Hi everyone,
The assigned "AAMC Question Pack" questions are the question packs under "Practice Products." There should be two question packs for Biology (vol 1 and 2) and CARS (vol 1 and 2), one for Chemistry, and one for Physics.
No Dana, the MCAT Official Prep Sample Test is a full-length exam that you could write later in your study period, around a few weeks or so before your MCAT test date.
From what I know, there's no way to simply pick and choose assigned questions from the question pack. Unfortunately, you have to skip the unassigned ones before reaching the assigned questions. My advice is to create an Excel sheet or Google sheet prior to performing the assigned questions, as this will allow you to better track down the questions that you answered. If a question pack has 120 questions, in your spreadsheet you should also have "boxes" numbered 1 to 120.
After answering a question, highlight that box. For example, you answered questions 1 to 10. These numbers' boxes would be highlighted. The next time you use the question pack, you'll know that "question 1" is technically question 11 because you know that you already answered the first ten questions (since they're highlighted in your spreadsheet).
Yes, I know it's tedious but it pretty much the spreadsheet helps you track down your progress. You can even highlight question boxes with red, for questions that you struggled with or gotten wrong.
Hope these help!