If you are a May 2010 candidate and you are taking higher economics you should be comfortable with the analysis of a tariff.
These are 2 past IB questions relating to tariff analysis:
* How do tariffs affect economic welfare? (Short trade 3)
* Using an appropriate diagram, explain who gains and who loses from the introduction of a tariff (Short trade 34)
An analysis that may be considered useful can be found in my wikispace here. The usual warning: make sure you listen to your own teacher before adopting what I say to my students....