Wellcome to the Ranch Nart. You are supposed to know wheter a type is an interface or a class. Also to know wich implementation is more suitable for a given scenario. However I would recommend you to work a little with API before taking the exam. This chapter will suffice by large.
Off the top of my head, you need to know: 1. The main interfaces: Collection, Map, List, Set. 2. Implementing subclasses: Vector, ArrayList, LinkedList, Hashmap, Treemap, TreeSet 3. The iterators: Iterator, ListIterator 4. the Collections class HTH