Greetings,

You are eligible to apply through the SCB channel by appearing for the IISER Aptitude Test (IAT)but not through the KVPY SB channel which is for students in the first year of their undergraduate science courses, however you can apply through the SX channel (for 12th students) for science courses like (B.Sc., B.Stat, etc.)

You will have to attain the minimum cut off marks to be called for further processing. I am attaching a few links for more information on this:

IISER ELIGIBILITY (official link)

http://www.iiseradmission.in/index.php/pages/eligibility

IISER aptitude test (exam details)

https://engineering.careers360.com/exams/iiser-aptitude-test

best of luck