When gregg first started drinking alcohol, he needed only one or two beers to feel "buzzed"; now he needs at least four or five beers before he feels anything. what process describes gregg's need for more alcohol before feeling its effects?

The process that's behind gregg's need for more alcohol is called functional tolerance. Humans and animals develop tolerance when their brain functions adapt to compensate for the disruption caused by alcohol in both their behavior and their bodily functions. There are different, types of functional tolerance and the factors that influence their development are many, they start from the repetition at which someone is exposed to alcohol, to that person's environment.