YMMV but I was actually asked pretty surprisingly specific stuff about my research. Like, discussion of the pros and cons of the cellular disease model my lab uses, specific info about my methods for one of my experiments, etc. But, research has been my full time job for several years, and the interviewer in question was a biochemistry professor, so I think it probably just depends. I think if you have a good understanding of the type of research your lab does, the level where you can have a discussion about the goals of your research and the problems that come up (like beyond just being able to say that you ran PCRs) you should be fine. Know your role in the research project but also be able to discuss the big picture.