Hi there.
You can surely apply for all medical entrance examinations after completing your graduation course i.e. as mentioned here B.Sc in Zoology.
For being eligible to write NEET one has to be between the age range of 17 years - 25 years (for general candidates) with 50% aggregate marks in Class XII boards with Physics, Chemistry and Biology as the subjects.
It would be best for you to prepare for the NEET examinations during your 3 year course of B.Sc.
Not only that, you can appear for NEET while doing your B.Sc. But once you crack it and get into a medical college you won't be able to complete the B.Sc course. You can only do one thing at a time, either a medical course or B.Sc.
For more relevant information on the eligibility criteria kindly refer to the following link:
https://www.google.co.in/amp/s/medicine.careers360.com/articles/neet-eligibility-criteria/amp
Wishing you luck!
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