i think need to copy your way of studying -
do you have a tutor
did you study in the summer holidays
for bio, do you have a notes bible too?
do you suggest trying really really hard with bio next yr even if this does mean slacking off on my math subjects?

tutor - no (never), although considering one for english next year as my teacher failed badly with us this year
summer holidays - yes, but not too much, good to start the year fresh (to stop myself burning out before exams -like some of my unfortunate frineds)
bio notes - all hand written (without excessive highlighting) in a4 exercise books
slacking - personally I didn't put as much effort into bio (hence only aiming for a 40), because I felt that overdoing on one subject would jepordise my performances in 1+2s (which will all turn to 3+4s next year anyway). I put more effort into Unit 4 though as I fond there was far less things to wrote learn and more application (which I prefer). I never had Bio in my top 4 though - an early mindset.
What I also do is make sure I get at least 6 hours sleep a day, so that I feel fairly fresh for the morning periods of school. Also, I try to have as much fun in school as possible (minimal time in the library) by playing cricket or basketball, so that when I got home, I would feel less likely to get distracted.
+No facebook! (advice from a friends who got 99.95 last year -five raw 50s). This is also confirmed by this poll I created:
http://vcenotes.com/forum/index.php/topic,31960.0.html