AQA Chem6 ISA - can anyone explain where the marks are allocated

Hello! Just looked through a past ISA, paper. I se 8 marks are allocated to the task, and 30 to sections A and B on the exam paper..that adds up to 38...so what are the remaining 12 marks allocated for? What is a PSA? Do yo u get marks for actually doing the experiments?

Yes, 8 of the marks are for the PSA

But then that won't add up to 50! Surely it's 12 marks for that then?

Oh, no sorry, I meant 12.