distiguish between positive and negative gene control?

Answer 1

As one example, lactose leads to the expression of the genes of the lac operon. So, the presence of lactose brings about the expression of the genes. (You can find in your text the details of HOW that all happens.) Histidine is an example of negative gene control. The presence of histidine prevents the expression of the genes involved in synthesizing histidine.(Again, I'm sure you'll need the deatils which you can find in your text.)

Answer 2

a jerk gets rejected in the bar and does not breed, positive, a brilliant person dies by random act of terror ,negative, OK , I'll stick to automotive questions