It depends what you want to do later on really. I chose English Lit, History, Chemistry, and Biology but I also had a choice to make between one of the sciences and Maths. I chose my mix to keep doors open and out of interest. There is no point doing an A level you won't enjoy as much since you won't be motivated to do well. I'd say choose Biology. Just because it looks a strange choice doesn't mean you shouldn't do it, it just means you have a more interesting set of A levels, and a bit of variation in the type of work you get is good in breaking up the monotony.