Indian Institute of Science

You have to get rank under 100 or 200 hundred to get any IISC through GATE.

If you are asking for UG courses then the college does not provide any engineering courses in genetics. It has biology course in which one of the subjects is genetics. Check for a detailed list of courses at the link provided below:
https://www.shiksha.com/university/indian-institute-of-science-Bangalore-22350.

Yes, you need to. Check our JEE Mains college predictor:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor?utm_source=connect&utm_medium=CR_JEECP&utm_campaign=4067795

It depends on the results of JEE Advanced. In order to get admission in IISC, you must score AIR rank under 50 and in IITs. It must be under 5000.

Admission is based on the rank obtained in IIT-JEE/ National Eligibility-cum-Entrance Test (NEET). Minimum Eligibility to Apply is a pass mark of 60% in class 12 with Mandatory Subjects : Chemistry, Physics, Mathematics. Candidate must have studied Biology/ Statistics/ Electronics/ Computer Science as an optional subject. Interested candidates can apply online with required information.
There are over 157 B.Sc. in Biology colleges in India. Please refer to the link provided below for a detailed list of these colleges.
https://www.shiksha.com/science/colleges/b-sc-biology-colleges-india