I agree with the others that it's the amount of information you are required to remember that makes then troublesome.
For some subjects, you have to fill your head with information that you ae unlikely to have to use. My favourite example is the titles of the 18 annexes to the Chicago Convention. You can be asked what annexe X is in the exam. In real life, you would just look it up!
Also don't think they are easy because they are multi choice. Often it's a fine line between two possible answers and you will get no credit for picking the second best. There is often the issue of ambiguous questions to deal with.
Although a good memory helps a lot, I think it's best to make sure you understand the underlying principles so that if a weird question comes up, you can make a good stab at it.