Question

If meiosistakes place before fusion of gametes then how is crossing over (recombination) possible since in crossing over homologous chromosomes from father and mother are involved.

Answer 1

Recombination occurs in gametes before fusion. Crossing over occurs between homologous chromosomes of father's maternal and paternal chromosomes (the chromosomes father received from his mother and father) and between homologous chromosomes of mother's maternal and paternal chromosomes. One of the father's homologous chromosome will be in the gamete. Similarly, for the mother's case. Now, these gametes will fuse.