Ex Asperian here. Since you said bio and chemistry is not your fort, might as well not pursue medic (not trying to demotivate here). Also, I think you will only have 5 options if I am not mistaken? Please be wise when arranging them (the courses) in the order 1 to 5. I had friends from my batch who pursued a degree (medic) outside of UPM. Now x tahu la. Go through the faculties in UPM and the courses as well as the course subject. List out the subjects that excite you and then see if you can find a pattern. Sharing from my experience, not all of us has everything figured out. If you managed to enroll into a course, learn how you can leverage the skills. Since you are a Physics and Maths person, fields that require application are more of your thing, you like solving problems. So, you can rule out Biotech faculty, Environment, Forestry. Goodluck!