A basic tenet of modern biology, first stated by Matthias Schleiden and Theodor Schwann in 1838–39, that cells<span> are the basic units of structure and function in living organisms. ... A </span>theory<span> of heredity must be reconciled with the </span>cell theory<span>.</span>
Traits that are passed down on an X or a Y chromosome are sex-linked traits. Most of the time males are affected by sex-linked traits because males only have one X and a Y. The Y is the chromosome that makes a man, a man.
I do believe that it is both naturally occurring and caused by human activity. Although science has proven that it is something that naturally progresses with time, humans have sped up the process. Hope this helps:)
The reason why stars does not die when it is there time is because they tend to fuse in different and more heavier elements. In that way, it prevents them from dying for they were able to have the components of different elements, extending their lives and prevent themselves from dying on the time that they were supposed to.
