Physics

Yes
10+2 with Physics, Chemistry, Maths students can apply for B.Sc.

Most of the institutions have their own exams but some top take JEE scores and this one is no different.
You need to get a good rank to get a seat in counselling. Participate in its counselling which is not held along with CSAB.

It is like asking what shall I do with the Cheese I made, while being a chef. Your career is your own dish and your 12 results your ingredients. What you need to do is see where you are good at. You can go in either of subjects, provided you had PCM or PCMB or any other but PCM constant. Striking the bell but needs determination and dedication which is equally important now.

Hello,
Maths is not compulsory. You just need basic knowledge of 11th-12th mathematics and that is enough for what is required. Good luck.

Getting grace marks must never be your priority. If you tried best, no need to worry. If you fail, still no fear, you have compartment too as an option. Just don't stop to worry and pause working hard. My best wishes.

Yes, you are eligible for B.Sc in biotechnology.