B.Sc Zoology

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.

Candidates who have completed a higher degree in any discipline from any UGC/AICTE recognized institution in India or abroad with the required percentage are also eligible for the course.
Final year appearing candidate can also apply on provisional basis.
SC/ST candidate must have secured passing marks.

Go through the detailed BHU PET eligibility below:
https://www.shiksha.com/university/bhu-banaras-hindu-university/bhu-pet-exam.

It is approximately 25,000/- per year.
Good Luck!

Hi, Please find the link below for detailed information:
https://www.shiksha.com/science/colleges/distance-correspondence-m-sc-colleges-india.

Hi Puja,Yes ofcourse, you can do M.Sc in criminology in UNOM.