Science

No, it's not like that. All three streams are totally different, you can opt for what you want to learn more and explore.

No, maths is not compulsory to pursue biotechnology.

If you did not have computer applications then also you can apply for B.Sc (Hons) in CS because now everyone can do it, any candidate completed HSC with any stream.
All the best.

It depends on what kind of role you are expecting in the government 'Secret Agency'. The criteria is general and as per industrial standard for the post of analyst, inspector, operations, etc. However, for upper authority and (or) military intelligence in RAW, NSG, etc., they don't go for direct hir

Here is the list:
Acharya Narendra Dev Nagar Nigam Mahila Mahavidyalaya
Baba Baijnath Degree College
Brahmavart Post Graduate College
Captain Sukhwasi Singh Smarak Janta Mahavidyalaya
Chhatrapati Shahu Ji Maharaj University
Christ Church School

Dear Eqra,
Please see the below colleges in Kanpur for B.Sc. Physics (Hons):
Acharya Narendra Dev Nagar Nigam Mahila Mahavidyalaya
Baba Baijnath Degree College
Brahmanand College
Brahmavart Post Graduate College
Captain Sukhwasi Singh Smarak Janta Mahavidyalaya

Of course, you are eligible.

Dear Rimpa,
Below-mentioned link is for the colleges providing biotechnology in Kolkata. It could be based on ranking, fee structure and placements. You can compare between colleges and make the right choice of institute for you higher studies.
https://www.google.com/url?sa=t&source=web&rct=j&url=ht