So it's pretty much an unwritten rule at least in biology departments in the USA that when a student is defending his or her thesis/dissertation that they provide some sort of food or refreshments. There has been at least coffee and pastries provided by the student for their committee and audience at every defense I've ever attended.
My question is, how often do students do this for qualifying or comprehensive exams? Since they are private I have never attended one to know... Would committee members expect at least some coffee?