Unfortunately with this subject you do have just got to use your English skills as well as chemistry or biology essay skills.

Write at least two sides using your notes and then do exactly the same without trying to remember the content of the last one. then rest for an hour or so then without looking at notes or the previous two essays try and write the essay again with as much facts and figures as possible

This is what i tell my students they hate it (lots of work) but if you do it for each of the core units and sub units i think you are set to go into that final exam and get a good grade.