Subject exam paper search

After the Pre-sessional English Course, I would like to take Polymer Science and Engineering MSc. There are on Metranet an ocean of already given exams: they could made and idea about how might be our nexts assessment works.
I'm trying to answer a question about Polymer Science.
1) Explain what is meant by the term 'isomer'.
Isomers are molecules which have the same atoms but different bonds among them.
2)Discuss three different types of isomeric structures found between repeat units in polymers. Use an appropriate structure as examples.
Polystyrene can have 3 isomeric structures: - atactic, in which the position of the phenyl is oriented randomly along the carbon atoms of the chain; - syndiodactic, where the phenyl groups are regularly alternating onto the carbon atom chain; - Isotactic, where the methyl groups are arranged on the same side.
It had better to have a graphic comparison.
3)Select one of the isomeric structures above and discuss the polymerisation process to ensure that the discussed structure is prepared.
Polymerisations which use Ziegler-Natta catalysts allow formation of the wanted isomer. Dependently by the chosen catalyst system, we could obtain only one isomer among the possible ones.

I chosen the simplest exercise, but there are some very difficult to solve! More or less, the difficulty of the italian exams is the same, perhaps in the italian ones there are much more calculate to do. In order to pass an exam, in Italy you have to cope firstly with the written task and then, if you have pass it, the oral examination.
Some exams are difficult to pass because of the professor: they reject students just for have said or done little mistakes. It happened to me as well.
I reckon I have to start to freshen up all my previous studies...