No matter what, in order to go JC, you will need L1R5 and of course meet the COP of the JC you want to get into.
You should know what is L1R5, in case you don't know what it means:
You need English + 5 revelant subjects.
Btw, you need to pass your humanities to get into JC, though humanities is not necessary to be part of your 5 revelant subjects.
So lets say you have 8 subjects, good news is you can flunk 2 subjects at the most (humanities and english not included).

The best is don't fail any subjects.
Anyway, what I suggest is don't drop your bio, go for the exam if u think u can at least get a pass for it. There is no need for A1 or 2, just a simple pass will do. No need to die die must chiong for that subject. You will never know someday you might need that subject.