Not sure if this is the right place to post it but...
please feel free to shift this thread if its in the wrong place. sorry for the inconvenience!
With those results, business would be tough as you know yourself since business cources are 1 of the most fought for courses every year.
Social science i won't really say its a dumping ground but you need to have an interest in the field since most social science grads would work more on the community, social service sort of jobs. It would depends on your interest to really see which social science might be better for you. NTU open house this sat so you can come down and learn more about them.
Biological science without bio would be pretty tough for you and chemistry... Personally i am often asking myself why did i choose chemistry...
Cut-Off Point to NUS,NTU,SMU Admission for JC & Poly Grads
NUS: http://nus.edu/oam/IGP/igp.htm
NTU: http://www3.ntu.edu.sg/oad2/pdfs/COP.pdf
SMU: http://www.smu.edu.sg/admissions/downloads/pdf/Samp%20Notif%20(SMU)%20COP%20FINAL%20with%20FAQs.pdf
I think with your result you can get in Business. Well. No harming applying for it.
Business is too common , if I were you , I will try science , biology , journalism :)
anyway go with your heart !
:)
Buy some wax to polish your head. You will be brighter with your decision.