Okay, briefly:
1: Corn is a major food product for cattle. Cattle produce milk. Cheese is a milk product.
2: Corn makes ethanol. Ethanol is an alternative to gasoline. An increase in the production and use of ethanol to power automobiles means that (a) more corn is being used for this and so there is less for the cattle (and so alternative, more expensive feeds are needed for cattle) and (b) corn to feed cattle is more expensive because farmers can get more for it for fuel.
3: Because it costs more to feed the cows that produce the milk from which the various dairy products are made, the wholesale and retail prices of those products have increased.
As an aside, I think a gallon of milk here is $4.39 now. Who'da ever thunk lactose intolerance would be a good thing?
That's it for today's economics class. See you next week!