Hi Manjula.

If the entrance exam is for B. Tech or M. Tech., then yes, you need to appera for both biology as well as mathematics.

Whereas for B. Sc. or M. Sc. Biotech, you will have to appear for biology as well as mathematics but the maths in this case would consist more of basic maths while in the former it will be of advance level.

But yes, in both cases you will require to appear for biology as well as maths.

Hope it helps.