Hi

Irrespective of your marks obtained by you your additional subject will remain the same.

For example,

I know someone who had math as compulsory subject and Biology as an additional subject in class 12th , he got some 80 + marks in Biology but his marks in maths was some 60 + but additional subject still remained biology.

So,

Even if you have got more marks in your biology examination in comparison of your mark examination your biology will still remain as an additional subject.

Moreover,

You can refer to your Bihar board result i. e your marksheet the result clearly mentions the additional subject.

in case,

If you wanted to have Biology in the list of compulsory subjects and not as an additional subject to be eligible for Neet examination then I would like to tell you that even with Biology as an additional subject in your class 12th board examination you are eligible for Neet examination provided you fulfil rest of the criteria

Thankyou