I think what DVMorBust actually means is that it's much easier to BS an essay-ish type of exam.
Really though, if you know the underlying concepts but maybe not so much of the details, you can still generate a coherent and intelligent response that shows what you know in an essay format. You cannot do that in a multiple choice exam where someone's more likely to ask you something like "What class of virus do the Reoviridae belong to?" with five choices, at which point you had to memorize that class I = ssDNA, class II = dsDNA,
in addition to understanding the general characteristics of the Reoviridae and how they replicate (which IMO is the really important piece of information that needs to be understood). In that case it doesn't matter whether you understand those characteristics or not, only that the one piece of information, the somewhat arbitrarily assigned class number, is going to decrease the chances that you get the question right.
edit: But basically I'm always really annoyed whenever I'm tested on anything that I could plug into google using one word or short phrase and get an answer by looking at the results page without even clicking on a result or reading anything in depth.