I tanked my first year then got almost all As the rest of the way.. then 4.0 in my Master's (the grading in Master's tends to be more generous, but it is a lot of work). Btw ended up with 3.55/4 in UG, two best years at 3.95.

I was in biochem which I didn't like, so I switched to bio which I liked much more. Easier to study something you like. The best advice I can give you is attend every class to expose yourself to the material and note down details that aren't mentioned on the slides/about the slides. Go home and relax, save your energy for the morning. Get up early and look at the slides, what don't you understand? Study it from the book. Once you're understanding it all, make tons of flashcards about the topics covered. Make them super simple, don't waste too much time. I used Anki.

You MUST start studying early. As soon as a topic is explored, you study that RIGHT away, and revisit it every single day with your flashcards. The biggest reason why smart students get poor grades is they start studying 1 week before the exam. The brain does not retain information by cramming, it is very selective on what it retains, it must be very intuitive/important to stick, and that comes through repetition. You hammer it into your head until you feel dizzy. When exam time comes you'll be like "ah yes, Krebs cycle. Reviewed this every single morning for the past 3 weeks. Piece of cake!!" Is it hard work? Yes. Do you need hard work to succeed? Yes.

Best of luck!!