如题,实在不知道要研究什么

potassium fertilizer's effect on bean plants.
doesn't have to be complicated, but you have to be very detailed when you investigate

You know you are supposed to come up with your own thesis, right?
This may sound corny, but IB is a way of thinking. Please get the most out of it.
Of course, I guess one can't be original when it comes to Bio. Why not try English? Just a sidenote: it is proven that statistically, English EEs score much higher than Science EEs. Many of the apparatus/ research equipments are unavailable, hence hendering the depth of analysis one can have on any given topic. 

各种语法错误。。平常聊天写多了
my mom is a pharmacist

Well, best of luck. You might be able to pull off a decent mark!
Hot Pot is a neat concept...I miss it so much.