A lot of the questions that are asked during an interview for a postdoc position are easily predicted ones. "It is highly worthwhile spending some time before an interview preparing some sample questions and answers. Doing this combined with some investigation into the research group and PI can really give you the edge in securing the position," writes Ellen Moran at Bitesize Bio. Some places, she adds, may even send questions ahead of time to prospective postdocs.
Moran lists a number of questions that she's encountered and most of them are straightforward — candidates should be able to articulate what their career plan is and describe the sort of research they've conducted in the past, including what techniques they are familiar with.
She does, though, offer tips for the tongue-tied. For example, if the position is an academic postdoc, she writes that candidates could say: "This position will allow me to build on my existing research skills and allow me to develop as an independent scientist by acquiring new techniques, additional project management skills, publications and funding grants."
In addition, Moran notes that if candidates have gotten to the interview stage, they've already impressed the interviewing panel. Further, she gives this reminder: "At the end of the day remember you are interviewing them as much as they are interviewing you." So also be prepared to ask, as well as answer, question, she says.