Hi, year 12 who did AQA last year. I've not heard anything about quoting the line so personally I would play it safe and write the specific/short quote you want to write about, to get straight to the point.
If you're trying to fit in a big quote from a whole line, you can always pick out what you need with an ellipsis, so you could do 'Adjective 1... Adjective 2' if that helps.
One more thing - the examiners want you to do well so will mark less harshly than teachers who know you. So you'll most likely do better in the gcse than your mocks. If you can find the quote in the first place you're off to a good start.
Good luck!