B.Sc

BCA is more Job Oriented as compared to B.Sc in Geography honors.

The first point is that your point of interest towards subject. BCA and B.Sc in Geography both have scope. You may choose any of them.

BE is 4 years degree course and B.Sc Is a 3 years degree course. With BE you will get engineering degree and you can get placed in top Industries if you complete it in top Tier I colleges or Universities. Whereas, B.Sc is for those who can't do BE programmes, as the eligibility is quite low or those who can't afford to pay high fee for BE, placement wise it would be quite less and have to pursue a Master degree to get better opportunities.

Yes, you have to attend the classes because attendance is compulsory. You should have 75 percentage attendance to sit in the exams.
Good luck.

You should practice more questions and solve previous year questions. Also, you should revise you class 11th – class 12th concept.
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If you come under category, then there are chances that you can admission in DU. Otherwise, there is no chance of getting seat in DU. Good luck.

Yes, you can apply for this course.
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Yes, you can apply for this course after class 12th.

Maths would be required to get admission in engineering college as well during course. But if you go with B.Sc in biotechnology, then Maths is not at all necessary. Yes, maths is very much necessary for a biotechnologist, biotechnology is a vast field. It is a study which combines biology to technology. For computer Science, having studied Mathematics, one language and two other academic subjects are necessary. For Mathematics Statistics, 50% aggregate marks are a must. Maths is also compulsory for B.Sc (Hons) Bio-Chemistry are Physics, Chemistry, Mathematics and Biology or Bio Tech. Thank you.