Basic questions and look over your primary application to see if there any potential weakness to be able to address. Since it's open file, they will point out stuff that may seem like a weakness or clarification. Example, I took MCAT twice with improvement on the second try and they asked how I achieved a higher score. I also had some research experience and they asked what it entailed. Overall, I would say everyone's experience is different and it's interview dependent as some say their interview was conversational but I felt as though mine wasn't.