Best option to do PhD is to go for bsc in any stream of your choice in biology then do your MSC and then PhD

Good luck !!!

Dear

As per your query and According to me you can consider these options in bachelor

Life sciences
Zoology Hons or Biotechnology

Then after 3 years then you have options in master like

Microbiology
Stem cell
Nanotechnology
Genetic science

When you are in master then you can take guidance from the Faculties to choose the research topic in PhD .

All the best

First bsc, then msc, then PhD.. It's a pretty good career option now a days..