Hello Manmeet

If you are seeking admission in MBBS course, admission is done on the basis of NEET UG exam. 
According to the eligibility criteria of NEET exam, candidates should have studied Physics, Chemistry, Biology/ Biotechnology subjects in the qualifying exam.

In your B.A course, you must have not studied these subjects, so, if you have completed your your 10+2 studies from science stream with Physics, Chemistry, Biology/Biotechnology and English as the core subjects in Class 11 and Class 12, then you can apply for the NEET exam on the basis of your Class 12th marks and you can submit the migration certificate issued by your school Board only.

Do let me know if you have any other query.

Good Luck!