Science

Dear aspirant, Glad to meet you. Eligibility criteria for pursuing B.Sc. Is 10 + to or equivalent passed from recognised board. Some universities consider Polytechnic Diploma after 10th as equivalent to 10 + 2 board while some universities do not consider is it as equivalent. So, it is not just about B.Sc. It is about the university. In some universities you can get admission in B.Sc. After Polytechnic Diploma while some universities may not Grant you admission until you have passed the 10 + 2 exams from a recognised board. IGNOU B.Sc. Eligibility :
Students must qualify 10+2 level with a Science stream or equivalent qualification from a recognised education board. IGNOU B.Sc. Admission Process:
Selection to the B.Sc. Course is based on merit secured in the last qualifying examination.

Dear aspirant, Glad to meet you. Yes you can do B.Sc. After Polytechnic as the eligibility says that you must be either a passed student of standard 12th or must be having a Diploma from an AICTE approved college
So first complete your Diploma successfully with good marks and then you can apply for the colleges of your choice. Your choice of doing an MBA after B.Sc. Is a good choice. So move on. One more thing that I want to tell you is that MBA is a very good course and if you want to do that then you are on a right track. But one advice that I want to tell you is that instead of going for B.Sc. If you somehow manage to get into some Engineering college then your can triple up the benefit.

Dear aspirant, Glad to meet you. You will be a regular candidate if you join school and start from class 11 after failing in class 12th. This is because, Private Candidate are those who give exam but are not enrolled in any school due to some reasons like have failed in 12th and again appearing in the exam to pass. So, if one fails in class 12th and then again appear for its examination on the basis of his or her previous registration in class 12 without joining any a school then he or she will be a private candidate
but as your going to take admission in school and starts from class11 then you don't need to worry you will be a regular candidate. In case you are asking about regular and private candidate in regarding with NEET then I would like to tell you that even if you pass your class 12th examination as a private candidate, you will be still eligible for NEET 2021 as private candidates are eligible for NEET examination until Supreme Court gives its judgement over the eligibility of private candidate and after that eligibility will depend upon the result of the judgement.