There are almost as many different types of four-wheel-drive systems as there are four-wheel-drive vehicles. It seems that every manufacturer has several different schemes for providing power to all of the wheels.
Human Male Chromosomes. In the normal karyotype of male chromosomes, 23 pairs of very long DNA molecules and their associated proteins carry the hereditary information of a man.
Sources: Biology Student. Depending on the type of karyotype, you can tell what type of organism it is, if it has 23 pairs then you would know it is a human because humans have 46 chromosomes, one half from your mom and one half from your dad, making 23 pairs.