Maths Spl

Yes, it is necessary to have knowledge of grad level mathematics if you're going to pursue a degree in biotech. If you're in 12th standard and if it's possible that you can still add a subject in your current curriculum then go for it.
Mathematics is compulsory for admission in government colleges, only private colleges don't have maths as a compulsory. Since you'll be opting for a biotech course (most probably a B.Tech in biotech) then you will require the knowledge of mathematics (grad level).
If you want to improve your maths grade/score then try consulting Math Online Tutor at: https://tutstu.com/tutors/Math/sub/18/COLLEGE
This way you'll be able to prepare for admission exams at your pace and at your own timings.

Hi Kratika,
Yale is an Ivy League university and hence you must have an excellent all-rounder profile. As part of the application process you must take the SAT and TOEFL. Apart from these tests you must not only have excellent academic grades but also have extracurricular activities, they want students who can contribute to the university and the society and not boring students or just bookworms. Full scholarships are difficult unless you have the profile. It is best you first check their website and build your profile. See these links:
https://admissions.yale.edu/freshman-application-process
https://admissions.yale.edu/what-yale-looks-for