See around 70-80 questions surely will be from NCERT only. Of course they will be twisted a but but if you are thorough with the NCERT and your basics, then you will be able to attempt them easily. So the funda is if you are happy and comfortable with scoring 280-310 marks in Biology hoping that you score good in other two subjects too, then yes NCERT is enough. .but if you have time and feel confident enough, then you can go for other books too to score better. But do remember, don't waste the things that you have in respect to get more. Study extra books only if you have time and are finished with the NCERT that's my personal guidance. Rest up-to you.

Best wishes. Thank you.