Dear Angam, the basic eligibility criteria for pursuing M.Sc Biology is that you should have completed your Bachelors in any if the subjects like Biotechnology, Biology, Biochemistry, Botany, Zoology, Microbiology, Agri Biotechnology, MBBS, B.V.Sc. The minimum aggregate depends on the Unuversity that you want to pursue this course from. So just to answer your question with B.Sc in Zoology, you can pursue M.Sc Biology.