Hmmm… that’s not easy. Because what you want to do, ideally, is test whether the candidate can think logically and critically, rather than test his or her knowledge. So a question like “Why does DNA polymerase bind to DNA but not RNA?” is not necessarily a good question because, to some extent, prior knowledge can help the candidate, but you don’t want to test memory (at least not mainly).
Here, we give all the candidates the same scientific paper (can be from a very different discipline!) to read and then answer questions about it. That discriminates people quite well i think.
I’m not a biochemist as such and have never done a biochemistry interview, or an interview with any particularly great questions as such. I’m also not in the position to interview people at this stage so I’ve never interviewed anyone. I asked around some biochemists that I know and one said this would be what he would ask:
If you have two tubes- one with protein and one with water, and I ask you to tell me which is which without adding anything or opening the tube, how would you do it?
But it does require some knowledge and a lot of people around couldn’t come up with many things. So, I wouldn’t expect you to be asked questions that require prior knowledge. A scientific paper or article would probably be a good way to go.