Each TRTO will produce its own examinations, which are individually approved by the relevant NAA. Some TRTOs sub-contract this task and the GECAT A320 electronically generated exam comes, I believe, direct from Airbus. Other TRTOs have their own electronic systems to set exams but most rely on hard-copy papers.
For a multi-pilot type there will be a minimum of 100 questions distributed across the main subject areas of the theoretical knowledge syllabus (as defined by Appendix 1 to JAR-FC 1.261(a)) and there is a pass mark of 75% in each subject area. For single-pilot types the number of questions depends on the complexity of the type and the pass mark is 75% overall with no requirement to pass individual sections.
I know this because I have spent the last week and a half preparing new papers for approval by the UK CAA - fingers crossed!