All India Institute of Medical Sciences, Delhi

Hey Shuvam!
For admission in St. Xavier's College, Kolkata with B.sc Honours in microbiology, you must have Mathematics as a compulsory subject.
Kindly go through the link of eligibility criteria
http://www.sxccal.edu/admissions/SXCAdmission2018/UG8102/EligibilityCriteria.htm
I hope this helps.
AIMS PUNE admission procedure:
https://www.google.co.in/url?sa=t&source=web&rct=j&url=http://www.aimsinstitute.in/admission_details.html&ved=2ahUKEwjzkI3z44rbAhXZXSsKHV0zBR8QFjABegQIBxAB&usg=AOvVaw1eZhdLNBZb9OtnWVd8CcgI
AFMC admission procedure :
http://www.afmc.nic.in/#nogo22
Good luck Shuvam!

No, JIPMER does not accept NEET score. JIPMER has its own entrance exam.

Interested candidates are able to apply online from the official website as per the schedule. Candidates are advised to check the eligibility criteria before applying. Admission will be based entirely on the basis of performance of candidates in the Entrance Examination to be conducted at Delhi/ NCRand dates are given below
registration -23 March 18
last date 2 may 18
admit card -16 may 18
Exam date- 2 June 18

They conduct an entrance test which probably takes place in the month of February. There is no system of direct admission.