Answer:
I believe the experiment was too see if the flowers that would grow from the stem would turn out to be red in color. (Which is the reason they put red ink.)
(hope this helped :P)
Insulin is produced by beta cells of the pancreas for storing and disposing of the glucose in various parts of the body like liver. This activity is a differentiated function of the beta cells of pancreas only. Although gene for insulin production is present in all cells, it is expressed only in the beta cells. Hence, it is a differentiated function.