The hardest thing about Biology, when answering examination questions, is the structure of your answer. As a teacher, I see too many times where students write an answer that plays too much "guess what is in my head". As the person marking the exam/test you know the students would know what they were talking about if you could talk to them but because you have to go by a marking scheme, if parts, keys words etc are missing then a student can get zero for the question. Reading from a wide variety of texts is good so that you can experience different examples explaining the same concept. Being able to sit down and explain a concept to someone (like your mum) who doesn't know anything about your topic, but at the end of your conversation does understand, is also good to test your understanding. Doing many practice exams and get your teacher to mark it because students always mark themselves too easy!!! He/she can also criticise how you are structuring your answers. Read the VCAA examination assessment guides for each exam. In my 15+ years of teaching I still think that my students under use me with regards to prac exams etc.