Hi!
Thanks for this question! It can definitely be frustrating when efforts don’t seem to be reflected in exam scores. We have all been there before. I am not sure how exams will be run in the upcoming semester, but based on my past experience, there are four exams (non-cumulative). The exams are usually multiple-choice and free-response. 
Everyone has different study methods that work for them, but this is what worked for me to earn an A.
1.) I printed out lecture slides (or use an tablet if you have one) and took notes directly on the slides during lecture.
2.) I re-watched most lectures so secure my understanding and review more difficult topics I did not feel confident on. Some weeks I re-watched all of the lectures, other weeks only portions.
3.) I read the textbook after lecture to fill in any gaps in understanding, especially with material I was struggling with.
4.) I went to office hours and joined an SLC! Even if you don’t have any questions, it is a great opportunity for review material and test your understanding by helping explain concepts to other students. The SLC offered me the opportunity to practice explaining concepts out loud to others without my notes. This may help you identify weak points in your knowledge. 
5.) Specific to BIO 172, there are quizlet cards online that can help with memorization if flashcards are your type of thing.
6.) To prepare for exams, I re-did discussion assignments, reviewed lecture objectives, and did practice exams. I also made a study guide that summarized all key points.
The most useful habit I developed was working on a study guide/summary of lectures. I would recommend reviewing lecture material at the end of each week and summarizing key points in a study guide, so that you don’t want to learn concepts right before the exam. Some students prefer to organize a study sheet of key concepts/main points after every single lecture, rather than at the end of the week. I do this for my general science courses and it helps me stay on track for success. I tried to distill the lecture information as much as possible; try to write things in your own words and make connections between topics rather than re-writing lecture slides. This process of active learning avoids the possibility of simple memorization, which is often not enough to earn an A in biology courses. After you make and review this study guide, I would recommend re-trying the discussion worksheet that weekend to confirm you have a good understanding of everything you learned that week. I am someone that struggles with translating lecture material to answering questions on the exam, so I try to start practice questions as soon as possible after starting new material. 
Hopefully you take away from my experiences that active and consistent review is the most important thing to succeed in general science courses. By reviewing concepts and practice problems each week, you can spend the week before the exam focusing on smaller details and test taking strategies.
Best of luck!
– Isabel, PMH advisor