Hi Subham,

For completing B.Sc., in Zoology, there is no necessity to take up physics. There is no college, that offers physics as an extra subject in the course time of Zoology graduate studies. Even if any college does offer physics, it would be an optional course (Like in Liberal Arts). 

If you are a high school student and wish to pursue B.Sc., Zoology, then you can drop physics in high school and opt for a pure biology related group.

All The Best.