Hello there,
For getting admission in any B.Tech course, you need to sit for entrance exams like JEE Main. Now, for JEE Main, you need Mathematics as your compulsory subject, else you are not eligible to sit for the examination.
For more information about JEE Main, check the link given below:
https://engineering.careers360.com/articles/jee-main-eligibility-criteria

Also, you need to have the basic concepts of Mathematics which are taught in 10+2 level since any engineering course, be it Biotechnology, requires mathematics. Without maths, you can go for BSc in Biotechnology. The scope for BSc in Biotechnology is good too.

You can check the colleges offering B.Tech in Biotechnology:
https://engineering.careers360.com/colleges/list-of-engineering-colleges-in-india?state=West%20Bengal&degree=B.E%20/B.Tech&branch=Biotechnology%20Engineering,Bio%20Engineering,Biomedical%20Engineering,Biochemical%20Engineering,Biotechnology

Hope this information helps you.
Good luck!!