Undergraduate Level (B.S Program) :
1. KVPY exam (conducted by IISc)
2. IIT-JEE
3.Any National Olympiad (Not exactly sure)

Post-Graduate level :
Admissions only through GATE exam.
If you get a very good GATE rank, you can join in regular M.E. Program.
If your GATE rank is decent, then apply for a M . Sc program. Selection will be based on GATE score and a personal interview.

Doctorate Level :
If you get a good GATE rank, then there will be a personal interview. Selection will be easier. GATE qualification will be preferred. But even without GATE you can apply but your U.G. and P.G. scores should be good which might fetch you a call for a personal interview.

Project Assistant: For people who are unable to break through with the entrance exams, but want to pursue in their field of interest, this is a good option. Find a professor in IISc who works in your area of interest and mail them a good motivation letter. You may very well be called to work with the professor’s group. Would really be helpful to stay in touch with research as well during the personal interview later on.

Dear Zafir,

You can take admission in IISc Bangalore through KVPY, IIT JEE and NEET. 

Good Luck!!