Chromosomal Aberrations Practice Questions
20 free Chromosomal Aberrations practice questions for the Zoology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What type of chromosomal aberration is characterized by the loss of a chromosome segment?
- A Deletion
- B Duplication
- C Inversion
- D Translocation
Correct answer: Deletion
Deletion involves the loss of a portion of a chromosome, resulting in missing genetic material. This can lead to serious genetic disorders due to loss of essential genes.
Down syndrome is caused by which type of chromosomal abnormality?
- A Monosomy
- B Trisomy 21
- C Deletion of chromosome 5
- D Translocation of chromosome 18
Correct answer: Trisomy 21
Down syndrome occurs due to trisomy 21, where individuals have three copies of chromosome 21. This results from nondisjunction during meiosis.
Which condition is caused by monosomy X?
- A Klinefelter syndrome
- B Turner syndrome
- C Down syndrome
- D Patau syndrome
Correct answer: Turner syndrome
Turner syndrome occurs when one of the X chromosomes is missing in females. This leads to developmental abnormalities such as short stature and infertility.
Which chromosomal aberration involves a segment of a chromosome being reversed?
- A Deletion
- B Duplication
- C Inversion
- D Translocation
Correct answer: Inversion
Inversion occurs when a segment of a chromosome breaks off and reinserts in the reverse orientation. This can disrupt gene function if breakpoints occur within genes.
Klinefelter syndrome is characterized by which chromosomal pattern?
- A XO
- B XXY
- C XYY
- D XXX
Correct answer: XXY
Klinefelter syndrome occurs in males with an extra X chromosome, resulting in an XXY karyotype. It often leads to reduced fertility and secondary sexual characteristics.
Which disorder is associated with trisomy 18?
- A Down syndrome
- B Edwards syndrome
- C Patau syndrome
- D Klinefelter syndrome
Correct answer: Edwards syndrome
Edwards syndrome is caused by trisomy 18, where an extra copy of chromosome 18 is present. It leads to severe developmental abnormalities and high mortality.
What is nondisjunction?
- A Mutation in a DNA sequence
- B Failure of chromosomes to separate properly
- C Exchange of genetic material between chromosomes
- D Loss of genetic material from a chromosome
Correct answer: Failure of chromosomes to separate properly
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate during cell division. This results in abnormal chromosome numbers in gametes.
Which chromosomal abnormality results in cri-du-chat syndrome?
- A Trisomy of chromosome 21
- B Deletion of the short arm of chromosome 5
- C Trisomy of chromosome 13
- D Duplication of the long arm of chromosome 18
Correct answer: Deletion of the short arm of chromosome 5
Cri-du-chat syndrome is caused by a deletion on the short arm of chromosome 5. It leads to a characteristic cat-like cry in infants and developmental delays.
Which type of chromosomal aberration involves the exchange of segments between non-homologous chromosomes?
- A Chromosomal inversion
- B Duplication
- C Translocation
- D Segmental deletion
Correct answer: Translocation
Translocation involves the transfer of chromosomal segments between non-homologous chromosomes. It can disrupt gene function or create fusion genes.
Patau syndrome is caused by trisomy of which chromosome?
- A Chromosome 13
- B Chromosome 18
- C Chromosome 21
- D Chromosome X
Correct answer: Chromosome 13
Patau syndrome results from trisomy 13, where there is an extra copy of chromosome 13. It causes severe intellectual disability and physical abnormalities.
Which chromosomal aberration leads to an extra copy of a chromosome segment?
- A Deletion
- B Inversion
- C Translocation
- D Duplication
Correct answer: Duplication
Duplication involves the repetition of a chromosome segment, resulting in extra genetic material. This can disrupt gene dosage balance.
Which human disorder is associated with an XYY karyotype?
- A Turner syndrome
- B Klinefelter syndrome
- C Jacob's syndrome
- D Down syndrome
Correct answer: Jacob's syndrome
Jacob's syndrome occurs in males with an XYY karyotype. Individuals are often taller than average and may have mild learning difficulties.
What is aneuploidy?
- A A normal diploid chromosome number
- B Duplication of the entire chromosome set
- C A mutation within a single gene
- D Loss or gain of one or more chromosomes
Correct answer: Loss or gain of one or more chromosomes
Aneuploidy refers to an abnormal number of chromosomes due to gain or loss. It commonly results from nondisjunction during meiosis.
Which condition results from trisomy 21 with an extra chromosome attached to another chromosome?
- A Mosaic trisomy 21 Down syndrome
- B Turner syndrome
- C Patau syndrome
- D Translocation Down syndrome
Correct answer: Translocation Down syndrome
Translocation Down syndrome occurs when part or all of chromosome 21 attaches to another chromosome. This still results in extra genetic material from chromosome 21.
Which type of inversion includes the centromere?
- A Paracentric inversion
- B Terminal inversion
- C Segmental inversion
- D Pericentric inversion
Correct answer: Pericentric inversion
Pericentric inversion includes the centromere within the inverted segment. It can affect chromosome structure and segregation during meiosis.
Which chromosomal abnormality is lethal in most cases before birth?
- A Trisomy 21
- B Trisomy 13
- C Monosomy autosomes
- D Klinefelter syndrome
Correct answer: Monosomy autosomes
Monosomy of autosomes is usually lethal because essential genes are missing. Only monosomy X (Turner syndrome) is viable in humans.
What is mosaicism?
- A Two or more genetically different cell lines
- B Every cell in the body has an identical chromosome set
- C Loss of a single chromosome from a cell
- D Duplication of genes within a chromosome
Correct answer: Two or more genetically different cell lines
Mosaicism occurs when an individual has two or more populations of cells with different genotypes. This results from mitotic errors after fertilization.
Which chromosomal abnormality is associated with Philadelphia chromosome?
- A Chromosomal inversion
- B Segmental deletion
- C Translocation
- D Duplication
Correct answer: Translocation
The Philadelphia chromosome results from a translocation between chromosomes 9 and 22. It is associated with chronic myeloid leukemia.
Which term describes the gain of an entire extra set of chromosomes?
- A Polyploidy
- B Aneuploidy
- C Monosomy
- D Deletion
Correct answer: Polyploidy
Polyploidy refers to the presence of more than two complete sets of chromosomes. It is common in plants but rare and usually lethal in humans.
Which factor increases the risk of chromosomal nondisjunction in humans?
- A Advanced maternal age
- B Very young maternal age
- C High protein diet
- D Physical exercise
Correct answer: Advanced maternal age
Advanced maternal age is associated with a higher risk of nondisjunction during meiosis. This increases the likelihood of conditions like Down syndrome.