Not doing any good at biology

Hey guys, i’ve been studying the biology from Princeton’s book since last Jan. Now that I am at the final page in the final chapter, I decided to take a bio real test to evaluate all the efforts i’ve done those 4 months. When I began working on the test i was really shocked because I was only able to get 12 out of 25 questions correct (couldn’t wait til getting the test done due to my frustration).

So, has anyone experienced similar situation? Forgetting almost everything on biology when taking a test? Please if you know a way to sort this out let me know, only 1 month left for the SAT biology subject test