Depending on your exam board you'll learn different things. I do AQA philosophy A level and I really enjoy it! It's one of my favourite subjects to learn about and philosophy is so useful in so many different areas. Our four topics in AQA are epistemology, which is about knowledge, moral philosophy (self explanatory), metaphysics of God, where we essentially explore arguments for the existence of God and look at whether the existence of God is compatible with the universe, as well as whether religious claims can mean anything, and lastly metaphysics of mind, which looks at whether the mind is a separate entity and whether there is a world that exists outside of the mind. You don't need to learn quotes but it can be useful. In moral philosophy particularly, I find it a lot easier to memorise quotes from philosophers, because they are so well known and fit in with their moral theories (e.g. Kant's first formulation of the categorical imperative). You'll need to memorise arguments and pretty much anything on the specification, however for AQA there isn't actually a lot of content, which I quite enjoy since I take two other essay based subjects with lots of content (politics and psychology). Since the specification was revised in 2017 and the first papers were sat in 2019, there are very few past papers available online, but since there is only so much they can ask you, revising for philosophy in my opinion is much easier than most subjects. The difficulty is with precision - you can lose marks for redundancy and inaccuracy in philosophy, so basically don't waffle too much. In AQA philosophy we have 2 papers: paper 1 is on moral philosophy and epistemology and paper 2 is on metaphysics of God and metaphysics of mind. They are both 3 hours long and the total marks for each paper is 100, with each section being worth 50 marks. In each section, you will be given a 3 mark question (usually a definition), two 5 mark questions (can be arguments, criticisms, defences, parts of a theory etc.), one 12 mark question which is essentially two 5 mark questions put together with an extra two marks for linking back to the question, and a 25 mark essay question. The 3-12 mark questions are all about content that is on the specification, so it is only AO1 marks (knowledge and understanding). The 25 mark essay will require you to give a judgement on a theory or argument, with AO1 being worth 5 marks and AO3 (your explanation of problems and judgement) being worth 20 marks. Your opinion counts a lot more in philosophy essays, which will contrast nicely with your current combination of biology and chemistry. I actually wanted to pick the same subjects as you before sitting my GCSE chemistry papers, but quickly changed my mind and ended up with psychology, philosophy and politics. However, if I had stuck with your biology and chemistry, I think picking philosophy out of my current subjects as my third subjects would have definitely been the right choice. Again, the content you learn will depend on your exam board, as I know other exam boards have a lot more content in them than AQA does.