Marcelo is right, part I won't ask you any UML-related questions. But I would not recommend you sitting for part I with any gaps in your UML skills. Part I has many questions (over 20%) about design patterns, which come very close with UML.
I second Yegor, even though part 1 doesn't have UML questions-one need to understand UML as all the design pattern books has UML notations. Not knowing UML will make it difficult to understand those patterns.