Science

B.Sc nursing is good. If you have patience, then you can go for B.Sc nursing.

I am confident that you will find good colleges in your neighborhood. You will surely put up excellent performance, if you are determined from the beginning.

Since, you have done M.Sc in biotechnology, you can do MBA in biotechnology also. MBA in hospital administration is also good. But, as your background is M.Sc in biotechnology, I would suggest you to pursue MBA in biotechnology.
You can consider the below mentioned institutes:
1. Amity Institute of Biotechnology.
2. Bharati Vidyapeeth University, etc.
You can visit the below mentioned link:
https://www.way2college.com/

Yes, you can do. You can pursue MBA in biotechnology. There are many universities like:
1. Amity Institute of Biotechnology.
2. Bharathi Vidyapeeth University.
3. Global Business School and Research Centre, etc.

You need to study physics and mathematics and do sufficiently well to pursue a career in astronomy. The options are few, thus competition is fierce.
You can check the below mentioned link:
http://www.iiap.res.in/opportunities/career

B.Sc in agriculture has more scope.