Discriminating examination

If you really want to find out how good students are, how well they are learning, how well they are mastering the material, all you have to do is push them just past their comfort zone, stress the system a little, and the results will be very discriminating, and quite discouraging.  My last botany exam covered too much material, that is, too much material to be easily reviewed just before the exam.  Not only that but the lecture material involved a couple of key concepts that are rather beyond a textbook to explain (a classic textbook weakness).  And without any particular intent to create more of a problem, the exam asked students to demonstrate their understanding of the land plant life cycle, a topic the Phactor has been beating his head against the wall for decades to teach effectively.  This subject has the ability to separate the memorizers from the conceptualizers.  Now as freshmen about 70% of college students are memorizers (concrete thinkers) and 15% conceptualizers with the remaining 15% sort of transitional.  By the time they get to be 3d and 4th year students you certainly expect a larger percent of conceptualizers, but my class breaks down almost exactly like 1st year students which indicates that we, a collective we, are doing a very poor job of changing the way they learn.  From the view of the concrete thinkers, the Phactor is a poor teacher and gave them an unfair exam.  However at the other end of the class, the exam was considered easy with two nearly perfect papers (out of 22).  The Phactor was unaware of how drastic the problem was because it was not readily apparent until the system was stressed by the amount and nature of the material covered.
Here's an example.  The diagram is a typical moss.  Here are the questions asked.  1. In terms of its life cycle, what does the leafy bottom half represent?  2. What is the ploidy level of the portion indicated by D?  3. What type of cell is produced by the organ labeled A?  4. What cellular process produces these cells (ref. #3)?  5. What sex organ is/was located at the position indicated by B?
Their answers exposed a lot of conceptual misunderstandings when they mismatch their answers to 1-4 with ploidy level or process.  To get B correct they have to think backwards in the process to understand what took place before this stage in the life cycle.  And for those who grasp the concept, it was so easy.  The problem is that no matter how you present the material, concrete thinkers resort to memorization, even when the lab endeavors to create an investigatory approach.  When the Phactor first encountered such material as a freshman biology major, the professor, Dr. Marsh, aptly named because he studied cattails, deducted for logical inconsistencies because it was evidence you were guessing.  Even then there were howls of protest and indignation.  
Some things just don't seem to change, but Marsh is proud of me.  And the exam did one thing it was supposed to do; it discriminated among my students and will make the final grading relatively easy even if the memorizers must be cut some slack.  Sadly this was just too difficult for most of our students.  Sorry, kids; sorry, world.  You try, but sometimes you fail.  However, you may be guaranteed that those top students are quite impressive, and really understand the land plant life cycle.  
Have at it readers.