA base pair stabilized by two hydrogen bonds.
B. Transcription copies information from a DNA template into RNA.
C. RNA is usually a single-stranded ribonucleotide polymer involved in information
transfer, structure, regulation, and catalysis.
D. DNA is usually a double-stranded polymer of deoxyribonucleotides that serves as
long-term genetic information storage.
Correct Answer: B. Transcription copies information from a DNA template into
RNA.
Explanation: The underlying principle is that transcription should be defined as follows:
Transcription copies information from a DNA template into RNA. This differs from DNA,
which is described by a separate set of properties. The distinction matters because
substituting one term for the other can change the predicted structure, location, or
biochemical outcome. The correct option therefore preserves the specific meaning of
transcription.
,Question 5.
A learner wants an example of cytosine. Which choice is best?
A. The C in a G-C base pair.
B. The T base paired with adenine in double-stranded DNA.
C. The G in a G-C base pair.
D. Comparing T and U structures and identifying the methyl group on thymine.
Correct Answer: A. The C in a G-C base pair.
Explanation: The correct interpretation is that The C in a G-C base pair. is a
representative example of cytosine. Cytosine is a pyrimidine base found in both DNA and
RNA and normally pairs with guanine. The other options were drawn from related module
concepts, but each illustrates a different biochemical feature. Matching the defining
feature to the example is the most reliable way to solve this type of problem.
Question 6.
A student encounters this situation: RNA polymerase producing an RNA transcript from a
gene. Which term should the student select?
A. phosphate group in nucleotides
B. pentose sugar
C. transcription
D. DNA
Correct Answer: C. transcription
Explanation: The most important distinction is that the clue points to transcription.
Transcription copies information from a DNA template into RNA. The example given - RNA
polymerase producing an RNA transcript from a gene. - is a direct application of that
definition. The alternative terms describe different structures, processes, or roles and
therefore do not fit the clue as closely.
Question 7.
Which option most accurately defines nucleotide?
A. Messenger RNA carries coding information that ribosomes read to direct protein
synthesis.
B. A nucleotide contains a nitrogenous base, a pentose sugar, and one or more phosphate
groups.
C. The 3-prime end of a nucleic-acid strand commonly has a free 3-prime hydroxyl group
available for extension.
D. The phosphate portion of a nucleotide contributes negative charge and participates in
phosphodiester bond formation.
Correct Answer: B. A nucleotide contains a nitrogenous base, a pentose sugar,
and one or more phosphate groups.
Explanation: The defining feature is that A nucleotide contains a nitrogenous base, a
pentose sugar, and one or more phosphate groups. That definition directly matches the
, term named in the stem. By contrast, messenger RNA refers to a different idea: Messenger
RNA carries coding information that ribosomes read to direct protein synthesis. Keeping
these definitions separate helps prevent errors when the same concepts appear in
biochemical structures or pathways.
Question 8.
A student encounters this situation: An A on one DNA strand aligned with T on the opposite
strand. Which term should the student select?
A. uracil
B. deoxyribonucleoside triphosphates
C. RNA structural and catalytic roles
D. A-T base pair
Correct Answer: D. A-T base pair
Explanation: The key point is that the clue points to A-T base pair. Adenine and thymine
form a standard DNA base pair stabilized by two hydrogen bonds. The example given - An
A on one DNA strand aligned with T on the opposite strand. - is a direct application of that
definition. The alternative terms describe different structures, processes, or roles and
therefore do not fit the clue as closely.
Question 9.
Which option provides the strongest example of A-T base pair?
A. An A on one DNA strand aligned with T on the opposite strand.
B. An RNA molecule forming an active three-dimensional catalytic structure.
C. A DNA polymerase selecting dGTP opposite a template cytosine.
D. DNA or RNA built from a repeating sugar-phosphate backbone with attached bases.
Correct Answer: A. An A on one DNA strand aligned with T on the opposite
strand.
Explanation: This choice is correct because An A on one DNA strand aligned with T on the
opposite strand. is a representative example of A-T base pair. Adenine and thymine form a
standard DNA base pair stabilized by two hydrogen bonds. The other options were drawn
from related module concepts, but each illustrates a different biochemical feature.
Matching the defining feature to the example is the most reliable way to solve this type of
problem.
