Hello,
The most preferred exam will obviously be CSIR-NET Exam, this is recognized amidst all the renowned institutes as well. The exam is conducted twice, in the month of June and December.
GATE exam which is conducted once every year in the month of February, by seven IITs and Indian Institute of Science. This score is valid for 3 years and you can apply for PhD programme in the mentioned illustrious institutes.
Joint Graduate Entrance Examination for Biology and Interdisciplinary Life Sciences (JGEEBILS) is entrance exam for PhD programmes, institutes like IISc, IISERs,NCBS, TIFR recognize scores of this exam, however after qualifying this, you need to apply separately for the above institutes.
Apart from the above mentioned ones, you can also apply in the following entrance exams-
AICE JRF/SRF(PGS)
ICMR-JRF Exam
DBT-BET Exam
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile