Immy is correct, you need to be able to do scales and arpeggios in all keys. The syllabus for grade 8 violin is
here . The relevant bit is
QUOTE
SCALES AND ARPEGGIOS*: from memory, in the following keys:
Eb, E, F, F# majors; Eb, E, F, F# minors (two octaves)
All other keys G–D inclusive, major and minor (three octaves)
Good luck with your exam.