Twenty five multiple choice questions in three parts. Answer every question, then submit to see your score, your strongest and weakest topics, diagrams of each stage, and what to study next.
This is a diagnostic. Its job is to find out what you actually know before the quiz, while there is still time to do something about it.
The quiz will not be these exact questions, but it is built the same way and covers the same ground, so a weak topic here is a weak topic there. Part 2 is the closest match to what the quiz looks like.
One warning. This practice is a map, not the whole territory. It cannot cover everything from the unit, so use it to decide where to spend your time, then study from your notes, the slides, the model tracker, and the two labs. Scoring well here means you are on track, not that you are finished.
You do not have to memorize these. Nobody is going to ask you to redraw one. What you do need is to read one and say what is happening: where a molecule came from, where it goes next, and what breaks if one step stops. Open them any time while you work, or close them and test yourself first.