The questions in the full length are all sourced from the tests in the subject tests. They are not different questions. They just link the subject tests together. To simulate a full length, you would take the Writing Test #1 and once it is over, then you launch the Biological Processes Test #1, followed by Chemical Test Processes Test #1. Then take your break. Followed by Critical Reading Test #1 and launch Quantitative Reasoning Test #1.