More on Plant Education - PBL and otherwise

mmphillips at mmphillips at
Mon Nov 29 08:45:26 EST 2004

Dear Plant Ed Folks,

I've gotten some good suggestions to my questions about problem based
learning and competency-based evaluation in plant biology -- some of which
were sent to you all, but others not, so below is a compilation of the
replies that came to me only.  (And many thanks to you who did reply!!)

Jon Monroe pointed toward the ASPB statement on "Principles of Plant
Biology, Concepts for Science Education" and I also found that the whole
education part of the ASPB website had some good information and links.
I'm not a member of ASPB (though I probably should be) and had not
previously explored what's available there.

My training was in ecology and I'm much more familiar with the resources
available through the Ecological Society of America.  I suggest that those
of you who have not looked at the education stuff on the ESA website do so.
(Available at:
In particular, I suggest looking at TIEE (Teaching Issues and Experiments
in Ecology)  There's a link to it from the ESA education page, but also the
direct URL is:
(Which gets you to volume 2 but you can get from there to volume 1).  There
are some good investigations.  I really like the one on environmental
correlates of stomatal density.  All the materials are in downloadable PDF

Also, the ESA has a course syllabus exchange site as part of their
education site.  I have found that very useful for teaching ecology - It
would be great to see something similar for plant bio.

I plan to use the Exotic species case study from the SUNY Buffalo site.  It
would be great if more plant cases were there.

I've put together some exercises for my class that aren't quite there yet
in terms of being designed to use the best of cooperative learning
techniques (a typical aspect of problem based learning).  But I thought I
could make them available.  Feel free to take them, make them better (and
send back the improved versions??)

>From the replies I received :

>From William Cohen:
You need to look at PBL sites at SUNY at Buffalo and at the University of
Delaware. They may not have specifics regarding Plant Biology, but there
are probably a lot of examples in the life sciences. A good personto
contact at the University of Delaware is Deborah Allen.  She is a regular
contributor to the on line Cell Biology Education

I will direct you to my colleague, Dr. Deborah Allen, in my department.
She is one of the rising stars in PBL in biology, had lots of experience
and publications in the area.  My institution maintanins a PBL
Clearinghouse to which she can refer you.  Are you a member of
ABLE,Association for Biology Laboratory Education?  If not you might find
it very rewarding. Deborah and I gave a workshop on PBL in the lab using
global warming and elevated carbon dioxide effects on photosynthesis asthe
Deborah Allen           deallen at

Bob Hodson
What knowledge, skills, and attitudes (to plants) are really essential for
students completing year 1?

Many students enter university with two important, but incorrect,
perceptions about plants that affect their willingness to be interested in
things botanical. The first is that plants and animals are essentially
different, and the second is that animals are more successful than plants,
and therefore better and more interesting i.e. plants are different and are
boring in comparison to animals. unless one is careful, such attitudes may
harden when students are forced to undertake general biology courses with a
plant component.

For me, an essential aim for a first year class is that the students with
the above attitudes to plants are disabused of them. If it requires less
jargon and fewer facts, then so be it. I am happy if students who started a
course with no great expectations come out of it with the opinion that they
have underestimated plants and that they are, at least, 'OK' . If they have
an attitude that if a 2nd year course is available they might consider
taking it, then all the better. I assume the minimum of knowledge retention
for students entering 2nd year courses - if the students come with a good
attitude, they will absorb knowledge and gain skills readily.

I therefore am of the opinion that an important aim in a 1st year general
biology course should be to demonstrate that plants and animals are pretty
similar, not basically different i.e. they are not strange, they are a lot
like us, they are good guys. Language is critical in this process - as
animals we we tend to use 'animal words' that discriminate against plants.
I feel that it helps to use 'animocentric' words to intoductory biology

For animals, we use the words taste, feel, smell, eat, see, move, speak and
pee, all words with which we are familiar. For plants, we use words such as
sense, detect, absorb, respond, trap light - all of which are very
inanimate in context, and are perceived as indicating slightly inferior
skills on the part of plants.

I taste, but a plant root detects a rich nitrogen source in the soil; I
eat, but a plant absorbs nutrients; I see, but a plant traps radiation; I
speak, but plants release and detect volatiles and respond to the signal; I
move, but a Venus fly trap reacts or a vine grows towards light; I feel
gravity, but a plant has a gravitropic response.

It is necessary to confront this animal chauvinism. A good approach it is
to ridicule it. What is the difference between the mechanisms of photon
trapping by a molecule of chlorophyll and a molecule of rhodopsin? Isn't a
receptor in the tongue basically the same as a receptor in a root? What is
the difference between a receptor in the nose and a protein that detects
methyl jasmonate? Describe the Arabidopsis expt during which a plant that
was touched at regular intervals grew taller than a plant that was not
stroked, if that is not 'feel' what is?

Animal chauvinism, a bit like consumerism, is often expressed as a view
that an organism is 'better' if it is more complex or faster. There are
many complex plant responses. For example, one can equate phloem sap to
blood. Sure the functions are not precisely the same, but phloem transports
nutrients, proteins, RNA (?), hormones and other messengers, let alone
viruses. Moreover, flow can be in two directions at once. For fast plant
responses, one can use the example of hypersensitive responses following
pathogen insult.

Often this animal chauvinism is associated with the idea that plants are
less well adapted to terrestrial environments. Both plants and animals are
of course reasonably adapted (and are continually adapting). You can
highlight the successful adaptation of plants to a terrestrial environment
by asking why we don't call a rainforest a monkeyland or a savanna, a
wildebeestland. If the whole landscape is covered by plants, they must be
doing something right! Why do we use the term 'coral reef', when it is the
lithothamnion, the algal symbionts and the turf algae that drive the

One can continue hammering the chauvinism theme by pointing out that we are
also size chauvinists, we go to zoos to look at lions and tigers and
koalas, there are no bacteria enclosures (not deliberately anyway).
Highlight our preoccupation with big organisms by asking students trivia
questions - what proportion of the cells inside their bodies are human.
Very few guess around 10%.

It is important that students are asked: if plants and animals have similar
origins (show an evolutionary tree that demonstrates (a) a common ancestor,
and (b) that the genetic distance between plants and animals is small
compared to bacterial distances), the same hereditary system (DNA,
chromosomes, genes, meiosis etc), if their biochemistry and cell biology is
pretty similar (glycolysis, L-amino acids, mitochondria, ER, Golgi bodies,
many similar enzymes), if they have lived in a terrestrial environment for
roughly the same time (plants a little longer, but still what is 50 million
years difference when one is talking about time scales of 400-500 million
years?) and have been subject to similar environmental selection pressures
(water, radiation, temp., climate changes, asteroids etc), then why aren't
they the same?

In the same vein, why are so many plant products useful as medicines? I
hold up a banana and tell the students that if 50% of their DNA is the same
as the DNA in a banana (65% for footballers) why is it so surprising that
compounds that affect plant enzymes affect animals? The plant compounds are
effectively compounds that affect similar proteins with  similar active
sites. It is surprising that we are surprised! If the world were inhabited
by triffids, they would probably use animal products as medicines. Perhaps
they might farm humans and tap their gall bladders for tonics.

That brings us to the question, if terrestrial plants and animals are so
similar, why do they look different (where are the triffids?)? One can
perform the Graham Kelly trick (GJ Kelly, patent pending!). Grab a thin
piece of meat and buzz it against the wall. It will stick and slowly fall
off. Then chuck a cucumber against a wall. As long as you are not
hyperactive, it will bounce off the wall (if it splatters you will at least
get a laugh and the students won't forget the lecture!). This can be the
intro to explaining how similar selection pressures can result in different
outcomes for a cellulose cell wall-bound, sessile, autotrophic organism
versus a cellulose cell wall-bound, sessile, autotrophic organism. It is a
basis for explaining why, despite the similarities of plants and animals,
many of the features that are peculiar to plants have appeared e.g. the
variety of plant reproductive systems, photoprotection mechanisms,
secondary metabolism. One can ask the questions, what are the alternatives
if you can't go hunting for a mate, if you can't sit in the shade when its
hot, if you can't wander across the field for a drink, if you can't run
away from a predator, or if you can't go take a leak.

One can demonstrate how well adapted plants are by showing a plant with
arrows that indicate how it senses the above-ground environment - light
intensity, light quality, daylength, gravity, temperature, wind, [CO2],
[O2], VPD, plant volatiles, herbivory - and the below-ground environment -
water, nutrients, temperature, soil texture, pathogens, [O2].

Obviously, such capabilities evolved over time as plants moved from being
terrestrial apprentices to terrestrial experts. From this base one can
introduce the plant divisions etc.

I have run out of puff!

I'm sorry that I cannot comment on ' competency based education' as I don't
really know what the term means.


Joe Holtum


 Jonathan D. Monroe, Associate Professor
 Department of Biology, MSC 7801
 James Madison University, Harrisonburg, VA 22807
 office: 540-568-6649, fax: 540-568-3333
 email: monroejd at

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