Hello Dear Student,

Are you asking your query for NEET-UG entrance exam? If you have done B.Tech and Masters in other fileds then why are you going 6 years back to appear in a 12th level entrance examination for MBBS and BDS Courses? I think you should make your Career in your current relevant field.

Anyways, Coming on your Question, your Case is very complicated, I don't think you can appear in NEET-UG entrance examination by giving just the exam of Biology after 7 years through NIOS Board and are you appearing in other exams too Physics Chemistry of NIOS? Because Eligibility Criteria for NEET-UG is PCB, PCB is a mandatory stream Criteria for appearing in NEET-UG exam, If you have done 12th in 2013 and you are giving just exam of only Biology in 2021 and you are thinking about to Merge Subject of Biology with 2013 Result then in this Case I don't think they will accept your application, I hope you are doing Complete 12th with PCB from NIOS Board, If Yes then you can appear in the exam and If No then it's really difficult to answer your Query, I this Case I would advise you to Contact NTA NEET-UG Authorities via Call or email for Clarification, You can also contact to Dr Amit Gupta Sir (Senior Biology Faculty from Kota Rajasthan and NEET-UG activist) on Twitter and Unacademy, he have very Good legal knowledge about this exam.

All the Best