lol new to AN - bare with me
3rd!! How can you upset about that ranking?? However, if that's still not sufficient for your liking, why don't you see what the first ranked students are doing different to you? Also, if your score was bad, why don't you aid the entire class since your cohort will boost your marks up at the end of the year. Im sure being in the top three, there is some pressure from the teacher on you lot to help your fellow students.
But in regards to support, go back and ask your fellow students for help (no one looks bad asking for help) and ask them what you can do differently to help your own self out.
Also if you don't mind me asking, what did you receive for your first mark? You see, i'm doing biology too (a school in Pakenham) and for my first sac which was on osmosis in sultanas, i got first rank with 94%. Now I'm pretty happy with that mark (was unexpected) but I do think it was a fluke.