Question about AP Exams

Hey guys, quick question:

Do AP Exams have an experimental or variable section like the SAT?

The only reason I am asking this is because, for instance, on an AP Bio practice exam I took, there were 53 MC questions whereas the real exam has 68 questions. I know that for SATs, the CollegeBoard releases practice exams with the number of questions that actually count; does the same go for AP exams?

Thanks!