If you dont like to study Biology, you can pursue PCME (Electronics) or PCMCs (Computer Science) or PCMG (Geology).You are eligible for studying engineering..

If you dont like to study Mathematics, you can pursue PCBH ( Home science) or PCBS (Statistics). This is good for students focused on medicine and find it difficult to cope up with mathematics.

If you select science in PUC, you have an option to shift to commerce or arts stream in case you feel the need to do it in Graduation. LIke many science students who score less in PUC and also realized that they made a mistake by taking up science, they join B.Com, BA, BBM, BBA, etc.

But if you select Commerce or Arts, you cannot pursue Science Graduation programs. Some Paramedical Courses are now open even for commerce and arts students..