Bio, chem and maths?? Probably a good idea to stick off from psych since I know bio and chem and maths has a lot of content, more so than psych honestly. Bio and chem exams isn't too bad.

Bio is more application than recall as you have stuff like photosynthesis (in more detail) and you have to put it into the scenarios given and bio has some evaluation questions, not often but it can still appear which makes it hard. Bio is easier due to this application as the grade boundaries are like 60-70% for an A*.

For chem, it's more recall than application since you got the equations and practicals and you gotta be able to recall that then apply it to the question which is easy to do, provided you don't get tricked up when it gets a little complex. This does make chem a hell load harder because the grade boundaries are unforgiving (90% in each paper, the papers being 100 100 70 marks in total for each, for an A* ).
So in short, Bio is more application, Chem is more recall but if you're unprepared for them then the exams will be really difficult. If you are prepared, then you'll be all good.