CG(ASCP) EXAM QUESTIONS AND ANSWERS
(VERIFIED AND WELL DETAILED ANSWERS)
LATEST 2025/2026
SECTION I: SPECIMEN PREPARATION, CULTURE, AND HARVEST
(20–25%)
Question 1
A bone marrow specimen is received for cytogenetic analysis. Which of the
following anticoagulants is LEAST likely to be toxic to cells in culture?
A. Sodium heparin
B. Lithium heparin
C. Sodium citrate
D. EDTA
Answer: B. Lithium heparin
Rationale: Lithium heparin is the preferred anticoagulant for cytogenetic
specimens because it is least toxic to cells in culture and does not interfere with
cell growth. Sodium heparin can be used but may affect cell viability, while EDTA
and sodium citrate are generally avoided due to their chelating effects .
Question 2
The optimal temperature for transport of amniotic fluid specimens for cytogenetic
analysis is:
A. 37°C
B. Room temperature (22–25°C)
,C. 4°C
D. 0°C
Answer: B. Room temperature (22–25°C)
Rationale: Amniotic fluid specimens should be transported at room temperature to
maintain cell viability. Extreme temperatures (37°C, 4°C, or freezing) can damage
the viable cells needed for culture establishment .
Question 3
Which of the following is the primary purpose of using a hypotonic solution during
the harvest procedure?
A. To swell cells and facilitate chromosome spreading
B. To arrest cells in metaphase
C. To preserve chromosome banding patterns
D. To fix the cells for slide preparation
Answer: A. To swell cells and facilitate chromosome spreading
Rationale: The hypotonic solution causes cells to swell by osmotic pressure, which
separates chromosomes and allows them to spread adequately on slides. Mitotic
inhibitors (e.g., colcemid) arrest cells in metaphase, and fixatives preserve
chromosome structure .
Question 4
A culture shows no visible cell growth after 7 days. Which of the following is the
MOST appropriate next step?
A. Discard the culture and report as culture failure
B. Re-feed the culture with fresh media and continue monitoring
C. Add more serum to the culture
D. Harvest the culture immediately
,Answer: B. Re-feed the culture with fresh media and continue monitoring
Rationale: Before declaring a culture failure, the technologist should attempt to
rescue the culture by providing fresh media and nutrients. Documentation of
culture failures is a quality indicator, but every effort should be made to establish
growth before discarding .
Question 5
Which banding technique is MOST commonly used for routine chromosome
analysis?
A. Q-banding
B. G-banding (GTG)
C. C-banding
D. NOR staining
Answer: B. G-banding (GTG)
Rationale: G-banding (Giemsa banding using trypsin) is the standard and most
widely used banding technique in clinical cytogenetics because it produces
consistent, high-resolution banding patterns that allow reliable chromosome
identification and detection of abnormalities .
Question 6
What is the purpose of colcemid (or colchicine) in cell culture?
A. To promote cell division
B. To swell the cells
C. To arrest cells in metaphase by disrupting spindle formation
D. To enhance chromosome banding
Answer: C. To arrest cells in metaphase by disrupting spindle formation
, Rationale: Colcemid is a spindle inhibitor that prevents the formation of the
mitotic spindle, arresting cells in metaphase when chromosomes are maximally
condensed and most visible for analysis. The optimal exposure time is critical—too
long leads to over-condensed chromosomes .
SECTION II: MOLECULAR CYTOGENETIC TESTING (15–20%)
Question 7
A FISH probe designed to detect a gene rearrangement where the probe spans the
breakpoint and signals split apart when a translocation occurs is called a:
A. Fusion probe
B. Break-apart probe
C. Enumeration (centromere) probe
D. Locus-specific probe
Answer: B. Break-apart probe
Rationale: A break-apart probe consists of two differently colored probes flanking
a gene of interest. When a translocation disrupts the gene, the signals split apart.
This strategy is used when multiple fusion partners are possible (e.g., MLL, ETV6) .
Question 8
Which of the following is the correct order of steps for FISH slide processing?
A. Denaturation → Hybridization → Post-wash → Counterstain
B. Hybridization → Denaturation → Post-wash → Counterstain
C. Post-wash → Denaturation → Hybridization → Counterstain
D. Denaturation → Post-wash → Hybridization → Counterstain
Answer: A. Denaturation → Hybridization → Post-wash → Counterstain
(VERIFIED AND WELL DETAILED ANSWERS)
LATEST 2025/2026
SECTION I: SPECIMEN PREPARATION, CULTURE, AND HARVEST
(20–25%)
Question 1
A bone marrow specimen is received for cytogenetic analysis. Which of the
following anticoagulants is LEAST likely to be toxic to cells in culture?
A. Sodium heparin
B. Lithium heparin
C. Sodium citrate
D. EDTA
Answer: B. Lithium heparin
Rationale: Lithium heparin is the preferred anticoagulant for cytogenetic
specimens because it is least toxic to cells in culture and does not interfere with
cell growth. Sodium heparin can be used but may affect cell viability, while EDTA
and sodium citrate are generally avoided due to their chelating effects .
Question 2
The optimal temperature for transport of amniotic fluid specimens for cytogenetic
analysis is:
A. 37°C
B. Room temperature (22–25°C)
,C. 4°C
D. 0°C
Answer: B. Room temperature (22–25°C)
Rationale: Amniotic fluid specimens should be transported at room temperature to
maintain cell viability. Extreme temperatures (37°C, 4°C, or freezing) can damage
the viable cells needed for culture establishment .
Question 3
Which of the following is the primary purpose of using a hypotonic solution during
the harvest procedure?
A. To swell cells and facilitate chromosome spreading
B. To arrest cells in metaphase
C. To preserve chromosome banding patterns
D. To fix the cells for slide preparation
Answer: A. To swell cells and facilitate chromosome spreading
Rationale: The hypotonic solution causes cells to swell by osmotic pressure, which
separates chromosomes and allows them to spread adequately on slides. Mitotic
inhibitors (e.g., colcemid) arrest cells in metaphase, and fixatives preserve
chromosome structure .
Question 4
A culture shows no visible cell growth after 7 days. Which of the following is the
MOST appropriate next step?
A. Discard the culture and report as culture failure
B. Re-feed the culture with fresh media and continue monitoring
C. Add more serum to the culture
D. Harvest the culture immediately
,Answer: B. Re-feed the culture with fresh media and continue monitoring
Rationale: Before declaring a culture failure, the technologist should attempt to
rescue the culture by providing fresh media and nutrients. Documentation of
culture failures is a quality indicator, but every effort should be made to establish
growth before discarding .
Question 5
Which banding technique is MOST commonly used for routine chromosome
analysis?
A. Q-banding
B. G-banding (GTG)
C. C-banding
D. NOR staining
Answer: B. G-banding (GTG)
Rationale: G-banding (Giemsa banding using trypsin) is the standard and most
widely used banding technique in clinical cytogenetics because it produces
consistent, high-resolution banding patterns that allow reliable chromosome
identification and detection of abnormalities .
Question 6
What is the purpose of colcemid (or colchicine) in cell culture?
A. To promote cell division
B. To swell the cells
C. To arrest cells in metaphase by disrupting spindle formation
D. To enhance chromosome banding
Answer: C. To arrest cells in metaphase by disrupting spindle formation
, Rationale: Colcemid is a spindle inhibitor that prevents the formation of the
mitotic spindle, arresting cells in metaphase when chromosomes are maximally
condensed and most visible for analysis. The optimal exposure time is critical—too
long leads to over-condensed chromosomes .
SECTION II: MOLECULAR CYTOGENETIC TESTING (15–20%)
Question 7
A FISH probe designed to detect a gene rearrangement where the probe spans the
breakpoint and signals split apart when a translocation occurs is called a:
A. Fusion probe
B. Break-apart probe
C. Enumeration (centromere) probe
D. Locus-specific probe
Answer: B. Break-apart probe
Rationale: A break-apart probe consists of two differently colored probes flanking
a gene of interest. When a translocation disrupts the gene, the signals split apart.
This strategy is used when multiple fusion partners are possible (e.g., MLL, ETV6) .
Question 8
Which of the following is the correct order of steps for FISH slide processing?
A. Denaturation → Hybridization → Post-wash → Counterstain
B. Hybridization → Denaturation → Post-wash → Counterstain
C. Post-wash → Denaturation → Hybridization → Counterstain
D. Denaturation → Post-wash → Hybridization → Counterstain
Answer: A. Denaturation → Hybridization → Post-wash → Counterstain
