What is the target audience for Socratic? It appears that it's for High schoolers and Undergraduates. Would this be a good place to ask questions on more advanced areas (eg. developmental biology), or is that outside the intended scope of the website?
You should definitely post questions on more advanced ares on Socratic.
There are a lot of professors, active or retired, that contribute on this site, so there is a possibility that even advanced questions can get an answer.
For your example, I know that many contributors to the Biology page are currently active in different industry fields, so you can get to interact with professionals as well.
The bottom line is that you can try and post any questions you like, who knows, maybe someone can help you with an answer.
For very advanced topics, like research and stuff like that, you can always check out ResearchGate.
As far as I know, it's one of the biggest, if not the biggest, online community for researchers and scientists, so you're bound to get answers to very advanced questions there.
Here's a link to their Wikipedia page