MB ASCP Exam 1 – Molecular Biology | 2025/2026
Latest Edition | Actual Exam Questions with
Correct Answers | Graded A+
MB ASCP Exam 1 – Molecular Biology | Updated 2025/2026 edition featuring actual
exam-based questions with 100% correct answers. Content covers nucleic acid structure and
function, PCR and amplification methods, hybridization, sequencing technologies, molecular
oncology, inherited disorders, infectious disease testing, quality assurance, and laboratory safety
standards.
Overview
This exam prep resource delivers verified MB ASCP molecular biology exam-style questions with
fully correct answers. Designed to reinforce clinical laboratory skills, molecular diagnostic
applications, and critical thinking for certification success. Graded A+ for accuracy and
reliability. The MB ASCP exam typically includes 100 questions, testing knowledge in
molecular science, techniques, and clinical applications.
Answer Format
Correct answers are highlighted in bold green. Each response is explained with a rationale to
strengthen understanding of molecular biology principles, laboratory applications, and safe
diagnostic practices.
Exam Questions
1. What is the role of Taq polymerase in PCR?
A. Denature DNA
B. Synthesize new DNA strands
C. Anneal primers
D. Degrade RNA
Rationale: Taq polymerase, a thermostable enzyme, adds nucleotides to synthesize new
DNA strands during PCR extension.
2. Which nucleotide base pairs with guanine in DNA?
A. Adenine
B. Thymine
C. Cytosine
, D. Uracil
Rationale: Guanine pairs with cytosine via three hydrogen bonds in DNA’s double
helix.
3. What is the purpose of the extension step in PCR?
A. Separate DNA strands
B. Synthesize new DNA by polymerase
C. Bind primers
D. Purify DNA
Rationale: Extension (typically at 72°C) allows Taq polymerase to add nucleotides,
forming new DNA strands.
4. Which technique separates RNA molecules by size?
A. PCR
B. Agarose gel electrophoresis
C. Sequencing
D. Cloning
Rationale: Agarose gel electrophoresis separates RNA or DNA by size, visualized with
stains like SYBR Green.
5. What is the role of a forward primer in PCR?
A. Degrade DNA
B. Bind to the 5’ end of the target DNA
C. Denature DNA
D. Detect mutations
Rationale: Forward primers complement the 5’ end of the target sequence, initiating
DNA synthesis.
6. Which enzyme converts mRNA to cDNA in RT-PCR?
A. DNA polymerase
B. Reverse transcriptase
C. Taq polymerase
D. Ligase
Rationale: Reverse transcriptase synthesizes cDNA from mRNA for PCR amplification.
7. What is a common use of fluorescence in situ hybridization (FISH)?
A. Protein quantification
B. Detect chromosomal abnormalities
C. RNA amplification
D. Cell culture
Rationale: FISH uses fluorescent probes to identify chromosomal translocations or
deletions.
8. In Sanger sequencing, what causes chain termination?
A. Primers
, B. Dideoxynucleotides (ddNTPs)
C. Taq polymerase
D. Magnesium ions
Rationale: ddNTPs lack a 3’ hydroxyl group, stopping DNA synthesis in Sanger
sequencing.
9. What is a key ethical principle in molecular diagnostics?
A. Share patient data publicly
B. Ensure informed consent
C. Alter results for clarity
D. Ignore regulations
Rationale: Informed consent respects patient autonomy and complies with ethical
standards.
10.Which technique detects specific RNA sequences?
A. Southern blot
B. Northern blot
C. Western blot
D. ELISA
Rationale: Northern blot uses hybridization to detect specific RNA sequences.
11.What is the purpose of a PCR thermocycler?
A. Sequence DNA
B. Control temperature cycles for PCR
C. Purify RNA
D. Analyze proteins
Rationale: Thermocyclers automate denaturation, annealing, and extension steps in
PCR.
12.Which mutation is associated with chronic myelogenous leukemia (CML)?
A. BRCA1
B. BCR-ABL fusion
C. CFTR
D. TP53
Rationale: The BCR-ABL fusion gene, detected via PCR or FISH, is diagnostic for CML.
13.What is the purpose of a positive control in a PCR assay?
A. Inhibit amplification
B. Verify assay functionality
C. Denature DNA
D. Detect contamination
Rationale: Positive controls confirm that PCR reagents and conditions work correctly.
14.Which biosafety level is required for handling SARS-CoV-2 in a molecular
lab?
Latest Edition | Actual Exam Questions with
Correct Answers | Graded A+
MB ASCP Exam 1 – Molecular Biology | Updated 2025/2026 edition featuring actual
exam-based questions with 100% correct answers. Content covers nucleic acid structure and
function, PCR and amplification methods, hybridization, sequencing technologies, molecular
oncology, inherited disorders, infectious disease testing, quality assurance, and laboratory safety
standards.
Overview
This exam prep resource delivers verified MB ASCP molecular biology exam-style questions with
fully correct answers. Designed to reinforce clinical laboratory skills, molecular diagnostic
applications, and critical thinking for certification success. Graded A+ for accuracy and
reliability. The MB ASCP exam typically includes 100 questions, testing knowledge in
molecular science, techniques, and clinical applications.
Answer Format
Correct answers are highlighted in bold green. Each response is explained with a rationale to
strengthen understanding of molecular biology principles, laboratory applications, and safe
diagnostic practices.
Exam Questions
1. What is the role of Taq polymerase in PCR?
A. Denature DNA
B. Synthesize new DNA strands
C. Anneal primers
D. Degrade RNA
Rationale: Taq polymerase, a thermostable enzyme, adds nucleotides to synthesize new
DNA strands during PCR extension.
2. Which nucleotide base pairs with guanine in DNA?
A. Adenine
B. Thymine
C. Cytosine
, D. Uracil
Rationale: Guanine pairs with cytosine via three hydrogen bonds in DNA’s double
helix.
3. What is the purpose of the extension step in PCR?
A. Separate DNA strands
B. Synthesize new DNA by polymerase
C. Bind primers
D. Purify DNA
Rationale: Extension (typically at 72°C) allows Taq polymerase to add nucleotides,
forming new DNA strands.
4. Which technique separates RNA molecules by size?
A. PCR
B. Agarose gel electrophoresis
C. Sequencing
D. Cloning
Rationale: Agarose gel electrophoresis separates RNA or DNA by size, visualized with
stains like SYBR Green.
5. What is the role of a forward primer in PCR?
A. Degrade DNA
B. Bind to the 5’ end of the target DNA
C. Denature DNA
D. Detect mutations
Rationale: Forward primers complement the 5’ end of the target sequence, initiating
DNA synthesis.
6. Which enzyme converts mRNA to cDNA in RT-PCR?
A. DNA polymerase
B. Reverse transcriptase
C. Taq polymerase
D. Ligase
Rationale: Reverse transcriptase synthesizes cDNA from mRNA for PCR amplification.
7. What is a common use of fluorescence in situ hybridization (FISH)?
A. Protein quantification
B. Detect chromosomal abnormalities
C. RNA amplification
D. Cell culture
Rationale: FISH uses fluorescent probes to identify chromosomal translocations or
deletions.
8. In Sanger sequencing, what causes chain termination?
A. Primers
, B. Dideoxynucleotides (ddNTPs)
C. Taq polymerase
D. Magnesium ions
Rationale: ddNTPs lack a 3’ hydroxyl group, stopping DNA synthesis in Sanger
sequencing.
9. What is a key ethical principle in molecular diagnostics?
A. Share patient data publicly
B. Ensure informed consent
C. Alter results for clarity
D. Ignore regulations
Rationale: Informed consent respects patient autonomy and complies with ethical
standards.
10.Which technique detects specific RNA sequences?
A. Southern blot
B. Northern blot
C. Western blot
D. ELISA
Rationale: Northern blot uses hybridization to detect specific RNA sequences.
11.What is the purpose of a PCR thermocycler?
A. Sequence DNA
B. Control temperature cycles for PCR
C. Purify RNA
D. Analyze proteins
Rationale: Thermocyclers automate denaturation, annealing, and extension steps in
PCR.
12.Which mutation is associated with chronic myelogenous leukemia (CML)?
A. BRCA1
B. BCR-ABL fusion
C. CFTR
D. TP53
Rationale: The BCR-ABL fusion gene, detected via PCR or FISH, is diagnostic for CML.
13.What is the purpose of a positive control in a PCR assay?
A. Inhibit amplification
B. Verify assay functionality
C. Denature DNA
D. Detect contamination
Rationale: Positive controls confirm that PCR reagents and conditions work correctly.
14.Which biosafety level is required for handling SARS-CoV-2 in a molecular
lab?
