<em>Yersinia pestis</em> is the bacterium responsible for the infamous Black Death, an epidemic that cause millions of deceases in Europe during the fourteenth-century. Black Death left a mark of people in Europe not only in their history, but also in their genome, since several studies have revealed that they immune system respond differently than people in other countries. People who survived Black Death had shown to be immune when reexposed to plague, since the bacterium responsible of plague is <em>Yersinia pestis</em> itself.
Semi permeable membrane will allow something to pass through them and something not and it will allow on the basis of size particles while differentialy permeable will include other factors also other than size and will depend on the need of the cell this is the main difference between them hope it helps<span />