Biology

No, they don't offer that.

For Bachelors in physiotherapy the candidates should clear 12th with science with minimum 50%.

You can check the link for more information:
http://www.indiastudychannel.com/resources/171800-Career-in-Nutrition-and-Dietetics-after-class-12.aspx

There is no entrance exam for admission. The admission is on the basis of 12th percentage. Admission council prepares a merit list on the basis of 12 percentage. For more details you can see the official website:
www.maharajascollege.in

No, you don't need to study biology. Just focus on your PCM.

Yes, you are eligible for BCA course after completing 12th science stream. To apply for BCA course you should complete 12th standard or equivalent examination in any discipline from a recognised university. You should score minimum 55% percentage of marks in 12th board examination.

Bachelor's degree in plant biology offer candidates to work in the laboratories, farming industry, classrooms as well as medical facilities.Candidates seeking to work in plant biology can browse professions like a plant biochemist, food science technician or agricultural manager. Candidates can work in various fields including farming sector, or teaching positions.
Top job positions: plant taxonomist, plant ecologist, plant morphologist, plant cytologist, plant physiologist, plant geneticist, palynologist, plant pathologist, teacher and lecturer, etc.

Students from PCM group can apply for IISER (Indian Institute of Science Education and Research) aptitude test. Most of the students who appear for this test will have PCM or PCB in class 12th. If you can answer three subjects confidently, you would have a great chance of ending up in IISER.

For more details of B.Sc in biology you can see the below link:
https://www.shiksha.com/science/colleges/b-sc-biology-colleges-navi-Mumbai
https://www.shiksha.com/science/colleges/b-sc-biology-colleges-Mumbai-all

Eligibility for M.Sc in biology:
As minimum criterion of eligibility, aspiring candidates are needed to have attained a Bachelor's degree in any of physics, bio-informatics/ biology (10+2 with mathematics)/ chemistry/ biotechnology/ biochemistry/ B.Tech. So, you can do M.Sc in biology.