I love biology. So what should i do after class 12?
If you love to study biology then prepare yourself for NEET UG, AIIMS etc.
Try to take admission in medical college. For that you have to prepare for medical entrance exam.
Here the link in which all details about NEET UG exam like exam pattern, syllabus etc
https://medicine.careers360.com/exams/neet
Good luck.

