This section of moodle has good links and extension materials it is useful for students wanting to do Biology at university, those aiming for higher grades. It also has useful links for IB students doing IAs or EEs.
This is the IB core materials. Here you will find sources,support materials and links which relate to the core topics common to Higher and Standard Level biology. (Chapters 1-6)
There is also the AHL (chapters 7-11)
This is where you will find IA guidance.