i wanna give mpsc exams after 12th i hav science grup of physics chemistry & biology . what type of subject preparations i'll need to apear

i like biology and i want to get b.a.m.s degree but more of that i want to appear in competitive exams and move on high post ~ so please tell me what type of subject for mpsc exams can be convinent for me ! and what types of fileds and opportunities & services are there for students like me