Class 12 pcmb

Please forgive me for asking this doubt here, but because other subs r/jeeneetards and r/jee contain most jee aspirants, i couldn't get satisfactory answers. I am pcmb student forced to take biology but i want to go for jee only. My jee prep not doing good or i say i have to restart that from scratch (a lot of work need to be done for which time already less) + now have to prepare biology for class 12 boards. I don't have any basics covered in class 9/11/12, can u please guide me to how to score 90+ in biology in class 12 2026 board exams. Mods please please approve for once......