Traits that are sex-linked are carried on either the X or Y chromosome. If they are carried by a female, they are X-linked traits, and if they are carried by a male, they are Y-linked traits.
The endoplasmic reticulum serves many general functions, including the folding of protein molecules in sacs called cisternae and the transport of synthesized proteins in vesicles to the Golgi apparatus.
Homo sapiens means wise human being, it one of several species grouped into the genus Homo, but it is the only one that is not extinct. It is the specie where all human beings belong. They replaced Neanderthals during 30,000 BC. Scientists believe that Homo sapiens appeared in Africa between 150,000 and 200,000 years ago.
There are two sphincters in the human body
