It really depends on how much you currently know, which exam, and various other factors. In any case, however, you might as well go for it and see how you do.
It probably depends on how much work you have done throughout the year, your current level ofd knowledge, if the exam is on topics you have revised, your time managemetn skills, ability to cram etc. I would say it is unlikely, but you need to make the best of the time that you have left. If it dosen't work out, you can always resit, but this should be a last resort.
It certainly is possible, well considering i got a B in economics with 2 days revision and no previous revision what so ever, however as brown said its not adivsed...but it certainly is possible! Although to gain that grade in one week may mean working very hard...im trying to get an A in AS Bus Studies (on monday) my revision started 5 days ago, so just under a week...If i can do it so can you
as long as its actually 'REvision' and not 'vision'! when u see it all again it should all come back to you, then you can focus on the stuff you don't remember as much
Seriously though, I'd say you need to have a decent grasp of the module already to get an A in that space of time. It's very possible though. Just requires discipline and a hell of a lot of work.
it all depends if ur learning 2 essays i wud say u cud do it, law for example. i did that for as law exam and got 120 out of 120 on revising jus the weekend be4 the exam