Science

Firstly you must have 10+2 or equivalent degree with minimum 50% marks in Physics Chemistry English and Biology or Mathematics but Biology is compulsory. Then admission is done on the basis of marks secured in entrance exam.

There are a lot of colleges in Mumbai for B.Sc. Some of them are St. Xavier's College, University of Mumbai, Bhavan's college, K J Somaiya college of arts and commerce. It is a three year long course.

Yes, need to quit from B.Sc. If you want to do B.Tech through JEE Main.

No, it is not available.
Jadavpur University B.Sc Course Details
It is a three-year full-time course divided into 6 semesters. The institute provides B.Sc degree across five specializations:
Physics
Chemistry
Mathematics
Geological Sciences
Geography
Jadavpur University B.Sc Admission Guidelines:
Applicants

Both are Good on their own merit & exposure. Agriculture field offers job opportunities in horticulture, poultry farming, plant Science, soil Science, food Science, animal Science, etc. Job Titles: Crop specialist. Fertilizer sales representative. Food microbiologist. Food researcher, Plant genetici

Maharashtra has a number of colleges offering a wide range of professional degrees, diplomas and special courses. To be precise, over 132 colleges in Maharashtra offering biotechnology professional course/degree. List of Top BE/B.Tech in Biotechnology Colleges In Maharashtra based on 2022 Ranking:
RT

About placement:
The highest salary offered at UEM Kolkata: Rs. 72 Lacs per annum. All eligible students of all pass out batches of UEM Kolkata got 1 to 2 job offers on average. Placement of UEM continues until the last student is offered a job. Number of job offers generated for 2021 pass out batch

B.Sc. nursing is a course of 4 year. In Rajeev College of nursing you have to pay around INR 70k per year and you need 10+2 or equivalent degree with minimum of 50% marks in Physics, Chemistry, Biology and English.