ASCP (CG) Verified Multiple Choice and Conceptual
Actual Emended Exam Questions With Reviewed
100% Correct Detailed Answers
Guaranteed Pass!!Current Update
1. What is the purpose of pepsin treatment in FISH protocol?
A. Denature chromosomal DNA
B. Digest cytoplasmic proteins and improve probe accessibility
C. Counterstain chromosomes
D. Hybridize the probe
Answer: B — Pepsin digests cytoplasmic proteins, improving probe access to
target DNA.
2. What is the primary role of 2x SSC during FISH procedures?
A. Fix chromosomes
B. Denature DNA
C. Wash unbound probe and improve signal intensity
D. Counterstain nuclei
Answer: C — 2x SSC is a standard saline citrate buffer used in washing steps to
remove non-specific binding and enhance signal clarity.
3. Which of the following helps reduce background fluorescence in FISH?
A. Overexposing the slide to UV
B. Extended probe incubation
C. Stringent post-hybridization washes
D. Decreasing hybridization time
Answer: C — Stringent washes (e.g., with high-temperature or high-stringency
buffers) remove non-specific hybridization, reducing background noise.
,4. Why is denaturation important during FISH probe preparation?
A. To stain the chromosomes
B. To separate the probe strands
C. To make the target DNA single-stranded for hybridization
D. To enhance metaphase spreads
Answer: C — Denaturation of both the probe and target DNA is essential to
allow hybridization.
5. What effect does inadequate pepsin digestion have on FISH signal?
A. Chromosomes will overstain
B. Probe will bind non-specifically
C. Hybridization will fail due to insufficient probe penetration
D. Signal will become fluorescent green
Answer: C — Without proper digestion, the probe cannot access the target
DNA efficiently.
6. What is DAPI used for in the FISH process?
A. A buffer to prepare 2x SSC
B. A counterstain that binds to DNA
C. A mitotic arresting agent
D. A fixative for slides
Answer: B — DAPI is a fluorescent dye that stains A-T rich regions of DNA and
is used to visualize chromosomes or nuclei.
7. Which temperature range is typically used for probe denaturation in FISH?
A. 25–30°C
B. 55–60°C
C. 70–75°C
, D. 95–100°C
Answer: C — Denaturation typically occurs at 72–75°C for several minutes
depending on the protocol.
8. What is the function of formamide in the hybridization buffer?
A. Prevents nonspecific binding by crosslinking DNA
B. Lowers the melting temperature of DNA to enable hybridization at lower
temperatures
C. Inhibits fluorescence
D. Stains the chromosomes
Answer: B — Formamide helps lower the melting temperature of DNA,
allowing hybridization at a lower and more controlled temperature.
9. A method used to improve the intensity of FISH probe signals. - ANSWER
Pepsin pretreatment
10. A solution that reduces temperature and improves the intensity of FISH probe
signals. - ANSWER 2x SSC
11. A type of tumor associated with chromosome 11. - ANSWER Wilm's
tumor
12. A type of sarcoma associated with the translocation t(11;22). - ANSWER
Ewing sarcoma
13. A type of eye cancer associated with chromosome 13 deletion. - ANSWER
Retinoblastoma
Actual Emended Exam Questions With Reviewed
100% Correct Detailed Answers
Guaranteed Pass!!Current Update
1. What is the purpose of pepsin treatment in FISH protocol?
A. Denature chromosomal DNA
B. Digest cytoplasmic proteins and improve probe accessibility
C. Counterstain chromosomes
D. Hybridize the probe
Answer: B — Pepsin digests cytoplasmic proteins, improving probe access to
target DNA.
2. What is the primary role of 2x SSC during FISH procedures?
A. Fix chromosomes
B. Denature DNA
C. Wash unbound probe and improve signal intensity
D. Counterstain nuclei
Answer: C — 2x SSC is a standard saline citrate buffer used in washing steps to
remove non-specific binding and enhance signal clarity.
3. Which of the following helps reduce background fluorescence in FISH?
A. Overexposing the slide to UV
B. Extended probe incubation
C. Stringent post-hybridization washes
D. Decreasing hybridization time
Answer: C — Stringent washes (e.g., with high-temperature or high-stringency
buffers) remove non-specific hybridization, reducing background noise.
,4. Why is denaturation important during FISH probe preparation?
A. To stain the chromosomes
B. To separate the probe strands
C. To make the target DNA single-stranded for hybridization
D. To enhance metaphase spreads
Answer: C — Denaturation of both the probe and target DNA is essential to
allow hybridization.
5. What effect does inadequate pepsin digestion have on FISH signal?
A. Chromosomes will overstain
B. Probe will bind non-specifically
C. Hybridization will fail due to insufficient probe penetration
D. Signal will become fluorescent green
Answer: C — Without proper digestion, the probe cannot access the target
DNA efficiently.
6. What is DAPI used for in the FISH process?
A. A buffer to prepare 2x SSC
B. A counterstain that binds to DNA
C. A mitotic arresting agent
D. A fixative for slides
Answer: B — DAPI is a fluorescent dye that stains A-T rich regions of DNA and
is used to visualize chromosomes or nuclei.
7. Which temperature range is typically used for probe denaturation in FISH?
A. 25–30°C
B. 55–60°C
C. 70–75°C
, D. 95–100°C
Answer: C — Denaturation typically occurs at 72–75°C for several minutes
depending on the protocol.
8. What is the function of formamide in the hybridization buffer?
A. Prevents nonspecific binding by crosslinking DNA
B. Lowers the melting temperature of DNA to enable hybridization at lower
temperatures
C. Inhibits fluorescence
D. Stains the chromosomes
Answer: B — Formamide helps lower the melting temperature of DNA,
allowing hybridization at a lower and more controlled temperature.
9. A method used to improve the intensity of FISH probe signals. - ANSWER
Pepsin pretreatment
10. A solution that reduces temperature and improves the intensity of FISH probe
signals. - ANSWER 2x SSC
11. A type of tumor associated with chromosome 11. - ANSWER Wilm's
tumor
12. A type of sarcoma associated with the translocation t(11;22). - ANSWER
Ewing sarcoma
13. A type of eye cancer associated with chromosome 13 deletion. - ANSWER
Retinoblastoma
