Bio Engineering
Both are the good options & colleges. It depends on your interest & capability. The difference is only that Biochemical Engineering is a professional Degree & B.Sc Zoology is only Graduation degree. So you can choose as per your interest.
These both are different domains of education. You seem to be interested in computers. For that maths knowledge is beneficial.
To get admissions in BCA shall be difficult without Maths.
Or else you can study Maths from external board so that you become eligible to apply in Computers.
Any other
Manufacturing engineering has better scope than Biotechnology. Choosing a branch depends on your interest every branch has good scope it depends on your caliber.
If you have taken admission you don't have to worry about that just give your best.
Good Luck!!
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