Dear Roshan

Taking biology in 10+2 is not compulsory for pursuing biotechnology engineering in most of the college  . But if you'll have it then you'll be benifited during the study of the course. 

But for bsc in biotechnology , biology is compulsory whereas for B.Tech it's not strictly required. 

Hello Roshan
Yes, it is indeed very much important to have biology as either core or optional subject in 10+2 in order to do Biotechnology Engineering.
Many colleges now-a-days offer Biotechnology Engineering but all of them has this specific criteria that the candidate needs to study Biology in 10+2 because entire course is focused on Biology.