Plant Life Cycles

Ross Koning koning at ECSUC.CTSTATEU.EDU
Mon Oct 13 13:48:52 EST 1997


At 2:13 PM -0400 10/13/97, Douglas P. Jensen wrote:

>        David Kramer's post brings up one of my pet peeves in plant life
>cycles.  Text books generally discuss zygotic, sporic, and gametic
>LIFECYCLES, but they are quite confusing and often not well presented. I
>think a better way to think of these terms and present them is as types of
>MEIOSIS, each related to a specific type of life cycle.
---snip---
>        Jeez, can you tell I'm a botanist by how long I rambled on about 3
>terms?

Hi Doug!

I guess anyone can tell I'm one too!  But the value of terms
is in how they explain more than just their size might indicate...
When you have a situation that takes sentences to clarify, it is
helpful to have a one-word tool to shorten the verbage, hence the
need for the term itself.

I prefer to teach the "sporic" pattern as an archetype and let
the "gametic" and "zygotic" terms refer to shortcuts from that
archetype.  Students seem to have little problem with that
concept, and seeing human life as somehow simpler than plant
life is a fun perspective whenever possible.  Cell structure
is another place where plants are arguably MORE rather than LESS
complicated.

I'm not sure I would like these three associated with meiosis...
our students have enough trouble with meiosis in ONE form let
alone leading them to think there were three DIFFERENT kinds (they
will think mechanisms) of meiosis.  I have seen that combination
of words before in textbooks, but I think it doesn't help. In all
these life cycles meiosis takes place in a diploid cell and
produces a haploid cell via the same mechanism, so there is NO
difference in the meiosis of these cycles.  What IS different is
the fate of the products of meiosis (in gametic) or syngamy (in
zygotic). So the differences are broader than meiosis itself and
so I really prefer to associate these terms with patterns in life
cycles.

ross

_______________________________________________________________
Ross Koning                 | koning at ecsu.ctstateu.edu
Biology Department          | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA   | fax: 860-465-4479
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