I've sent MOE an enquiry about this matter, the following is their reply:
We refer to your email that was sent to us on 28 February 2012.
We are sorry to inform you that for both Pure Biology and Combine Science (Biology/ Chemistry) cannot be used for the computation of aggregate point.
Should you have any further enquiries email us at [email protected].
Alternatively, you may speak with our Customer Service Executives at 6872 2220 (Mondays to Fridays: 8am to 6pm and Saturdays: 8am to 1pm) or call +65 6872 2220 via your local operator if you are calling from overseas.
Thank you.
Best Regards,
Ms Teo Yin Yin
Customer Services Branch, MOE
for PERMANENT SECRETARY (EDUCATION)
I'll do the escalation and verification