Hey Supriya.

To score your desired marks in ICAR UG you must lay emphasis on each portion Physics, Chemistry, Biology equally as each of them have equal weightage in the exam.

You can refer to you 11th, 12th books for preparation. Make sure that you go through the NCERTs. Make notes for important topics, tricks, formulas so that you can revise them later. Manage your time well by making a schedule so that you also have ample time to revise.

Keep in mind the pattern and syllabus while studying. Make sure that you go through the previous year question papers and sample papers and practice well while keeping a check on the time.

Best of luck!