Got an A* in the B3 exam (biology triple science), mock grades were Bs and As, then got a D at AS. Dropping it for another subject, wish I could say it was down to lack of studying. Biology is called the easiest science A Level but it is far more difficult compared to non-science A Levels. The content is relatively fine but the exams were horrible - you also need very good maths. It just wasn't for me I guess.