hey i would recommend that you dont drop biology!i had exactly the same subjects as you and legal studies which means i had 14 units... and had more reasons to drop a subject and biology being one of the so called "lower scaled subject" was more likely to be dropped! however i ended up dropping physics even though i was coming 1st in it and felt really bad dropping it.. but in the end i think it was the best decision! i know biology has a lot of memorising to do but like someone mentioned earlier, the concepts are easier to grasp and i think its easier to get a higher mark in the hsc for biology (eg in the high 90's for bio compared to physics and chem) and the higher the hsc mark is, the more it contributes towards to your uai! anywaiz gudluck with ur decision!