CG 2026 Study Guide Scientist Cytogenetics
Certification Practice Questions Answer Explanations
Chromosome Analysis Molecular Cytogenetics
Laboratory Methods Quality Control Exam
Preparation
SECTION 1: CYTOGENETICS FUNDAMENTALS (Questions 1–20)
Question 1. What is the primary purpose of cytogenetic analysis?
A. To measure protein expression
B. To detect chromosomal abnormalities
C. To sequence DNA
D. To culture microorganisms
Answer: B. To detect chromosomal abnormalities
Rationale: Cytogenetic analysis examines chromosome number, structure, and
organization to identify numerical and structural abnormalities associated with
genetic disorders, malignancies, and developmental abnormalities.
Question 2. How many chromosomes are present in a normal human somatic cell?
A. 23
B. 44
C. 46
D. 48
Answer: C. 46
Rationale: Normal human somatic cells contain 46 chromosomes (23 pairs),
including 22 pairs of autosomes and one pair of sex chromosomes (XX in females,
XY in males).
Question 3. What is a karyotype?
,A. The arrangement of chromosomes in a cell
B. The DNA sequence of a gene
C. The protein profile of a cell
D. The metabolic activity of a cell
Answer: A. The arrangement of chromosomes in a cell
Rationale: A karyotype is the systematic arrangement of chromosomes by size,
centromere position, and banding pattern. It is used to detect numerical and
structural abnormalities.
Question 4. Which type of chromosome has its centromere located in the middle?
A. Metacentric
B. Submetacentric
C. Acrocentric
D. Telocentric
Answer: A. Metacentric
Rationale: Metacentric chromosomes have the centromere located near the
middle, resulting in two arms of approximately equal length. Submetacentric
chromosomes have the centromere off-center.
Question 5. Which type of chromosome has its centromere located near one end?
A. Metacentric
B. Submetacentric
C. Acrocentric
D. Telocentric
Answer: C. Acrocentric
Rationale: Acrocentric chromosomes have the centromere located near one end,
resulting in a very short p arm and a long q arm. Human acrocentric chromosomes
include 13, 14, 15, 21, and 22.
Question 6. Which human chromosomes are acrocentric?
,A. 1, 2, 3
B. 13, 14, 15, 21, 22
C. 4, 5, 6
D. 7, 8, 9
Answer: B. 13, 14, 15, 21, 22
Rationale: Human acrocentric chromosomes are 13, 14, 15, 21, and 22. They have
short p arms that contain ribosomal RNA genes and satellite regions.
Question 7. What is the purpose of chromosome banding?
A. To identify individual chromosomes and structural abnormalities
B. To measure chromosome length
C. To count chromosome number
D. To extract DNA
Answer: A. To identify individual chromosomes and structural abnormalities
Rationale: Chromosome banding produces characteristic patterns of light and dark
bands along each chromosome. These patterns allow identification of individual
chromosomes and detection of structural abnormalities.
Question 8. Which banding technique is most commonly used in clinical
cytogenetics?
A. Q-banding
B. G-banding
C. R-banding
D. C-banding
Answer: B. G-banding
Rationale: G-banding (Giemsa banding) is the most commonly used banding
technique. It produces dark and light bands that allow identification of individual
chromosomes and structural abnormalities.
Question 9. What does the resolution of a karyotype refer to?
, A. The number of cells analyzed
B. The number of bands visible per haploid chromosome set
C. The chromosome count
D. The staining intensity
Answer: B. The number of bands visible per haploid chromosome set
Rationale: Resolution refers to the number of bands visible per haploid
chromosome set. Higher resolution (e.g., 550–850 bands) allows detection of
smaller structural abnormalities.
Question 10. What is the minimum resolution required for routine cytogenetic
analysis?
A. 200 bands
B. 400 bands
C. 550 bands
D. 850 bands
Answer: B. 400 bands
Rationale: A minimum resolution of 400 bands is required for routine cytogenetic
analysis. Higher resolutions (550–850 bands) are used for detecting subtle
abnormalities.
Question 11. What is a mosaicism in cytogenetics?
A. The presence of two or more cell lines with different chromosomal constitutions
B. The presence of a single cell line
C. The presence of extra chromosomes
D. The absence of chromosomes
Answer: A. The presence of two or more cell lines with different chromosomal
constitutions
Rationale: Mosaicism refers to the presence of two or more cell lines with
different chromosomal constitutions in the same individual. It results from
postzygotic mitotic errors.
Certification Practice Questions Answer Explanations
Chromosome Analysis Molecular Cytogenetics
Laboratory Methods Quality Control Exam
Preparation
SECTION 1: CYTOGENETICS FUNDAMENTALS (Questions 1–20)
Question 1. What is the primary purpose of cytogenetic analysis?
A. To measure protein expression
B. To detect chromosomal abnormalities
C. To sequence DNA
D. To culture microorganisms
Answer: B. To detect chromosomal abnormalities
Rationale: Cytogenetic analysis examines chromosome number, structure, and
organization to identify numerical and structural abnormalities associated with
genetic disorders, malignancies, and developmental abnormalities.
Question 2. How many chromosomes are present in a normal human somatic cell?
A. 23
B. 44
C. 46
D. 48
Answer: C. 46
Rationale: Normal human somatic cells contain 46 chromosomes (23 pairs),
including 22 pairs of autosomes and one pair of sex chromosomes (XX in females,
XY in males).
Question 3. What is a karyotype?
,A. The arrangement of chromosomes in a cell
B. The DNA sequence of a gene
C. The protein profile of a cell
D. The metabolic activity of a cell
Answer: A. The arrangement of chromosomes in a cell
Rationale: A karyotype is the systematic arrangement of chromosomes by size,
centromere position, and banding pattern. It is used to detect numerical and
structural abnormalities.
Question 4. Which type of chromosome has its centromere located in the middle?
A. Metacentric
B. Submetacentric
C. Acrocentric
D. Telocentric
Answer: A. Metacentric
Rationale: Metacentric chromosomes have the centromere located near the
middle, resulting in two arms of approximately equal length. Submetacentric
chromosomes have the centromere off-center.
Question 5. Which type of chromosome has its centromere located near one end?
A. Metacentric
B. Submetacentric
C. Acrocentric
D. Telocentric
Answer: C. Acrocentric
Rationale: Acrocentric chromosomes have the centromere located near one end,
resulting in a very short p arm and a long q arm. Human acrocentric chromosomes
include 13, 14, 15, 21, and 22.
Question 6. Which human chromosomes are acrocentric?
,A. 1, 2, 3
B. 13, 14, 15, 21, 22
C. 4, 5, 6
D. 7, 8, 9
Answer: B. 13, 14, 15, 21, 22
Rationale: Human acrocentric chromosomes are 13, 14, 15, 21, and 22. They have
short p arms that contain ribosomal RNA genes and satellite regions.
Question 7. What is the purpose of chromosome banding?
A. To identify individual chromosomes and structural abnormalities
B. To measure chromosome length
C. To count chromosome number
D. To extract DNA
Answer: A. To identify individual chromosomes and structural abnormalities
Rationale: Chromosome banding produces characteristic patterns of light and dark
bands along each chromosome. These patterns allow identification of individual
chromosomes and detection of structural abnormalities.
Question 8. Which banding technique is most commonly used in clinical
cytogenetics?
A. Q-banding
B. G-banding
C. R-banding
D. C-banding
Answer: B. G-banding
Rationale: G-banding (Giemsa banding) is the most commonly used banding
technique. It produces dark and light bands that allow identification of individual
chromosomes and structural abnormalities.
Question 9. What does the resolution of a karyotype refer to?
, A. The number of cells analyzed
B. The number of bands visible per haploid chromosome set
C. The chromosome count
D. The staining intensity
Answer: B. The number of bands visible per haploid chromosome set
Rationale: Resolution refers to the number of bands visible per haploid
chromosome set. Higher resolution (e.g., 550–850 bands) allows detection of
smaller structural abnormalities.
Question 10. What is the minimum resolution required for routine cytogenetic
analysis?
A. 200 bands
B. 400 bands
C. 550 bands
D. 850 bands
Answer: B. 400 bands
Rationale: A minimum resolution of 400 bands is required for routine cytogenetic
analysis. Higher resolutions (550–850 bands) are used for detecting subtle
abnormalities.
Question 11. What is a mosaicism in cytogenetics?
A. The presence of two or more cell lines with different chromosomal constitutions
B. The presence of a single cell line
C. The presence of extra chromosomes
D. The absence of chromosomes
Answer: A. The presence of two or more cell lines with different chromosomal
constitutions
Rationale: Mosaicism refers to the presence of two or more cell lines with
different chromosomal constitutions in the same individual. It results from
postzygotic mitotic errors.
