TEST BANK
ASCP Molecular Biology (MB) Exam Prep Test Bank |
Latest Edition | Verified Questions & Correct Answers
with Detailed Rationales | A+ Rated Study Resource
2026/2027 Frequently Most Tested Questions and 100%
Accurate From Past papers | Graded A+ , Reviewed and
Updated | 100% Guarantee Pass | Latest Exam and Newest
Version!!!
Which bases are classified as pyrimidines?
a. Adenine and Guanine
b. Cytosine, Thymine, and Uracil
c. Adenine and Thymine
d. Guanine and Cytosine
,✔️ Correct Answer: B
Rationale: Pyrimidines are nitrogenous bases with a single-ring structure. Cytosine,
thymine, and uracil are the three pyrimidines found in nucleic acids. Adenine and
guanine (Options A and D) are purines, which have a double-ring structure. Option C
incorrectly pairs adenine (a purine) with thymine (a pyrimidine).
Which bases are classified as purines?
a. Cytosine and Uracil
b. Adenine and Guanine
c. Thymine and Guanine
d. Adenine and Cytosine
✔️ Correct Answer: B
Rationale: Purines are nitrogenous bases with a double-ring structure. Adenine and
guanine are the two purines found in nucleic acids. Cytosine and uracil (Option A) are
pyrimidines. Option C incorrectly pairs thymine (a pyrimidine) with guanine (a purine).
Option D incorrectly pairs adenine (a purine) with cytosine (a pyrimidine).
How are nucleotides joined together to form nucleic acids?
a. Hydrolysis
b. Condensation
c. Oxidation
d. Reduction
✔️ Correct Answer: B
Rationale: Nucleotides are joined by condensation reactions (also called dehydration
synthesis) that form phosphodiester bonds between the 5' phosphate of one nucleotide
and the 3' hydroxyl of another. Hydrolysis (Option A) breaks these bonds. Oxidation
(Option C) and reduction (Option D) are not the mechanisms for joining nucleotides.
What is the primary function of mRNA?
,a. Carries the genetic code from DNA to ribosomes for protein synthesis
b. Brings amino acids to ribosomes
c. Forms the ribosome structure
d. Acts as an enzyme for replication
✔️ Correct Answer: A
Rationale: Messenger RNA (mRNA) carries the genetic code transcribed from DNA to the
ribosome, where it is translated into protein. tRNA (Option B) brings amino acids to the
ribosome. rRNA (Option C) forms the ribosome structure. Option D describes the
function of enzymes like DNA polymerase, not mRNA.
What is the role of tRNA?
a. Decodes mRNA and matches amino acids to codons
b. Synthesizes DNA
c. Transports lipids
d. Forms ribosomal subunits
✔️ Correct Answer: A
Rationale: Transfer RNA (tRNA) decodes mRNA codons by carrying specific amino acids
to the ribosome during translation. Option B describes DNA polymerase. Option C
describes lipid transport proteins. Option D describes rRNA.
Which type of RNA forms part of the ribosome and coordinates tRNA-mRNA
interactions?
a. mRNA
b. tRNA
c. rRNA
d. snRNA
✔️ Correct Answer: C
Rationale: Ribosomal RNA (rRNA) forms the structural and catalytic core of ribosomes
and coordinates tRNA-mRNA interactions during translation. mRNA (Option A) carries
genetic information. tRNA (Option B) brings amino acids. snRNA (Option D) is involved in
splicing.
, In feedback inhibition, how does the end product regulate enzyme activity?
a. It binds to the active site to block the substrate
b. It acts as a noncompetitive inhibitor binding to the allosteric site
c. It denatures the enzyme
d. It increases enzyme synthesis
✔️ Correct Answer: B
Rationale: In feedback inhibition, the end product binds to the allosteric site of the
enzyme, causing a conformational change that reduces enzyme activity. This is a
noncompetitive inhibition mechanism. Option A describes competitive inhibition. Option
C describes denaturation. Option D is the opposite of feedback inhibition.
Which enzyme removes nucleotides one at a time from the end of a DNA or RNA chain?
a. Endonuclease
b. Exonuclease
c. Ligase
d. Primase
✔️ Correct Answer: B
Rationale: Exonucleases remove nucleotides one at a time from the ends of DNA or RNA
chains. Endonucleases (Option A) cut within the molecule. Ligase (Option C) joins DNA
fragments. Primase (Option D) synthesizes RNA primers.
Which enzyme cuts phosphodiester bonds within a DNA molecule at specific palindromic
sites?
a. Endonuclease
b. Ligase
c. DNA polymerase
d. Gyrase
ASCP Molecular Biology (MB) Exam Prep Test Bank |
Latest Edition | Verified Questions & Correct Answers
with Detailed Rationales | A+ Rated Study Resource
2026/2027 Frequently Most Tested Questions and 100%
Accurate From Past papers | Graded A+ , Reviewed and
Updated | 100% Guarantee Pass | Latest Exam and Newest
Version!!!
Which bases are classified as pyrimidines?
a. Adenine and Guanine
b. Cytosine, Thymine, and Uracil
c. Adenine and Thymine
d. Guanine and Cytosine
,✔️ Correct Answer: B
Rationale: Pyrimidines are nitrogenous bases with a single-ring structure. Cytosine,
thymine, and uracil are the three pyrimidines found in nucleic acids. Adenine and
guanine (Options A and D) are purines, which have a double-ring structure. Option C
incorrectly pairs adenine (a purine) with thymine (a pyrimidine).
Which bases are classified as purines?
a. Cytosine and Uracil
b. Adenine and Guanine
c. Thymine and Guanine
d. Adenine and Cytosine
✔️ Correct Answer: B
Rationale: Purines are nitrogenous bases with a double-ring structure. Adenine and
guanine are the two purines found in nucleic acids. Cytosine and uracil (Option A) are
pyrimidines. Option C incorrectly pairs thymine (a pyrimidine) with guanine (a purine).
Option D incorrectly pairs adenine (a purine) with cytosine (a pyrimidine).
How are nucleotides joined together to form nucleic acids?
a. Hydrolysis
b. Condensation
c. Oxidation
d. Reduction
✔️ Correct Answer: B
Rationale: Nucleotides are joined by condensation reactions (also called dehydration
synthesis) that form phosphodiester bonds between the 5' phosphate of one nucleotide
and the 3' hydroxyl of another. Hydrolysis (Option A) breaks these bonds. Oxidation
(Option C) and reduction (Option D) are not the mechanisms for joining nucleotides.
What is the primary function of mRNA?
,a. Carries the genetic code from DNA to ribosomes for protein synthesis
b. Brings amino acids to ribosomes
c. Forms the ribosome structure
d. Acts as an enzyme for replication
✔️ Correct Answer: A
Rationale: Messenger RNA (mRNA) carries the genetic code transcribed from DNA to the
ribosome, where it is translated into protein. tRNA (Option B) brings amino acids to the
ribosome. rRNA (Option C) forms the ribosome structure. Option D describes the
function of enzymes like DNA polymerase, not mRNA.
What is the role of tRNA?
a. Decodes mRNA and matches amino acids to codons
b. Synthesizes DNA
c. Transports lipids
d. Forms ribosomal subunits
✔️ Correct Answer: A
Rationale: Transfer RNA (tRNA) decodes mRNA codons by carrying specific amino acids
to the ribosome during translation. Option B describes DNA polymerase. Option C
describes lipid transport proteins. Option D describes rRNA.
Which type of RNA forms part of the ribosome and coordinates tRNA-mRNA
interactions?
a. mRNA
b. tRNA
c. rRNA
d. snRNA
✔️ Correct Answer: C
Rationale: Ribosomal RNA (rRNA) forms the structural and catalytic core of ribosomes
and coordinates tRNA-mRNA interactions during translation. mRNA (Option A) carries
genetic information. tRNA (Option B) brings amino acids. snRNA (Option D) is involved in
splicing.
, In feedback inhibition, how does the end product regulate enzyme activity?
a. It binds to the active site to block the substrate
b. It acts as a noncompetitive inhibitor binding to the allosteric site
c. It denatures the enzyme
d. It increases enzyme synthesis
✔️ Correct Answer: B
Rationale: In feedback inhibition, the end product binds to the allosteric site of the
enzyme, causing a conformational change that reduces enzyme activity. This is a
noncompetitive inhibition mechanism. Option A describes competitive inhibition. Option
C describes denaturation. Option D is the opposite of feedback inhibition.
Which enzyme removes nucleotides one at a time from the end of a DNA or RNA chain?
a. Endonuclease
b. Exonuclease
c. Ligase
d. Primase
✔️ Correct Answer: B
Rationale: Exonucleases remove nucleotides one at a time from the ends of DNA or RNA
chains. Endonucleases (Option A) cut within the molecule. Ligase (Option C) joins DNA
fragments. Primase (Option D) synthesizes RNA primers.
Which enzyme cuts phosphodiester bonds within a DNA molecule at specific palindromic
sites?
a. Endonuclease
b. Ligase
c. DNA polymerase
d. Gyrase
