They want to see your bank statements to gauge your conditions of living, and the likelihood that you will return home after the visit. Not having a bank account might appear to be unusual for people who want to visit the UK for a professional examination.
It is normal that younger people get money from older relatives. If so, the visa officials want to know if if the money comes from legal sources, if the amount is reasonable for your relative, and if it is truly a gift to you. So that part of your aunt's finances need to be explained.
So the best case is having had a bank account for some time prior to the appication. Deposits should exceed withdrawals and they need to come at a regular pattern. Creating an account now and depositing large amounts of money does not help.