Learn English – made of vs made up of

The correct way to put this is "Where is it made?"

The rule about adding prepositions at the end of a sentence is: only do it if the sentence doesn't make any sense without it. "Where is it made?" makes sense without a preposition, so don't add one.

This resource cleared up this issue for me: http://grammar.quickanddirtytips.com/ending-prepositions.aspx

I've heard a radio program on this topic.

Made of is used when the material the subject consists of doesn't change during the process of making the subject. As in the example by Armen elsewhere on this page:

Chairs are made of wood.

Here, wood is still wood. It doesn't transform into something else.

On the other hand, made from is used when the material changed its nature. Again, another Armen example:

Paper is made from wood.

Now, wood disappeared — it was transformed into paper.

Some more examples:

• The house is made of bricks. [They are still bricks.]
• Wine is made from grapes. [Grapes turn into wine.]