Hello dear aspirant, hope you are doing well.

If you have studied biology for both the standards and have attended practicals and taken exams and have minimum of 50% of marks then irrespective of being an additional subject it will be counted valid. Had it been in 12th and not in 11th then it could've caused problem. Since you have taken in both standards it won't be a problem, just score above 50%.

Hope it helped.