By the process of cellular differentiation which consists of physical and functional changes of the cell used by processes at the genetic level. The expression of these in each type of cell is different. That is to say that the type of cell follows at a time of development there is differential activation of some genes and repression of others
<h2>Answer:</h2><h3>1. Hepatitis B </h3><h3>2. Levels of circulating antibodies against a certain antigen.</h3><h2>Explanation:</h2><h3>Hope its help</h3>
