Re: Pinhole Digest #472 - 09/28/00

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From: David Lauter (dyakov@ix.netcom.com)
Date: Sun Oct 01 2000 - 10:26:09 PDT

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From: "David Lauter" <dyakov@ix.netcom.com>
Subject: Re: Pinhole Digest #472 - 09/28/00
Date: Sun, 1 Oct 2000 10:26:09 -0700
Message-ID: <01c02bcc$b0a80ce0$86e76ed1@dyakov.ix.netcom.com>

Missy, I also like your question. It brings to light the sentient nature of
plants. The cell wall provides adequate support only when the energy of
water in an average plant cell is slightly lower than the energy of water in
the soil that surrounds the roots. If the energy of water in the plant is
too low the plant will wilt. Plants are very good at adjusting the energy
of their water by keeping the turgor pressure of their cells fairly
constant. We can see evidence of "turgor homeostasis" whenever a plant
recovers from a soil moisture deficit. It wilts and then springs back up.
A while back in the middle eighties I did an experiment that was very fun.
I grew cotton and peanut for about five weeks in nutrient solutions which
varied in their composition but did not vary in their osmotic pressure.
Treatments spanned a huge range of sodium/potassium concentrations. (Most
plants love to take up potassium but exclude sodium from their shoots.) Some
of the dependent variables were growth, cell turgor, cell osmotic pressure
and solute uptake. I was suprised to find that even though there were huge
differences in the solute composition of plants, cell turgor was maintained
by adjusting cell osmotic pressure to be a little higher (energy a little
lower) than the osmotic pressure of the nutrient solution. So plants can
feel the pressure inside their cells. Perhaps turgor homeostasis is simply
a function of the structure of the cell wall, which perhaps would become
leaky after a certain pressure, but as of the late eighties, I was not aware
of a mechanism for how plants feel turgor. Incidentally phloem cells have
huge internal pressures but they probably don't have turgor homeostasis.
They're glutons for photosynthate.
>Hi there -
> This is proabably a simple question that I should know the answer
>to,... but if a cell wall provides support and structure for plant cells -
>why don't animal cells need a cell wall? What does an animal cell have
that
>provides this function - or why would it not need it (in a similar way?)?
>
>Thanks!
>Missy Rock
>Madison Middle School
>Oakland, CA

Steven Eiger, Ph.D.

Department of Cell Biology and Neuroscience and the WWAMI Medical Education
Program
PO Box 173148
Montana State University - Bozeman
Bozeman, MT 59717-3148

Voice: (406) 994-5672
E-mail: eiger@montana.edu
FAX: (406) 994-7077

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Subject: RE: Global Warming = Where Goes Earth?
From: <SFPhysics@aol.com>
Date: Wed, 27 Sep 2000 13:15:34 EDT

Dear Pinhole Listers:

While I was offended by political tone of the Global Warming and NPR, PBS
posting of WinterSun, the topic of saving the planet from a scientific point
of view should be part of classes such as "Integrated Science." As a
science
teacher I try to teach open-mined inquiry and data gathering for a
step-by-step scientific approach. We should be encouraging our students to
get to the truth with verifiable facts and then postulate solutions. Taking
the political slant out of the discussion, let us look at some ideas about
global warming and our sources of energy that impact the planet:

1) We have no idea why the greatest global warming trend started some
12,000+ years ago. Certainly it was not the "oil companies" or we humans
that caused it.

2) We have had a serious increase in planetary temperatures in the last 100
years. Will this continue? So far the global warming predictions are just
extrapolations outside of our data points. We could just as well have a
return to the ice age with more sporadic interglacial periods like this one.
When the fossil fuels run out in about 100-200 years and we have not
replaced
them with any new "concentrated" energy sources, where will an overpopulated
planet find energy? Will there be another ice age as CO2 levels fall then?
We don't have all of the complex facts involving the earth's planetary
orbit,
the sun's variable output, the ocean's thermal responses, etc., to make a
cohesive workable model of the overall set of climatic systems. Let us
remember that for most of the planet's existence we did not have polar caps!
It was only when the ice ages started some 30 million years ago that the
caps
first appeared. And, all it took was Mt. Panatubo (sp?) to drop the
planetary temperature averages for a couple of years.

3) We use petroleum and fossil fuels because they have the energy
concentrated in them. To get a fractional amount of the fossil fuel energy
from solar power we would have to cover much of the deserts in the
southwestern US with solar power farms. This would severely damage many of
the ecosystems there. One of the jobs of the mirror cleaners at the Barstow
solar power plant is to gather the bird carcasses up. To go for wind power
would mean that we would have to cover the tops of mountain ranges with
turbines. Hundreds of thousands of them. The number of birds that get
killed flying into the blades would not be even a significant part of the
damage that tearing up the land to plant the solid foundations these devices
need and running power lines all over the country side would bring.

4) Fission produces by products that we as a civilization find unacceptable
because who will be here guarding the toxic milieu for hundreds of thousands
of years. We could do what the old Soviet Union did and just post signs and
abandon vast tracks of land that have become unhabitable for the next
60,000+
years. Let us face it, fission reactors just have few positives against a
plethora of negatives.

5) Fusion seems no closer than it was some 30 years ago. The new "ignition
study facility" at the Lawrence Livermore Lab has been picketed by the
misguided who think that all the larger device is for is to build better
thermonuclear bombs. Unfortunately, Congress, in their infinite stupidity,
listen to such protests and scale back on funding of what should be a truly
great, almost clean, and virtually limitless energy source. There is much
doubt that fusion power will be any further along in the next 30 years with
funding cuts continuing. There may also be the possibility that fusion is
not technologically feasible far into the future.

6) Solar cells produce huge amounts of serious pollution in their
production. We could cover most of the buildings in the country with them
but this would only provide a small percentage of the power we use. The sun
shines at an approximate "useable" power of 1mW/cm2 on a good summer day at
a
latitude of 29oNorth where San Francisco is. Your average home computer
uses
300 Watts, the TV uses 100W, the electric clothes dryer 3600W, and so on.
To
just run the TV you would need most of a roof of a residential home. This
is
because the current best solar cells are still less than 40% efficient in
their energy conversion and they must do double duty in charging batteries
for nighttime energy use. Production of batteries is another serious source
of long-term dangerous pollutants, mostly heavy metals.

7) Hydroelectric plants on rivers and streams produce thermal pollution and
change ecosystems drastically. About all of the economically useable sites
for hydro have been built on. We cannot expand on this source of energy
much
more.

8) Geothermal plants also pollute with sulfur compounds such as sulfur
dioxide that comes up with the steam. The steam also must be treated to
remove "geyser dust" witch eats turbine blades for lunch. Energy from
geothermal plants is neither cheap nor nonpolluting In tapping a steam
field
new wells must constantly be found to replace the wells that are tapped out.
All of the tailings of the drilling become toxic waste that must be disposed
of or left on site for future clean up.

9) Orbiting solar cell arrays that beam power down to earth sound
wonderful.
The only problems are that the atmosphere will warm appreciably in the
microwave beam path, airplanes could not fly through the beam without being
destroyed, birds would be cooked by the beam, putting it into orbit would
create millions of tons of pollution that would damage the ozone layer
during
launches, etc. This was truly a pie-in-the-sky scheme.

All energy production is a dirty business and saving our planet from
ourselves is a much more complex task than just blaming the oil companies,
the forrest products industry, the military, or whatever target may be your
personal bugbear. We are living in an increasingly technological society
which requires energy and energy in increasing amounts. We already have the
possibility of roaming blackouts and service interruptions as we have heard
on the news this last summer. Quite literally we have reached the end of
our
current energy production capacity. What can we do to minimize pollution
and
enlarge energy production? Our students will inherit all of the problems.
Are they aware of them? Will we have given them the analytical tools to
address the problems?

Nothing should deter the science teacher and the scientist from posing the
key questions of what we can do to slow man's negative impact on the planet.
I ask my students, "How can we live here without causing irreversible
damage?
Will we reach a point of planetary collapse where man drops back to a more
simple time after mass starvation, war, and pestilence? Will there be
another deeper "dark ages?"" All of the above are questions I have posed to
my students and the lively debates have gone on for weeks in my Lunch in the
Lab series.

Regards to all on the list and apologies for the long posting,

Al Sefl

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Subject: science fair ideas
From: "Black, Heidi" <BlackH@exchange.esuhsd.org>
Date: Wed, 27 Sep 2000 10:26:44 -0700

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Hi All,
I am looking for ideas for science fair projects-about 1000 of them! You
come up with such great ponderings, and I know we all have pet experiments
we would conduct if we had any time. If you are willing, I'd love to share
them with our kids. Most come from backgrounds of little scientific
literacy. They have the desire, but are really lost as to where to start.

Looking Forward,
Heidi Strahm Black
East Side Union High School District
Science Fair Coordinator

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Hi All,
 I am looking for ideas for science =
fair projects-about 1000 of them!  You come up with such great =
ponderings, and I know we all have pet experiments we would conduct if =
we had any time.  If you are willing, I'd love to share them with =
our kids.  Most come from backgrounds of little scientific =
literacy.  They have the desire, but are really lost as to =
where  to start.

Looking Forward,
 Heidi Strahm Black
 East Side Union High School =
District
 Science Fair =
Coordinator

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Subject: vector toy
From: "Black, Heidi" <BlackH@exchange.esuhsd.org>
Date: Wed, 27 Sep 2000 10:37:10 -0700

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AH! My vector toy source went away! I have gotten them from Laurel's
Wonders and Whimsies on Chestnut-but they are gone!!!!

Any leads? I'd desparate! I still get requests from the vector toy
snackbook activity. I have found some similar toys in a shop in Los Gatos,
but they are designed to "waddle" as they have a point that drags, and the
string attachment is too low for possibly measuring angles.

Thanks,
Heidi

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AH!  My vector toy source went =
away!  I have gotten them from Laurel's Wonders and Whimsies on =
Chestnut-but they are gone!!!!

Any leads?  I'd desparate!  =
I still get requests from the vector toy snackbook =
activity.   I have found some similar toys in a shop in Los =
Gatos, but they are designed to "waddle" as they have a point =
that drags, and the string attachment is too low for possibly measuring =
angles.

Thanks,
 Heidi

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Subject: Re: pinhole science fair ideas
From: "Paul Doherty" <pauld@exploratorium.edu>
Date: Wed, 27 Sep 2000 10:51:19 -0800

Heidi

Check out my site index where there is a list of dozens of science fair
experiments.

http://www.exo.net/~pauld/site_map.html

Paul Doherty

Paul "But it is more complicated than that!" Doherty,
Senior Staff Scientist, The Exploratorium.
pauld@exploratorium.edu, www.exo.net/~pauld

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Subject: RE: pinhole science fair ideas
From: "Black, Heidi" <BlackH@exchange.esuhsd.org>
Date: Wed, 27 Sep 2000 11:20:42 -0700

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Thanks! I've been, but I'm going back!
Heidi

-----Original Message-----
From: Paul Doherty [mailto:pauld@exploratorium.edu]
Sent: Wednesday, September 27, 2000 11:51 AM
To: Pinhole Listserv
Subject: Re: pinhole science fair ideas

Heidi

Check out my site index where there is a list of dozens of science fair
experiments.

http://www.exo.net/~pauld/site_map.html

Paul Doherty

Paul "But it is more complicated than that!" Doherty,
Senior Staff Scientist, The Exploratorium.
pauld@exploratorium.edu, www.exo.net/~pauld

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Thanks! I've been, but I'm going back!
 Heidi

-----Original Message-----
 From: Paul Doherty [<A
HREF="mailto:pauld@exploratorium.edu">mailto:pauld@exploratorium.edu</A>]</F
ONT>
 Sent: Wednesday, September 27, 2000 11:51 AM
 To: Pinhole Listserv
 Subject: Re: pinhole science fair ideas

Heidi

Check out my site index where there is a list of dozens of
science fair
 experiments.

<A HREF="http://www.exo.net/~pauld/site_map.html"
TARGET="_blank">http://www.exo.net/~pauld/site_map.html>

Paul Doherty

Paul "But it is more complicated than that!" 
Doherty,
 Senior Staff Scientist, The Exploratorium.
 pauld@exploratorium.edu,  www.exo.net/~pauld

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Subject: Re: pinhole science fair ideas
From: "Karen Kalumuck" <karenk@exploratorium.edu>
Date: Wed, 27 Sep 2000 11:51:28 -0700 (PDT)

Hi Heidi!

Get a copy of my book, Exploratorium's Human Body Explorations.....there's
28 great activities that are written in a "facilitated inquiry" style and
lots of suggestions at the end of each for extending the explorations
(perfect for science fairs). You can order them online at the
exploratorium store - click on the store icon at the bottom of the Explo
home page www.exploratorium.edu.

Have fun!

---Karen

Karen E. Kalumuck, Ph.D.
Biologist
Exploratorium Teacher Institute
3601 Lyon St.
San Francisco, CA 94123
415-561-0313
karenk@exploratorium.edu

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Subject: Re: pinhole mac fries
From: <NFetter@aol.com>
Date: Thu, 28 Sep 2000 01:21:34 EDT

Mr. B,
the "natural" ingredients are most likely potatos, salt,and veggie
oil--that's french fries.
Neil Fetter

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