
they are evil, but...
Don't forget, they are only two of heaps and heaps of scales, there's no guarantee those two will be picked... and even if they are, your scale grade is based on how you play all of them, not just two out of them.
In my flute exam I was
petrified and had to start at least one of my scales twice (it had never occurred to me to ask if it was OK to play them again, till my friend who accompanied me and gave me a lift to the centre told me so on the way in that morning!), and asked to repeat one of them because it went really badly... and I got 19/21 with the comment "Well known and secure at a suitable tempo. Just the odd small blemish" - much better than I had expected. Having to try again on one or two is NOT the kiss of death for your scales except with a
really evil examiner.
And worse case scenario... your scale mark is only part of your overall mark, and even for "very poor, incomplete response, sporadic and uneven, very slow tempo, technically totally inadequate" the guideline mark is 7-10! I am certain you will play them a whole heap better than that, even those two.
I'm sure your teacher would not have entered you if she(he?) didn't think you stood a good chance of a decent grade, so try not to worry about it
too much, (easier said than done I know!) all you can do is your best. I'm sure you will pass and probably do really well, and even if you didn't, it's not the end of the world and to be going for grade 7 after a relatively very short time playing is really impressive, so just do your best and I bet you will surprise yourself...
I agree... they are evil scales...

but it's only two of them, and even then they are bound to improve by the time your exam comes round.