I think topic 3 will be quite big of a topic e.g. acrosome reaction, Epigenetics, something on protein structure from topic 2, light independent reactions for photosynthesis, succession, time of death, structure of heart, cardiac cycle, HIV, Xylem and Phloem and Immunity (the topic 1-4 bits will be spread ovethe papers tho) I'm sure others will come up but this is my prediction