What I taught today: Nuffin’!

Nothing at all! I gave the students an exam instead! While I got a plane and left ice-bound Morris to fly to Fort Lauderdale, Florida! Bwahahahahahaha!

Sometimes it is so good to be the professor. And if ever you wonder why my students hate me with a seething hot anger, it’s because I’m such an evil bastard.

Here’s what they have to answer.

Developmental Biology Exam #1

This is a take-home exam. You are free and even encouraged to discuss these questions with your fellow students, but please write your answers independently — I want to hear your voice in your essays. Also note that you are UMM students, and so I have the highest expectations for the quality of your writing, and I will be grading you on grammar and spelling and clarity of expression as well as the content of your essays and your understanding of the concepts.

Answer two of the following three questions, 500-1000 words each. Do not retype the questions into your essay; if I can’t tell which one you’re answering from the story you’re telling, you’re doing it wrong. Include a word count in the top right corner of each of the two essays, and your name in the top left corner of each page. This assignment is due in class on Monday, and there will be a penalty for late submissions.

Question 1: We’ve discussed a few significant terms so far: preformation, mosaicism, regulation, epigenesis. Explain what they mean and how they differ from each other. Can we say that any one of those terms completely explains the phenomenon of development, or is even a “best” answer? Use specific examples to support your argument.

Question 2: Tell me about the lac repressor in E. coli and Pax6 in Drosophila. One of those is called a “master gene” — what does that mean? Is that a useful concept in developmental genetics, and is there anything unique to a gene in a multicellular animal vs. a single-celled bacterium that justifies applying a special concept to one but not the other?

Question 3: Every cell in your body (with a few exceptions) carries exactly the same genetic sequence, yet those cells express very diverse phenotypes, from neurons to nephrons. The easy question: explain some general mechanisms for how development does that. The hard part: answer it as you would to a smart twelve year old, so no jargon or technical terms allowed, but you must also avoid the peril of being condescending.

Wait…I’m going to have to fly back to Morris on Sunday, and then I’m going to have to read and grade all those essays! Aargh — they’re going to get their revenge!


  1. shouldbeworking says

    I like the hard part of question 3. I just may borrow that idea for my next physics assignment.

  2. hexidecima says

    Good for you to assign them things like that. My one geology professor John Ernisee (sed and strat among other things) and who was also my advisor, did things like that. It made me a good writer which is incredibly important. He used to give us 20 essay topics and then tell us that 3 of them would be on the midterm/final.

  3. says

    My general rule of thumb is, out of three questions, one should be historical/context driven, one should be more molecular, and one shoudl be about communication/education. I don’t mind if students avoid one kind consistently as long as they can do a good job on the other two.

  4. hypatiasdaughter says

    I will be grading you on grammar and spelling and clarity of expression as well as the content of your essays and your understanding of the concepts.

    So, everything your enemies say about you is TRUE! You ARE a big meany pants!

  5. says

    That is an awesome exam. I had a western civ teacher in college who gave assignments like this, usually along the lines of “You are writing an encyclopedia entry/textbook article for Topic. With no more than two pages of text, inform your reader. Footnotes on one additional page. Assume this is for publication, so grammar and spelling count.”

  6. says

    No school today for me because of a special Lincoln’s Birthday holiday in my district. However, I gave two exams yesterday and they’re stacked up and ready to grade. Too bad, though: I’ll be out of town today and hanging out in San Francisco, so the exams have to wait. I’m sure they’ll keep.

  7. logicpriest says

    Damn I would have taken more bio classes with tests like that. I always had trouble where off days could ruin a whole semester’s GPA because I’d zone out during one of the innumerable multiple choice exams I took.

    Multiple choice.

    In college.

  8. Scientismist says

    An awesome assignment! Will you be posting, or encouraging your students to post their answers on their blogs? I still have my old copy of “The Lactose Operon” (Beckwith & Zipser, 1970). Having moved from biology to oceanography back in the ’80’s, I haven’t had an update in 30 years. Of course, the real fun for me in molecular biology was not the final story, but how we came to know what we think we know about such systems.

  9. Angela Freeman says

    Sounds much better than the exam I just wrote – an unfortunate ‘grad-level’ class where all you do is memorize structures without thinking just to regurgitate them on an exam. By far the worst way to ‘demonstrate knowledge’.

  10. Larry says

    Love the 3rd question. Its a great model to follow in posing the following question to a creobot who pulls the old 2nd law of thermodynamics out when attempting to explain why evolution is false.

    Explain the 2nd law of thermodynamics in terms a smart 12 year could understand and follow without using jargon or technical terms.

    I have always suspected that, if questioned about the meaning of this law, all one would get from the denier is a gaping mouth and stuttering.

  11. karmacat says

    I am so glad I am not in school anymore. However, I do wish medical school had been less about memorization and more about concepts and how to think through problems, diagnoses, etc

  12. says

    This reminds me of an astronomy course I took in my undergrad where Dr. Naylor always conveniently had work to do on the Keck in February.

  13. Laurence A. Moran says

    I hate to be a curmudgeon (NOT!) but I have two suggestions.

    In question #2 you shouldn’t ask about the lac repressor but, instead, ask about CRP, the activator of the lac operon. Since CRP acts on dozens of genes in the E. coli genome , it makes a much more interesting case of a possible master gene.

    Your statement in question #3 that, “Every cell in your body (with a few exceptions) carries exactly the same genetic sequence, …” conflicts with a talk I gave on Ottawa a few months ago. I believe you were there. I made fun of the IDiots for believing that to be true! Each daughter cell acquires about 0.3 new mutations every time a cell divides and recent results of sequencing different skin cells shows that they often have different copy numbers of some gene families (due to duplication and deletions). We can safely assume that no two cells in your body have EXACTLY the same genetic sequence unless they are daughter cells.

    That’s a bit more than “a few exceptions”!

    You could avoid this problem by asking how you can make a complete new frog by using the DNA from skin cells or how you can make a complete new plant by using a single cell from almost any mature plant tissue. This address totipotency without implying the all cells have the exact same DNA sequence.

  14. crocodoc says

    Hello PZ,

    As a non-biologist, I’ll need google and wikipedia to work through that exam and re-read the summaries of your lectures that you posted here. Would you mind to post examples of good answers lateron?

  15. Jim Phynn says

    I’d be interested in seeing some of the answers you get, especially to the “hard” part if question 3.

  16. New England Bob says

    PZ, you are in the neighborhood of my winter home. Is there a public event you are going to that I can attend?

  17. eric says

    After they hand them in, you should send that last question to XKCD. He did such a good job with the Up Goer Five that I bet he’d do a pretty good job at this one, even if he’s not a biologist.

  18. Caveat Imperator says

    I envy your students. My university’s Department of Molecular, Cell, and Developmental Biology rarely encouraged clear writing, and sometimes actively discouraged it.
    The question format that horrified me the most went as follows; the questions asked you name ten molecular processes, organelles, reactions, or what have you, that were involved in [system]. (would vary from course to course.) The problem was that the test design did not penalize wrong answers. So instead of fluid essays with detailed explanations that showed you understood the process well, the format encouraged memorizing everything and dumping your brain on exam day.

  19. ChasCPeterson says

    I’m going to have to read and grade all those essays! Aargh

    On the one hand, I feel yore pine. As I’ve said many times before, grading is hellish torture to me.
    On the other hand, you’ve only got ten students, right? Suck it up, man. (I gave written (half) exams to a class of 70 last semster).

    Multiple choice.

    In college.

    One can almost hear the *sniff* of contempt.
    When I’ve had classes of fewer than, say, 40 students, I prefer to give all-written exams because all considered it seems the best way to let students let me know what they know. When I’ve had classes of 100+ (and no teaching assistants with grading duties) there is no sane choice but to give all (or near all) multiple choice exams. (I write good multiple-choice questions and don’t use the crap from the publishers’s test banks, and they will make you think. My biggest class ever was an intro-bio course at a large State University with 700 students split into 2 lecture sections. (when I was an undergrad at an even larger State university, there were way too many students to do even that; I watched all the lectures via closed-circuit TV.) Hell fucking yes, multiple-choice, at serious college.)

    Here’s the thing: most of my classes have been in the 40-100 range with no help, and so for many semesters I’ve given mixed exams, different ratios but over all about half & half MC and written (no stupid matching, blank-filling or T/F, now that shit doesn’t belong in college, imo). When I’ve tracked MC and written scores separately and looked at the data (3 or 4 semesters), for a single exam I always get correlations in the .8-.9 range, and at the end of the semester over all it’s higher, .9-something. No difference in means by paired-sample tests and very few effects on course letter grades.
    moral of the story: It turns out to not matter (necessarily).
    [/ anecdote counterpoint]

  20. Genius Loci says

    Those are great, very well-written questions. My background isn’t in science, but I had no trouble envisioning how I would frame my responses to them, were I a student who had kept up with the reading and paid attention during the lectures. Then again, I used to teach writing and am a science/technical writer and editor by profession, so the thought of take-home, open-book essay exams generally don’t send me into a blind panic. And good for you for forcing them to avoid jargon. That last question would definitely be the most challenging, even for someone like me who does a lot of translation from jargon into plain English for the general public, particularly when the material is new.

    When I taught college English, what I always tried to stress (and what still seemed to evade so many students who hated writing or thought they were already God’s gift to computer science or biology and that therefore they shouldn’t have to take a college composition course) was that writing was just as much about strengthening one’s own learning and reasoning processes as it was about producing an acceptable, tangible deliverable. Perhaps even more so. You’re giving your students such a critical edge.

  21. Kevin Dugan says

    PZ, please post the results. I’ve been an IT consultant/developer for 25 years but find cellular bio and evo/devo to be so facinating, I’m contemplating going back to college.

  22. duane says

    I REALLY wish I would have had more professors like you in college. The nice thing about exams like this one is that your students, if they do it right, will internalize not only the subject material, but the ability to communicate it to non specialists.

  23. fastlane says

    Reminds me of my high school World History teacher (who was also a prof at the University of Maryland). His tests were all essay, short answer questions. He would put about 120 points of questions on the test, and we were allowed to pick which 100 pts worth we answered.

    The other option was a multiple choice test, but even if you aced those with a perfect score every time, you would only get a ‘C’ in the class. He figured if you couldn’t express your ideas in writing, that was all it was worth.

  24. theignored says

    Question 3: Every cell in your body (with a few exceptions) carries exactly the same genetic sequence, yet those cells express very diverse phenotypes, from neurons to nephrons. The easy question: explain some general mechanisms for how development does that. The hard part: answer it as you would to a smart twelve year old, so no jargon or technical terms allowed, but you must also avoid the peril of being condescending.

    The “editors” (the regulatory genes? It’s been two decades, give me a break!) decide which chapters of the same “instruction manual” are to be implemented for each cell?

  25. echidna says

    I like the idea of the third question as making it free of jargon, as if to an interested politician. However, when I explain tricky maths concepts to a smart 12 year old, I deliberately explain and use the “jargon”, because the specialised words are the “handle” that we use to encapsulate concepts. I think avoiding technical language with kids is a mistake.

  26. Genius Loci says

    True. Smart 12-year-olds love jargon. How about, “Explain it as you would to a member of your family who knows nothing about biology.”

    (I was going to suggest “your grandmother,” thinking of my own, who was very intelligent but never went beyond high school, but that would be misogynist and definitely ageist.)

  27. ChasCPeterson says

    I won’t be posting the results.

    From context, I think he probably meant to ask for the answers.