MHT CET Medical202622 April 2026Evening ShiftBiologyPrinciples of Inheritance and VariationActual
In X and Y chromosomes, crossing over occurs only between ____.
Options
- Ahomologous regions of both X and Y
- Bnon-homologus regions of both X and Y
- Cnon-homologous region of X and homologous region of Y
- Dhomologous region of X and non-homologous region of Y
Correct answer
A. homologous regions of both X and Y
Step-by-step solution
The X and Y chromosomes are structurally different but share short regions of homology known as pseudoautosomal regions (PARs) at their tips. During meiosis in males, the X and Y chromosomes pair up and undergo crossing over (recombination) exclusively within these homologous regions. The non-homologous regions of the X and Y chromosomes do not undergo crossing over, which prevents the exchange of sex-determining genes (like the SRY gene on the Y chromosome). Therefore, crossing over occurs only between the homolog