Hardest (or weirdest) question you were asked during your candidacy exam?

One of my Ph.D. students will be taking his candidacy exam soon. This is the exam, also known as "qualifiers" or "orals" at some universities, that tests whether you have the background knowledge to get a Ph.D.

In order for candidacy exams to fulfill their purpose, profs have to ask hard questions. An excellent way to figure out how much a student knows (and to see how they think through problems to which they don't immediately know the answer) is to keep pursuing a line of questioning until you exhaust the student's knowledge. Of course, that's not the only reason profs ask hard questions. One unofficial purpose of candidacy exams everywhere is to let profs prove to students that they know more than the students do. Plus, it's a traditional ritual profs had to go through themselves, and so they're darn well going to make their students go through the same ritual. ;-)

My own candidacy exam actually went quite well. Maybe my profs were feeling kindly that day*, but they never really pushed me to the point where I just had no idea how to answer. The question I remember best is one Peter Morin asks all his students: Name five famous female ecologists or evolutionary biologists and summarize their contributions to the field.

I know of an amphibian community ecologist from Duke whose exam began with one of her committee members sliding the latest issue of an evolutionary journal (which had just arrived in the mail that morning) across the table at her. The cover featured drawings of several fossil fish. The committee member asked, "So, what do those fossils illustrate about fish evolution?"

At Rutgers, one of my friends was once asked, "You're reading a French biology journal and you come across the acronym ADN. What does it stand for?" Note that Rutgers is an English-language university, and neither the student nor the prof knew French. (answer below)

I don't have any anecdotes relating to any questions I myself have asked. For better or worse (and I think it's a bit of both), candidacy exams in my department are somewhat narrowly focused and there are rules to prevent profs from asking overly wide-ranging or off-the-wall questions. So I don't know that any of my students will ever get to have any really good anecdotes about the ridiculous questions they were asked during their candidacy exams.

So what's the hardest (or weirdest, or most memorable, or whatever) question you were asked during your candidacy exam?

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Answer: ADN stands for DNA. Apparently the prof had just learned that the French acronym for deoxyribonucleic acid was 'ADN', and found this bit of trivia so interesting that he decided to ask the student about it.

*Or maybe I had left enough books on my desk that morning. The rumor in the Morin lab was that Peter would come in to your office very early on the morning of your exam, look at all the books on your desk (which you had presumably been reading in order to prepare for the exam), and not ask you any question that you could answer by reading any of those books. I don't actually know if Peter does this. But it does raise the possibility that, if you had enough books on your desk, you could prevent Peter from asking any questions at all. ;-)