As per the JIPMER PG entrance is concerned, you can go thoroughly the NCERT books and the subjects to given importance are anatomy, biochemistry, toxicology, pharmacology, physiology, forensic medicine, pathology , microbiology for basic clinical science. It is going to be a 1000 mark exam with 250 questions and time duration is 3 hours. There will be two topics that is basic clinical science from which there will be 150 questions comprising 600 marks and clinical science having 100 questions making it 400 marks . Solve previous years questions to have a keen knowledge about the question pattern. It will give you confidence to appear the real test without much difficulty.
I hope this answer clarifies your doubt.