I would like someone to comfirm that we do need to observe the Scherzo D.C. marking in the exam. The Scherzo has 4 pages. Will the examiner practically listen to the full repeat?

Page 21 of These Music Exams states that 'Da capo and del segno signs should be observed as they indicate repeats that are vital to the structure of the piece...'

But bear in mind (and inform the candidate) that an examiner has the option to stop a candidate during very a long piece if, in his or her judgement, they have heard enough to form an opinion.