Delhi University takes merit based admission for BSc(H) courses. Merit Based means the marks you scored in your class 12th examination is the basis.

Here is the eligibility criteria for BSc(H) Botany /zoology/ Microbiology

55% or more marks in aggregate of 3,subjects (Practical &Theory together) and passing in one compulsory language i.e. English with 50% marks.

MANDATORY SUBJECTS TO BE INCLUDED IN BEST 4 CALCULATION ARE

PHYSICS, CHEMESTRY, BIOLOGY/BIOTECHNOLOGY

Here I am providing you the detailed link which will help you in calculation of your best of 4 percentage: https://university.careers360.com/articles/delhi-university-admissions-how-calculate-best-of-four-marks

I Hope this helps!

All the Best

PS: Go for a Hons degree in BSc and not simple BSc :)