CBSE Class 9 Answered

The exchange of genetic material between homologous chromosomes that occurs during meiosis is called crossing over. Since the chromosomes are homologous, breaks at corresponding points mean that the segments that are broken off contain corresponding genes , i.e., alleles. The broken sections are then exchanged between the chromosomes to form complete new units, and each new recombined chromosome of the pair can go to a different daughter sex cell. Crossing over results in recombination of genes found on the same chromosome, called linked genes.

Crossing over creates new combinations of genes in the gametes that are not found in either parent, contributing to genetic diversity. Crossing over helps to bring about genetic variability within a species by allowing for virtually limitless combinations of genes in the transmission from parent to off-spring.