Many students find studying science at the college level more difficult than they anticipated. Typically the study skills and techniques that worked in high school are inadequate for college-level success. For a typical college class you should study two hours outside of class for every hour in class. You can't cram all of that into the week before the test. So, study every day.
Attitude is half the battle.
Sure, there's a lot of material you need to know, and it would be easier if there wasn't so much to study. But your goal should be to understand biology, not to make studying easier. Listening to lectures is passive. If you want to learn the material you have to take an active role - you can't just sit in class and expect that by some magical or miraculous process someone can teach you. Sometimes you're not quite sure what to ask.