Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Abhijeet Gaurav
11th & 12th NCERT are good enough. Focus on continuous revision. But for more assurance you should follow Pathfinder Life Sciences Book. That's a very good book for competitive exams & has precise points and clear cut concepts. You should solve questions related to the topic from Pathfinder MCQ Book too that will assist you & will help you establish your concept. It will even let you know your weaknesses. All the Best.