100+ Free SMB Practice Questions

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HLA-B*57:01 testing is indicated before prescribing which medication?

Codeine

Abacavir

Warfarin

Carbamazepine

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2026 Statistics

Key Facts: SMB Exam

100

Total Items

ASCP BOC

2h 30m

Exam Time

ASCP

$300

Exam Fee

ASCP

ACMG 2015

Variant Classification

5-tier framework

The ASCP SMB (Specialist in Molecular Biology) is a supervisory Specialist-level BOC credential. 100 MCQ items, 2h 30m, $300 fee. DISTINCT from the base MB Technologist credential. Master ACMG/AMP 2015 5-tier variant classification, PCR/NGS workflows, oncology molecular markers (BCR-ABL1 IS scale, EGFR T790M, BRAF V600E, MSI/MMR), and pharmacogenomics (CYP2D6, TPMT, HLA-B*57:01).

Sample SMB Practice Questions

Try these sample questions to test your SMB exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1During PCR, what occurs at the denaturation step (typically 94-98 degrees C)?

A.Double-stranded DNA separates into single strands by breaking hydrogen bonds

B.Primers anneal to complementary template sequences

C.Taq polymerase extends primers using dNTPs

D.Final products are stabilized by covalent bond formation

Explanation: Denaturation at 94-98 degrees C melts the hydrogen bonds between complementary bases, separating dsDNA into single-stranded templates that primers can subsequently bind. Without complete denaturation, amplification efficiency drops significantly.

2Using the Wallace rule, what is the approximate Tm of the primer 5'-ATGCCGTAAG-3'?

A.26 degrees C

B.30 degrees C

C.34 degrees C

D.40 degrees C

Explanation: Wallace rule: Tm = 2(A+T) + 4(G+C). For ATGCCGTAAG: A+T = 5, G+C = 5, so Tm = 2(5) + 4(5) = 10 + 20 = 30 degrees C. The Wallace rule is appropriate for short primers (<14 bp); longer primers require nearest-neighbor calculations.

3A qPCR run uses TaqMan chemistry. Which feature distinguishes TaqMan probes from SYBR Green detection?

A.TaqMan binds nonspecifically to all dsDNA, increasing background

B.TaqMan probes use sequence-specific fluorogenic hydrolysis with a reporter and quencher

C.TaqMan requires a melt curve for specificity confirmation

D.TaqMan cannot multiplex multiple targets

Explanation: TaqMan probes are sequence-specific oligonucleotides labeled with a 5' reporter dye and 3' quencher. During extension, Taq's 5'-3' exonuclease activity cleaves the probe, separating reporter from quencher and producing fluorescence proportional to amplicon. SYBR Green binds all dsDNA and lacks intrinsic specificity.

4In ddCt (delta delta Ct) relative quantification, what does the second delta represent?

A.Difference between target and reference gene Ct in each sample

B.Difference between sample dCt and calibrator (control) dCt

C.Difference between technical replicates

D.Difference between SYBR and TaqMan readings

Explanation: First dCt normalizes target to a reference gene within each sample. The second dCt compares the test sample's dCt to the calibrator sample's dCt. Fold change = 2^(-ddCt). This requires similar amplification efficiency between target and reference (~90-110%).

5Which technology provides absolute quantification without a standard curve and is ideal for low-allele-frequency variant detection and MRD monitoring?

A.SYBR Green qPCR

B.Sanger sequencing

C.Digital droplet PCR (ddPCR)

D.Microarray hybridization

Explanation: ddPCR partitions a sample into ~20,000 droplets, each undergoing individual PCR. Endpoint Poisson statistics yield absolute target concentration without a standard curve. ddPCR detects variant allele fractions as low as 0.01-0.1%, useful for BCR-ABL1 MRD and circulating tumor DNA (ctDNA).

6When designing PCR primers, which characteristic increases the risk of primer-dimer formation?

A.Tm difference between primer pairs of less than 5 degrees C

B.Complementary 3' ends between forward and reverse primers

C.GC content of 40-60%

D.Primer length of 18-25 nucleotides

Explanation: Primer-dimers form when primers self- or cross-anneal, especially via complementary 3' ends because the polymerase preferentially extends from a paired 3' OH. Avoid >3-bp 3' complementarity between forward and reverse primers. Tm matching, moderate GC content, and ~20 nt length are good design practices.

7Sanger sequencing relies on which key reagent to terminate chain extension at known nucleotides?

A.Dideoxynucleotides (ddNTPs) lacking a 3'-OH group

B.Phosphorothioate-modified dNTPs

C.Locked nucleic acids (LNAs)

D.Methylated cytosines

Explanation: Sanger uses fluorescently labeled ddNTPs that lack the 3'-OH required for phosphodiester bond formation. Random ddNTP incorporation terminates extension, generating fragments of all possible lengths that are resolved by capillary electrophoresis and read by laser detection of the fluorescent ddNTP at each position.

8On a Sanger electropherogram, a heterozygous SNV is most reliably called when:

A.A single peak with a small shoulder is observed

B.Two overlapping peaks of approximately equal height appear at the same position

C.Only the alternate allele peak is visible

D.The trace contains broad N-call bands

Explanation: A heterozygous SNV shows two superimposed peaks of roughly equal height (~50/50) at the same position because each allele contributes one base. Skewed ratios may indicate allele dropout, mosaicism, or contamination. Sanger's sensitivity floor is ~15-20% variant allele fraction.

9In an Illumina NGS library prep workflow, what is the purpose of indexing (barcoding)?

A.To prevent adapter dimer formation

B.To allow multiple patient samples to be pooled and sequenced together, then computationally separated

C.To improve fragment length uniformity

D.To repair single-strand nicks before ligation

Explanation: Index sequences (typically 8-10 nt barcodes) are added during adapter ligation. Multiplexed samples share a flow cell, and bioinformatics demultiplexing assigns reads to the correct sample by their index. Dual indexing further reduces index hopping and misassignment.

10Which NGS enrichment strategy is best suited for sequencing very large gene panels (>500 genes) or whole exomes from limited DNA input?

A.Amplicon-based PCR enrichment

B.Hybridization (capture-based) enrichment using biotinylated probes

C.Sanger tiling

D.Whole genome amplification only

Explanation: Hybrid capture uses biotinylated baits to pull down target regions via streptavidin beads. It scales efficiently to exomes and large panels with more uniform coverage and better detection of CNVs and structural variants than amplicon panels, which become impractical at very high target counts.

About the SMB Exam

ASCP BOC Specialist-level (supervisory) credential for senior molecular biology technologists. DISTINCT from the base MB Technologist credential. Validates expertise in molecular methods (PCR, qPCR, NGS, Sanger), oncology molecular diagnostics (BCR-ABL1, EGFR, BRAF, MSI/MMR), inherited disease and pharmacogenomics (CFTR, CYP2D6, TPMT, HLA-B*57:01), infectious disease molecular (HIV, HCV, MTB), bioinformatics + ACMG variant classification, and laboratory operations.

Questions

100 scored questions

Time Limit

2 hours 30 minutes

Passing Score

Scaled

Exam Fee

$300 (ASCP BOC)

SMB Exam Content Outline

25%

Molecular Methods

PCR, qPCR (TaqMan, SYBR), NGS (Illumina, Ion Torrent, Nanopore), Sanger, hybridization

20%

Oncology Molecular Diagnostics

BCR-ABL1 IS scale, JAK2, FLT3-ITD, EGFR T790M, BRAF V600E, KRAS, MSI/MMR, BRCA1/2

15%

Inherited Disease & Pharmacogenomics

CFTR, CYP2D6, CYP2C19, VKORC1, TPMT, HLA-B*57:01, DPYD

15%

Infectious Disease Molecular

HIV viral load, HCV genotype, MTB/RIF, HSV/CMV/BK, respiratory panels

10%

Bioinformatics, Variant Interpretation (ACMG)

ACMG/AMP 2015 5-tier classification, PVS1/PS/PM/PP and BA/BS/BP criteria

15%

Lab Operations, QC, Compliance, Specimen

CLIA high-complexity, CAP molecular checklist, FDA LDT 2024, contamination prevention

How to Pass the SMB Exam

What You Need to Know

Passing score: Scaled
Exam length: 100 questions
Time limit: 2 hours 30 minutes
Exam fee: $300

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

SMB Study Tips from Top Performers

1Master ACMG/AMP 2015 variant classification 5-tier system + 28 evidence criteria (PVS1, PS, PM, PP, BA, BS, BP)

2Know oncology actionable variants: BCR-ABL1 (CML, IS scale, MR4/MR4.5); EGFR L858R/exon 19 del + T790M resistance (lung); BRAF V600E (melanoma + CRC); KRAS G12C; MSI-H/dMMR (Lynch + ICI eligibility)

3Memorize critical pharmacogenomic alerts: TPMT for thiopurines (severe myelosuppression); DPYD for 5-FU (fatal toxicity); HLA-B*57:01 for abacavir (hypersensitivity)

4Understand NGS QC: depth of coverage, Q-scores, alignment, variant calling, orthogonal validation

5Know PCR contamination prevention: unidirectional workflow (pre-amp, post-amp), UV decontamination, dUTP/UNG, separate hoods, no-template controls

Frequently Asked Questions

What's the difference between MB and SMB?

MB(ASCP) is the entry-level Molecular Biology Technologist credential. SMB(ASCP) is the senior/supervisory Specialist credential — distinct exam, higher fee ($300), supervisory-level content (lab management, complex case interpretation, validation). Both are currently offered as separate credentials.

What is ACMG variant classification?

ACMG/AMP 2015 guidelines provide a 5-tier variant classification framework: Pathogenic / Likely Pathogenic / Variant of Uncertain Significance (VUS) / Likely Benign / Benign. 28 evidence criteria are weighted: PVS1 very strong pathogenic; PS1-4 strong pathogenic; PM1-6 moderate; PP1-5 supporting; BA1 stand-alone benign; BS1-4 strong benign; BP1-7 supporting benign. Variants are classified by combining the evidence criteria per scoring rules.

What pharmacogenomic targets should I know?

CYP2D6 (codeine activation, tamoxifen → endoxifen, SSRIs); CYP2C19 (clopidogrel, PPIs); CYP2C9 + VKORC1 (warfarin); TPMT/NUDT15 (thiopurines — azathioprine, mercaptopurine; severe myelosuppression); HLA-B*57:01 (abacavir hypersensitivity); HLA-B*15:02 (carbamazepine SJS in Asian); UGT1A1*28 (irinotecan, atazanavir); DPYD (5-FU/capecitabine — fatal toxicity).

How should I study for ASCP SMB?

Plan 80-120 hours over 12-16 weeks. Focus on Molecular Methods (25%) — master PCR/qPCR/NGS workflows; Oncology Molecular (20%) — drugs/targets/resistance mutations; ACMG variant classification; CYP/HLA pharmacogenomics. Use CLSI MM-series, ACMG/AMP 2015 guidelines, and CAP molecular pathology checklist.