I'm a second year at the moment, and found studying for first year biology to be quite different to second year, as it's a bit of a broad introduction to so many different areas within the biological sciences.
I was initially similarly frustrated by the lack of past papers as a way to test my knowledge, but eventually found that the reason for this was the reason that it actually isn't that hard to study for - they simply want you to know the content! It sounds stupidly obvious, but it is different to the more 'applied science' approach you might have taken in Year 12 studies or equivalent.
I took the approach of summarizing and summarizing until I had maybe 15 pages of 'key topics' and the bare bones of what we had to know about them - knowing every definable word etc. This basically gets you through Multiple Choice.
Section B in first year Bio (labelling diagrams, tables etc) is often taken straight from diagrams in the lecture notes. I found that any diagram that looked slightly complex was a sure thing on the exam at the end of semester. For the rest of section B, my basic knowledge of the whole course from learning the summarised version of things was more than enough to put the pieces together.
I found that Section C of the first year Bio exams, which involved more essay or extended response questions was the only part in which more in depth knowledge was required. In saying that, many of the things you had to expand on were verrryy basic (e.g. describe meiosis or thermoregulation) and therefore you should be able to manage decent answers without memorising every detail of the lectures.
Overall, my impression of first year bio in particular was that it was almost like a breadth subject - more about being across a number of different ideas and concepts and understanding the links between them than looking at any one thing in greater depth (as you will in later years). I would encourage taking a holistic approach when thinking about what is important to memorize and understand, rather than worrying about every detail of every lecture.