given it more thought now...
basically fine for writing down stuff you use right at that moment, like diagramming an experiment or writing down key words........ BUT, i think if you write down that question #17 was amino acids and it was tricky, that info will invariably smudge before you get back to it.
you can highlight Q's to come back to on the computer but it would be nice to have a little note appended, like a few words as to what it was.
and don't erase stuff by hand. that will work but then you'll have sweat on the board.... don't be shy about asking for a new board.... for whatever reason ("anxiety", "you're not supposed to", "don't want to flip through the boards"), it is very tempting to erase stuff by hand. DON'T