At the end of the day, you’d need to like doing maths to some degree if biology is the degree you want to study. I don’t know exactly for bio, but I have friends that study biological natural sciences at Cambridge, and obviously there is definitely maths involved, for example I believe they have to do a maths work sheet every week. In relation to this, I would say that studying maths at A level would be a lot more beneficial for you than geography. This may only be for certain subjects (for example, I know for law they have these statistics), but on the course’s information pages for cambridge, it will tell you what A levels a lot of the the successful applicants had taken, so this might be worth looking at.
Obviously, at the end of the day, you do need to pick a) what subject a university may require, but also b) what subject you are likely to get a better grade in.
Obviously make sure that no where you are thinking of applying requires you to have an A level if maths if you decide not to take it.