CAT

Call from IIM will depend on your score that has to be above 99% at least. Your class 10th and class 12th percentage are fine.

Yes, there are institutes which offer MBA admission without any entrance exam score. But it will be difficult to get into any top-100 Institute as they require exam score for admission. If you are going for direct admission than directly post your query to the respective college, instead of going to any agent or consultants.

Hi Mehnaz,
You should give REVA MAT in order to get admission into Reva university without giving any other entrance tests, and you may have to go for a personal interview if you are shortlisted for admission.

Know the exam pattern and syllabus in detail.
Get the right study material.
Take online mock tests.
Create Study Group
Utilise the Internet.
Be confident and stay motivated.

You need to have 99+ percentile to get into top IIM. To know more about the same visit: https://www.shiksha.com/mba/articles/cat-2016-how-much-percentile-is-enough-to-aim-for-top-iims-blogId-13048.

You can definitely apply for admission. Conversion depends on how you perform in the interview.

Keep your marks above 95, you will be eligible for any branch in the first round of counseling.

Yes, you can sit for CAT. Since you are an Arts Graduate, it would be better, if you join coaching classes for CAT preparation, and try and take a lot of mock tests to sharpen your skills in the various subjects on which questions are asked at CAT. CAT generally has three sections. Quantitative Aptitude, Verbal, Data Interpretation and logical Reasoning.

I believe, there is not much in scope in MBA biotechnology, there are not much placement opportunities here in India. But if you want to pursue your career outside India, then it MBA in biotech is good. You will get many opportunities there.