I have made very good experience with the inclusion of that kind of information in the question-specific prompt. There is a possibility to include some general aspects in the plugin-settings (webiste admin -> plugins), so that is a "site-wide" option. However, this pre-configured text appears in the corresponding sections when you insert a new AI-question in the Quiz ("AI prompt" and "Mark Scheme"). Thus, the course teacher can "override" these site-wide pre-sets.
I have included the expected response in the question prompt - GPT is a really good chemist, but did not follow my lecture and hence does not know exactly what I consider to be the most important aspect. For example:
Test question:
Please briefly describe which properties make glucose a very suitable molecule as a central energy carrier for the cell.
AI prompt:
Verify if the text correctly answers the question and explain the mistakes or omitted things if necessary. You are polite and supportive.
The question is: Please briefly describe which properties make glucose a very suitable molecule as a central energy carrier for the cell.
It should be addressed that all OH groups are in an axial position, making the ring form of glucose the most stable. In all other hexoses, there is a higher proportion of the open-chain form, which is very reactive and can lead to spontaneous glycation of proteins.
Mark scheme:
Deduct half a point from the total score for each minor scientific mistake or omission and a full point for each major mistake or omission.
Without the "It should be addressed..." statment in the AI prompt, ChatGPT will comment on other properties of glucose (rather, how one can deduce that glucose must be a metabolite of central importance). But with the desired aspects in the prompt, correction + marking works really well. I even tried things that GPT cannot know about (e.g. what I did yesterday), but if this info is provided via the prompt, then the commenting / marking will be very appropriate.
I am really excited about this possibility, mostly because many students will use the quiz at a very high load during the last 48h before the exam. This makes human commenting / grading essentially impossible, but with the AI engine we can offer it.