Dear Ayush,

After completing your graduation in Biotechnology, you must go for post-graduation.
Go for IIT JAM Entrance Examination. IIT JAM is a national level examination which provides admission in IITs and IISc through Joint Admission Test.
JAM offers programmes like M.Sc, Joint M.Sc Ph.D, M.Sc Ph.d. Dual degree and for other programme.

Hope this helps!!