Biological Sciences is the general major where all accepted students take the same Pre-req courses and then you pick your specific track where you would take those specific upper division classes.
Here is the link of the required classes for all Biological Sciences majors: https://cnasstudent.ucr.edu/files/Minimum%20Progress%20Criteria%20Biol.pdf
And then if you want to specialize in the Biology track, you would take those classes listed under Biology.
https://cnasstudent.ucr.edu/files/BIOL%20Track%20Worksheet.pdf
If you decide on Microbiology, then you take those specific classes or one of the other tracks.