Snow’s university has a big biology department and several of my Sims study biology there.
For this I am using a modified version of Rachel’s Sims2 university major careers.
As long as the metric smileys are not green, my Sims have to keep studying, with books, skill objects and the Online Center Mod.
When they have got the necessary skill they have to complete a sememster project. For First Semester biology that is to grow their own plant.
If they manage all that before the semester is over, they move on to the next one.