Crossing over or genetic recombination is a stage in the late prophase of meiosis I where homologs lie close to each other in pairs to exchange chromosomal material creating new combination of genes as each homologs is derived from either the father or the mother.
This exchange determines the material to be inherited by the offspring producing genetic variation which males the offspring typically different from the parents (genetic variation).
The reticular formation can be said to be a network of nuclei in the brainstem that wakes or alert us to a sharp reaction or occurence at a particular time.
