Science

No, but you can join OUAT only through your ICAR exam mark.

If you scored more than 90 marks in board exam, then securing 100-110 in OUAT is enough.

Yes, you can get B.Sc in Microbiology. You can get admission in Oxford College, but for that you have to qualify their entrance exam. You can get admission there.

If you are SC/ST/NT/OBC, you are luckier, you can get admission with 52% marks.
The case for Bachelors in Arts is opposite. It never went down below 75%, at least not in 2012.
This maybe primarily because, prospective engineers apply for a B.Sc course, in case they don't get a good college.

Please be specific about the question. I hope I will be able to answer your question once I understand it better. So, please ask the question again.

It is good that you recognized your weakness, and now if you think about business, then it is a vast stream and you can find business everywhere. Now, the only task left for you is to find the most trending business and start with it. Good luck.

For seeking admission to the Bachelor of Science course in physics, candidates must have completed their higher secondary examination in science stream and they must have secured good percentage of marks in the physics examination at their 10+2 level.

https://www.shiksha.com/science/colleges/m-sc-food-nutrition-colleges-Gujarat
Kindly visit this link.

Hello Subhas,
It's very nice to see your dream of doing M.Sc. Many of us cannot pursue regular courses and then the only option is distance education. I feel IGNOU is the best open university offering hundreds of courses via distance education. Just download brochure cum application form from the NET and follow steps given there.
Best wishes.

I think BMS is a better option as BBA includes maths in it.
All the best