always study either ecology or dna as they both come up. also photosynthesis and respiration one of them if not both tend to come up in someway. if im honest im trying to go over eveything but for the mocks i left out almost all plant stuff and still did well, so if you want to take a chance then go for it
Based on Stat analysis on topics and trends: Food / Musculo Skeletal sys / Ear & Neurons / Kidneys w Nephron / TS of dicot stem / Circulatory Sys / Bacteria and growth curve / germination / plant transport / protein synthesis [RNA] ... usual standards also are Ecology / photosynthesis / respiration / enzymes / genetics. That equates to about 16 - 20hrs of good focused study [approx 30mins/day] until 14th June. Keep testing yourself. Practice diagrams. Learn definitions. Good luck!
the way that the paper is layed out this year you are able to leave out 1 unit youre just not gauranteed any choice. Like for example im doing unit 1 and unit 2 and then microbiology which is like viruses fungi proista etc. just to give my self some choice on the day but you dont even have to.