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5.7 Inversions, Translocations & Polyploidy — Test 3
Q1. A chromosomal aberration characterised by pseudodominance, suppressed crossing over and irreversibility is:✓ Deletion
Q2. A structural change that causes crossover suppression and a position effect is a(n):✓ Inversion
Q3. Inversions are called crossover suppressors because:✓ Pairing and crossing over occur, but gametes carrying crossover products are inviable
Q4. A single crossover within the loop of a pericentric inversion heterozygote produces gametes with:✓ Duplications and deletions
Q5. A single crossover within a paracentric inversion loop produces:✓ A dicentric and an acentric chromosome
Q6. A mechanism that can move a gene from one linkage group to another is:✓ Translocation
Q7. An aberration that changes the order of genes but keeps them in the same linkage group is a(n):✓ Inversion
Q8. A cross-shaped (cruciform) pairing configuration of four chromosomes at meiosis is characteristic of a:✓ Translocation heterozygote
Q9. In a reciprocal translocation heterozygote, the segregation pattern that yields balanced, viable gametes is:✓ Alternate segregation
Q10. Rare XX males and XY females in humans most often arise from:✓ An X-Y translocation involving the SRY region
Q11. A phenotypically normal man is found to have 45 chromosomes (44 + XY equivalent). The most likely cause is a:✓ Robertsonian translocation
Q12. A Robertsonian translocation involving chromosome 21 is clinically important because it can cause:✓ Translocation Down syndrome
Q13. A chromosome in which both arms are genetically identical mirror images, formed by transverse centromere division, is called a(n):✓ Isochromosome
Q14. Triticum aestivum (bread wheat) is an example of a(n):✓ Allopolyploid
Q15. Autopolyploidy is best defined as having:✓ More than two chromosome sets, all from the same species
Q16. A woman is heterozygous for a pericentric inversion; crossing over occurs within the inversion in 26% of meioses. The chance her child has duplication/deletion-related disabilities is about:✓ 13%
Q17. The key difference between a pericentric and a paracentric inversion is that a pericentric inversion:✓ Includes the centromere within the inverted segment
Q18. During meiosis, a chromosome that lacks a homologous partner while all others are paired indicates:✓ Monosomy
Q19. Among the products of a translocation heterozygote, the gametes from adjacent-1 segregation are:✓ Unbalanced (duplication/deletion) and usually inviable
Q20. Match each aberration with its consequence and select the correct option.✓ A-ii, B-i, C-iv, D-iii