I found college quite a bit different and more difficult from high school. I was in a professional program and almost every class was a high gear science one! I had the most trouble with physics!
Also the "teachers" in college are not licensed like school teachers are. Many have never had "teaching courses", and they can be dull, uninteresting, and not convey the subject well.
My first Chem classes had horrible professors...just horrible.
When this happens, you are on your OWN!

I think many students run into this adjustment problem.

What I did was psyche out each professor/or instructor and that helped alot. Notice what the teacher seems really enthused about and study THAT more for tests ... it always worked for me.

Our "biology" was divided into Botany and Zoology, one semester of each. I loved those the best, as they were my main interest.