Higher RMPSWatch this thread
For the living by the gospel essay (assuming it's a part of the world religions unit) I would suggest revising the key terms, practices and what it means for people to live by the gospel (basically the knowledge points so you can explain it in detail) and then come up with any analysis points you can use (so what are the implications of living by the gospel? any challenges? strengths? weaknesses? importance? benefits?). You can also gain some good analysis marks by drawing links between topics.
As for the organ donation essay I would suggest knowing the religious and non-religious viewpoints on the matter and the strengths and weakness of both views. Non-religious views are things such as the law or utilitarianism and the religious views are whatever you have covered (I would opt for Christianity if you haven't been taught any). I would also make sure to have some key points on any moral issues arising from organ donation too.
I hope this helps a little good luck for tomorrow!