5.2 Structural Chromosomal Aberrations — Test 1

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Welcome! 5.2 Structural Chromosomal Aberrations — Test 1 — 20 questions, CSIR-NET style.

What this test covers

Inversions (paracentric vs pericentric)
Translocations & Robertsonian fusion
Philadelphia chromosome & cancer cytogenetics
Deletion syndromes & dicentric/ring chromosomes

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5.2 Structural Chromosomal Aberrations — Test 1

Q1. A broken chromosome segment that rotates 180° before rejoining produces the aberration called:✓ Inversion

Q2. An inversion in which the centromere lies OUTSIDE the inverted region is a:✓ Paracentric inversion

Q3. The fundamental difference between paracentric and pericentric inversions is:✓ The placement of the centromere relative to the inverted segment

Q4. Crossing over within the inversion loop of which heterozygote produces dicentric and acentric chromosomes?✓ Paracentric inversion

Q5. A dicentric chromosome is produced when crossing over occurs in an individual heterozygous for a:✓ Paracentric inversion

Q6. Inversions are considered crossover suppressors because:✓ Crossing over occurs but the crossover (recombinant) gametes are inviable

Q7. In an inversion heterozygote, if only that heterozygote arises de novo, the breakpoint most concerning for phenotype is one that disrupts:✓ A gene with an essential function

Q8. Exchange of chromosomal segments between non-homologous chromosomes is called:✓ Translocation

Q9. A reciprocal translocation is defined as the:✓ Exchange of segments between two non-homologous chromosomes

Q10. In a Robertsonian translocation, fusion occurs at the:✓ Centromeres (of two acrocentric chromosomes)

Q11. The outcome of a Robertsonian translocation between two acrocentric chromosomes is:✓ One metacentric chromosome plus a tiny fragment (short arms) usually lost

Q12. The Philadelphia chromosome results from a reciprocal translocation between chromosomes:✓ 9 and 22

Q13. The Philadelphia-chromosome translocation is clinically associated with:✓ Chronic myelogenous leukaemia

Q14. Which statement is NOT correct about the Philadelphia chromosome?✓ It causes mental retardation

Q15. Cri-du-chat syndrome is caused by:✓ Deletion of the short arm of chromosome 5

Q16. The chromosomal alteration underlying hereditary retinoblastoma is a:✓ Deletion on chromosome 13

Q17. Dicentric and ring chromosomes commonly appear after cells are exposed to:✓ Ionising (gamma/X) radiation

Q18. The term 'chromothripsis' refers to:✓ A single catastrophic shattering and reassembly of chromosomes seen in cancer

Q19. Acquired chromosomal translocations are especially common in:✓ Cancer

Q20. Match each aberration with its outcome and select the correct option.✓ A-ii, B-iv, C-i, D-iii