I will be completely and utterly honest with you, the 1/2 course is junk. Unit 2 has 1% relevance, and as for Unit 1, yeah like 40% is relevant. BUT it does not go into nowhere near the amount of detail the VCAA expects from you in 3/4. In Unit 3 we learn: Biochemistry, Cell Resp. (in detail, quite complicated) Photosynthesis, Endocrine (hormone) system, Nervous system and Immunity. Biochemistry was not covered, cellular respiration and photosynthesis were talked about, but really what was learnt in unit 1 was just what went in and what came out in the processes... VCAA expects you to know each of the complicated stages inside and out if you want A+ marks! Endocrine and nervous were hardly covered (if at all) and Immunity wasn't touched. What a stupid course outline, honestly, for 1/2 to have so little relevance, I got A+ on my Unit 3 2012 midyear so speaking from experience... the amount of detail required in 3/4 is like 10X the amount in 1/2 #wasteoftime. If you summarise well, do as many exam-style questions (checkpoints and as many past papers) you'll be fine, I know people in my class that got A/A+ grades without 1/2. As you can tell I feel very passionate about how useless Units 1/2 are ?