Final answer:
In humans, multisomies and monosomies of the X chromosome have less noticeable effects due to X inactivation, a process where one of the X chromosomes in each cell becomes inactive, resulting in the genes on that chromosome not being expressed. This mechanism allows females to compensate for their double genetic dose of X chromosome.
Step-by-step explanation:
In humans, the effects of multisomies and monosomies of the X chromosome are less noticeable compared to autosomal trisomies and monosomies. This is because of a process called X inactivation that occurs early in development. X inactivation involves one of the X chromosomes in each cell condensing into a dormant structure called a Barr body, resulting in the genes on that chromosome not being expressed. The particular X chromosome that is inactivated is random, but once it occurs, all cells descended from that cell will have the same inactive X chromosome. This mechanism allows females to compensate for their double genetic dose of X chromosome.