Hi There,

You have lots of options open to you bing in the Science background.

In laymans term, other than engineering, you can opt for all fields
Few Options for you after 12th PCB includes:

• Medical Science: A 5 years MBBS degree course. Please note Rural Internship is a must here. You can also opt for Homeopathy, Allopathy, Ayurveda, Unani etc
• ParaMedical Sciences: Physiotheraphy, Speech therapy, Occupational therapy, Prosthetics and Orthotics, Medical lab Technology ,Optometry and Ophthalmic technology, Nutrition and Dietetics
• Veternary Sciences: It is a part of the Medical study, but considered a separate specialization, These are doctors who deals with Animals and their issues.
• Food Sciences and Nutrition: A 3 years course leading to you becoming a dietician or a nutritionists
• Pharmacy: Though here you would have to check the colleges. Since few Institutes mandatorily ask for a PCMB combination, where you would not be eligible.
• BioTechnology: It is a 3 years course, whereby Biology meets technology. The main work involves Research, whereby you would be involved in storing and maintaining Medical records for use later
• BioMedical Sciences: This is another field of Biology or Science, whereby inventions are made to make Medical equipments user friendly and small in size. eg. pacemaker
• ****Agriculture Science**:**As the name suggests, they re researchers who are into the process of bringing out new developments in the field of agriculture. eg. Hybrid quality seeds, soil etc
• Foresty and Wildlife Sciences: They are the ones who are responsible for maintaining the eco sysems, forests and wildlife conservationists.

Other than this you could also opt for Nonscience related fields like ARTS, Commerce, Designing, etc.

As far as the lists of Medical colleges in India are concerned, check:
http://www.medindia.net/education/medical_colleges.asp

Hope this helps.
Wish you good luck....