Dear Tanya, For NEET, having a good grasp over the NCERT textbooks is a must. All the topics will be from NCERT only. But, while you practise MCQs, you will find that not all answers are found in your NCERT books. NCERT books have all the topics prescribed in NEET syllabus, but everything is explained in brief. So, to be able to answer all the MCQs is NEET, you should be having in depth knowledge on all the topics of your NCERT book.

It is better, if you follow some of your +2 level text books as well, for NEET preparation.

I wish you good luck!