1. During which phase of meiosis do homologous chromosomes undergo crossing over?
A) Prophase I
B) Metaphase I
C) Anaphase I
D) Telophase I
Answer: A
Crossing over occurs during Prophase I, specifically in the pachytene stage.
2. The term aneuploidy refers to:
A) Complete set of chromosomes duplicated
B) Loss or gain of one or more chromosomes
C) Presence of extra sets of chromosomes
D) Chromosomal breakage and rearrangement
Answer: B
Aneuploidy is the presence of an abnormal number of chromosomes, such as trisomy or monosomy.
3. Which of the following is a common human autosomal trisomy compatible with life?
A) Trisomy 13
B) Trisomy 16
C) Trisomy 21
D) Trisomy 18
Answer: C
Trisomy 21 causes Down syndrome and is one of the few trisomies viable in humans.
4. The primary constriction of a chromosome is called the:
A) Telomere
B) Centromere
C) Kinetochore
D) Nucleolus
Answer: B
The centromere is the primary constriction where sister chromatids are joined.
5. Which staining technique is used to visualize G-bands on chromosomes?
A) C-banding
B) Q-banding
C) Giemsa staining
D) R-banding
Answer: C
Giemsa stain produces G-banding patterns on chromosomes.
6. The chromosomal abnormality characterized by the loss of the short arm of chromosome 5 is known as:
A) Cri-du-chat syndrome
B) Turner syndrome
C) Klinefelter syndrome
D) Patau syndrome
Answer: A
Cri-du-chat syndrome results from deletion of 5p (short arm of chromosome 5).
7. Which of the following terms describes the presence of three sets of chromosomes?
A) Aneuploidy
B) Polyploidy
C) Monosomy
D) Disomy
Answer: B
Polyploidy refers to having more than two complete sets of chromosomes.
8. In humans, sex determination is controlled by the presence or absence of which chromosome?
A) X chromosome
B) Y chromosome
C) Chromosome 21
D) Chromosome 13
Answer: B
The Y chromosome carries the SRY gene, which triggers male development.
9. The term satellite DNA refers to:
A) Highly repetitive, non-coding DNA found near centromeres and telomeres
B) Protein-coding DNA sequences
C) DNA sequences that code for ribosomal RNA
D) DNA sequences in mitochondria
Answer: A
Satellite DNA consists of tandemly repeated non-coding sequences mostly found in heterochromatic regions.
10. Robertsonian translocation occurs between which chromosomes?
A) Two acrocentric chromosomes
B) Two metacentric chromosomes
C) One submetacentric and one telocentric chromosome
D) Two telocentric chromosomes
Answer: A
Robertsonian translocations typically involve fusion of two acrocentric chromosomes at their centromeres.
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