B.Sc Zoology

Hi Mithuna,
No entrance is required but they have specific deadlines during which you must apply. Check here:
http://www.india4eu.eu/applications

In civil services, you will have to take subject papers for IFS botany, zoology and biotechnology subjects are eligible. So, it does not matter in that case, in fact if are preparing side by side it will boost your preparation as subjectivity matters.

He is eligible for M.Sc Biotechnology in well reputed universities like Nirma University, VIT-Vellore, and SRM- Chennai, if he passed entrance exam which is organized by these universities. Although, he can also apply for IIT JAM because some IIT institutes offer biotechnology courses and M.Sc. Ph.D. integrated courses, for those students who have completed their Science graduation without Maths.

According to your score and percentage the colleges under DU will be perfectly fine. So you can try applying under DU to get admission.

Delhi University, IPU and some private universities like Amity University are the good options to pursue B.Sc.

If you have good grades in 12th, you will easily get admission there. Just calculate your best 4 and check whether you are eligible for the courses by seeing the cut-off on the DU official website (or check if any entrance test is there for the courses you have mentioned, on the official website of DU).
The fee is very less since they are government colleges.

Apply for DU in June-July when registrations start. It offers B.Sc in Botany and B.Sc in Zoology.

Yes, you can. But, I don't think you can do all the three courses together, because geography doesn't belong to the biological side. But you can do Botany, Zoology and Geology. It will have high value.

You should do B.Sc (Hons) in Botany. It has good future prospects.

You need to have a Bachelors degree in respective subjects like Botany, Genetics, Biochemistry, Microbiology, Genetics, Biotechnology, Life Sciences, Molecular Biology and Biomedical Sciences in Science stream. So, yes, you are eligible to apply.