hi,

see you can definitely take biology as an isolated subject from recognized education board like nios or other state board to become eligible for neet ug exam.

the basic eligibility criteria for neet ug is candidates need to study physics, chemistry biology and english as a subject in 12th standard and must score the qualifying exam.

marks criteria is as follows as per category wise,

general category-50% aggregate marks in pcb in 10+2 course

sc/st/obc category-40% aggregate marks in pcb in 10+2 course.