If your subject requires an admissions test – be it the TSA, the Cambridge Law Test, the Cambridge Language Test or one of the individual college tests, you will need to sit this test when you go up for interview. Sometimes colleges request that you answer certain questions – for example the Problem question on the Cambridge Law Test – so make sure you do that research before you go up to sit the test. Some tests, such as the NSTP test for Physical Natural Sciences at certain colleges, is actually not really a test at all, but more like a set of unseen problems that you need to do before the interview, and which will be discussed in the interview, to see how you responded to the questions – and how you respond to new suggestions as to how you could answer them.
Other tests, such as the TSA and the Cambridge Law Test are marked separately and then used in conjunction with your interview score in order to decide whether to offer you a place. The most important thing – as at every stage of the admissions process – is to give yourself the time you need to think, answer using the text, or your own knowledge to back up your reasoning and make sure that you check your answer when you’re done to ensure you haven’t made any silly mistakes. Best of luck!!