You only have to remember a few quotes.
I read this essay just the other day, and it had like a 5 line quote in it. I was like WHOA! (the person only got into the midrange)
If you use quotes that are too long, you lose your audience as they forget what you're talking about. Remember, the people marking your HSC is doing about 25 papers an hour, if they're side tracked by a massive quote, they're not going to read it over again and you will lose marks.
Also remember, because they're only reading the essay once, and not so carefully, you can make mistakes. If you can't remember an exact quote, remember about what they said and make something up. Even if they notice, it's not like they're going to go over the book again in detail just to find one quote mentioned in your essay.