My test had a LOT of computational problems (PS) and confusing genetics problem (BS) that required lots of paper... for me at least. And yes, you can get a new "booklet" of scratch papers at the end of each section, as needed, during breaks!
Since everyone's been using tons of scratch paper. i found these scratch sheets very useful. instead of using 300 pices of paper I bought 5 of these http://www.scienceaide.com/scratchsheet.php?thumb=blank and Ive been using it for more than a month now. Def better than a lot of paper on my desk.
These would be good to get used to especially if this is how the test site does their scratch paper. The one I tested at used real paper and pencil though, so that's what I practiced with.