It depends on what you are studying in your class. Some things are much easier to study for than others. For example, if you needed to be able to idenify the various bones of the body, you could try to employ mnemonic devices to remember them all. One device that anatomy teachers use to teach students how to memorize the 12 cranial nerves is this:
On old Olympus towering tops a fat armed German viewed some hops:
Auditory (Sometimes callled the vestibulocochlear nerve)
Spinal Accessory (Also called the accessory nerve)
Sometimes the only way to study is to simply knuckle down and get a handle on the concepts. For example, if one were studying the Kreb's Cycle, one would have to know the beginning compounds; their end products and their quantities; the compounds produced along the way; the enzymes invoked along the way, etc. Some things are simply easier to understand and recall if we make sure that we understand the process as it is occurring. The way I would often approach something as complex as this, or meiosis, is to simply look at the big picture first. Then delve into the details of each stage of the process and memorize and understand what is happening in each stage. Then build a complete picture in your mind of the entire process being fit together, like a jigsaw puzzle. It often is a good idea to draw diagrams as you work through the process to make sure you understand everything, and get all the parts to fit together properly.
Another good way to study is to memorize facts, names, etc, by writing them down over and over again to impress them upon the mind. I studied that way often for my Latin vocabulary quizzes and tests in high school, and I usually did extremely well on them. This method is called inculcation.
Looking back on my biology education now, I understand that I had a serious advantage over other kids in high school and college. I aced my high school biology final (96 out of 102) and also did well in my college biology courses. It was only a few years ago that I learned through my genealogical research that there were many doctors on both sides of my family in my ancestral background. There are about 10 in number, including one great-grandfather, whose uncle also numbered among them; two-great-great-grandfathers, one of whom had several brothers and a son in the profession (the other was a Confederate Army surgeon), and numerous others whose relationship to me I can't recall at this time.
Here's another idea. Ask your biology teacher what would be a good method for studying the particular material that will be on your test. As a former biology student himself or herself, they should be able to give recommendations, especially on material they are teaching and are familiar with. When I was in school, it amazed me how few students availed themselves of this important resource.
Good luck on your exam.