Hii Anamika..

You just have to appear in class 12th board exams with CBSE board or NIOS with Biology as a repeating subject.

And then you can appear in Re - exam of Biology only. The thing you have to do is that you have to cover both 11th and class 12th part and syllabus for the examination.

This NIOS or repeating CBSE exam certificate is accepted throughout India for all the universities and it is totally valid.

Which is the best way through which you can give your senior secondary exams repeating with biology.

Hope it helps.

Best of luck for your future.