Activity help

Warwick Silvester w.silvester at WAIKATO.AC.NZ
Tue Aug 31 16:56:16 EST 1999

A quik demo of osmosis and and turgor in plants can be had if you have
giant algal cells of Chara or Nitella. Place in a large dish on the
overhead projector and exchange from water to a0.4 M sugar solution and
watch the cells go from v turgid to limp and back again. It give a vivid
demo of the power of osmosis especially when the flacid cells rehydrate.
One can also do a lot of water things on the ohead to demonstrate cohesion
and adhesion  just by moving water around on the platten and by moving a
capillary  into a drop of water and seeing the water zoom up the capillary.
It all enlarges v well on the screen and students feel v much part of the
demo. One can demonstrate change in contact angle and cohesion by adding
alcohol;  the possibilities are endless.
Warwick Silvester

>To: plant-ed at
>From: ssinger at NSF.GOV ("Singer, Susan R")
>Subject: RE: Activity help
>Date: 31 Aug 1999 13:57:57 -0700
>Sender: daemon at
>I just thought I would second the C-fern recommendation.  My intro students
>loved working with Ceratopteris last year.
>Susan Singer
>> -----Original Message-----
>> From:	spiro at [SMTP:spiro at]
>> Sent:	Tuesday, August 31, 1999 2:31 PM
>> To:	plant-ed at
>> Subject:	Re: Activity help
>> I would recommend trying c-fern for a quick demonstration.  This is the
>> fern Ceratopteris, a model system that was developed at the University of
>> Tennessee and is being marketed by Carolina for teaching grade 7 through
>> college.  Only very simple equipment and inexpensive supplies are needed
>> to
>> culture the spores of c-fern which develop into fertile  gametophytes
>> within 14 days.  In fifty minutes the students could learn about
>> alteration
>> of generations in plants, study the simple structure of these fern
>> gametophytes which develop into either male or hermaphrodite gametophytes,
>> and observe fertilization taking place.  Fertilization is triggered by
>> adding a drop of water to the ~14 day old cultures, which stimulates the
>> release of swarms of motile swimming sperm that are chemotactic towards
>> the
>> archegonia (which contains the egg) of the hermaphrodite gametophyte.
>> The
>> swimming sperm can be observed directly in the culture dish with a
>> disecting microscope. Our intro Bio students found the fertilization
>> demonstration to be really fascinating ( you have to be pleased when you
>> can get students interested in fern biology).  There is a ton of
>> additional
>> info including culture conditions, available mutants, and descriptions of
>> other demonstrations at the following web site
>> >Well, I'm one of those people that cannot say "no" and figure I need to
>> be
>> >involved in high school linkages, so I have agreed to do two 50-55 minute
>> >sessions of "non-trivial" hands on botany. The students are talented,
>> >taking  "Bio. 2", and are mostly seniors. They can take the AP exam after
>> >completing the high school course. They probably will have had no botany
>> at
>> >the time the activity takes place (early November). They are using  a
>> >college text -- Starr and Taggart.
>> >
>> >Any suggestions for a "hands-on, non-trivial" experience that we might be
>> >able to do in 50 minutes?
>> >
>> >jim
>> >*******************************************
>> >James W. Perry
>> >CEO/Campus Dean
>> >Professor - Biological Sciences
>> >University of Wisconsin-Fox Valley
>> >1478 Midway Road
>> >Menasha, Wisconsin  54952-8002
>> >920.832-2610
>> >FAX 920.832-2674
>> >jperry at
>> >
>> >*******************************************
>> Mark D. Spiro
>> Department of Biology
>> Bucknell University
>> Lewisburg, PA 17837
>> spiro at
>> phone:  (570) 577-3486
>> fax: (570) 577-3537

Warwick Silvester                      Ph. +64-7-838 4613  and voicemail
Dept of Biological Sciences          Fax +64-7-838 4324
University of Waikato                  Email w.silvester at
Hamilton, New Zealand

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