I wont to do PHD in Biology. What i need to do after 12th.
Good luck !!!
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