In the United States where does the warm air come from? Gulf of Mexico
Northwest United States
Canada
Northeast United States

Gulf of Mexico

Explanation:

In North America, for example, cold and dry air covering thousands of miles flows south from the Arctic, especially in winter, and warm moist air flows south from the Gulf of Mexico. These different types air are called air masses.

That would be the "active site".  There are three parts to the induced-fit model.  The substrate, the enzyme, and the active site.  The enzyme and the substrate form together like two puzzle pieces, and the active site is the space in between the two puzzle pieces.  It is still there when the enzyme and substrate have connected.  I hope I helped!  If I have wrong information, or you don't understand my analogy, please inform me so I can fix it.  :D  Thanks!