In order to persue your B.Tech in Biotech, you have to appear for a competitive test including Mathematics and your selection will depend upon the clearance of this test covering all the papers of the test.With respect to your query regarding the appearance in IIT and VIT entrance tests, Mathematics cannot be ignored.
B.Sc Biotechnology course is conducted in almost in all the universities in India.
We cannot make any comparasion which stream is better B.Sc ( Biotechnology) or B.Tech in Biotechnology however, by completing the later course, you can get a job in an IT firm but in the former case, you need to complete M.Sc in Biotechnology and further doctorate is required in order to persue Reasearch - work in a Pharmectual - company and similarly for securing a job in a constituent college, you have to procure a Ph.D degree for a stable career.
There is no age - limit in completion of Ph.D degree.
In Ph.D programme after M.Sc in Biotechnology, you are entitled to get fellowship to the extent of Re 25000/- for the first two years and upon your satisfactory performance in the Reasearch, the fellowship is raised to three thousand additionally and later after procuring Ph.D degree, you may join Alembic, Glaxo etc with an attractive emoluments.
For B.Tech in Biotechnology, you may choose IIT, NIT, VIT etc.
For B.Sc in Biotechnology you may persue from any constituents colleges and other colleges of Kolkata and Mumbai university.