National 5 Graphic Communication prelim 2019/2020 Watch
it had bar and pie charts so you need to know how to read them, it had a question on line types where you had to identify the different types so you'll need to know the differences between them (hidden detail, centerline, outline stuff like that), there was a question on building drawing symbols and identifying them, I can't remember all of them but I know one was 'existing tree- to be removed' and another was 'shower tray', you'll need to know direction for a question on which way a window is facing, it also had a 3D CAD question where you have to describe how to make a base of a candle holder and then a question on how to constrain all the pieces together, there were 8 marks about colour where you need to write what colour gives off the emotion of 'anger' and what colour can represent 'environment' you needed to know a colour that is opposite yellow on the colour wheel (purple) and you needed to know the two tertiary colours that feature red you also needed to know how to make either tint or shade. There was a couple of pages on DTP, one was labelling different elements on a page.
I have a pretty bad memory when it comes to exams and prelims so that's all I can remember, for now, basically, there was everything in the prelim so it's probably best to revise it all, try past papers, especially the ones from the last 3 years they really helped me and showed me what I know and what I don't so I knew what I needed to revise more.
hopes this helps!