as someone who is now doing a chemistry degree at uni of nottingham i would say chem is harder. did both at a level. I got a C at a level biology with revision just the day before and no sleep as i revised through the night (this is with not attending the course in A2 year) and I got an A(A* in one A2 exam) in chemistry with 2 months of revision, theres still a decent amount of memory work in chem, obvs not as much as bio but it is definitley harder. I'm generally better at chem than i am bio, but revising ONE night and getting a C in A2 bio, well lets just say i ********ted my way through it and i remember making stupid mistakes as well as thinking that the exam itself was harder than most. this was last year btw and i took AQA. so yeah, chemistry is harder, but i think to get an A*- A with biology all you need really is time.but you know, i might be biased . :P