Can a fistful of grain function for different parts of the requirements of the grain-offering? Look to the verses in Leviticus. And what happens when one part becomes impure? The Gemara pauses on a "teiku." Also, a question from Rava - delving further into the ritual impurity, with consideration to different levels of impurity, and how it is conveyed to the next item over that comes in contact with the object that is impure (or is not rendered impure as the case may be).