I'm kinda sliding into your Mind mapping thread, but my own experience is that Biology, more than anything else I've study is a progression of linked knowledge. It is a pile of facts that can be overwhelming. In biology it is hard to see how one bit of information gives rise to another, which is one of the charms of math based sciences. However, I've always found linkages (need to know) / (detail of understanding) / (explanations of causal effects) with biology. And as such it just becomes one body of related knowledge, or one big Mind map if you will.
In my experience other sciences lend themselves, more naturally, to a linear exploration / explanation. For me the trick to biology was about the connections or layering of detail.
Good luck,
Iam2 
