Download osmosis 10, spring 1996 - Science and Plants for Schools

OSMOSIS 10, SPRING 1996
Contents
An Introduction from the Director
Fast Tissue Culture
Kalanchoe - no classroom should be without one
Why the world needs sunshine and plants
Fast tissue culture: Teachers' Guide
Noticeboard
Letter from the Director
Dear Colleague,
We chose the ASE Annual Meeting at the University of Reading for the launch of a new SAPS
workshop on Plant Tissue Culture. Led by Mark Hanley-Browne, Mick Fuller and Fran Fuller,
this was extremely well received. Comments included: "Very good workshop"; "Well prepared
and enthusiastic presentation"; "I feel I know a lot more than I did 2.5 hours ago and that my
pupils will benefit".
A simple tissue culture protocol is included in this issue of Osmosis - more protocols to follow.
We are pleased to report a steady stream of visitors to the SAPS World Wide Web sites.
There are two sites, one on the PHYTOS server at Nottingham University, the URL is
http://nasc.nott.ac.uk:8100. The second site, which can be found on the Research Machines
Information For Learning service (the URL is http://www.rmplc.co.uk/orgs/saps/index.html),
includes a Workshop Calendar which is updated at regular intervals and articles from the
SAPS newsletters. We are also receiving e-mail from teachers and students. We hope to
build a framework in our web site for handling queries. In the meantime just keep using my email address: [email protected]
Richard Price
Director
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Noticeboard
Dear SAPS,
Growing radishes in film cans
In your SAPS Student Sheet 9, you describe a method for growing radishes in film cans. This
method involves putting a wick through the hole in the base of the film can and then resting
the can on the protruding wick, on a sheet of capillary matting. We have had several problems
with this technique. Firstly, the film cans are not very stable because they are resting on the
wick and secondly, some can dry up because the wick does not make effective contact with
the sheet of capillary matting. I have tested a new technique suggested by Mr. R. Chappell, a
science teacher at St. Bede's School. This simply involves putting one end of a long thin strip
of capillary matting through the hole in the bottom of the film can. The film can is then placed
on a cake cooling stand over the reservoir of water or nutrient solution. The free end of the
wick is passed through the mesh of the cake cooling stand and immersed in the liquid.
This solves the problems of the cans falling over or drying out: it also uses much less of the
expensive capillary matting!
Mary Northcote,
St. Bede's School, Cambridge.
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The Millennium Tree Line
Are you on, or near, the Greenwich Meridian? If so, you could take part in a project to plant a
line of trees along the meridian to celebrate the new Millennium. The idea is that this will, one
day, become a "linear nature reserve and living laboratory of ancient trees".
For further information please contact Catherine Freeman, The University of Greenwich, F
Block, Room 114, Oakfield Lane, Dartford, DA1 2SZ England. Tel 0181 331 9695.
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SAPS sponsorship
John Pattison of All Saints Catholic School, Dagenham has recently received a SAPS light
bank grant and free basic kit. He plans to use this resource with his A-level students.
However, he also has arranged a small display in the school library to stimulate interest
further down the school. One aim was to start a small club so that students can pretest their
Sc.1 investigations.
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The Living Plant Cell by Dr. Karl J. Oparka, Senior Principal Scientific Officer at the Scottish
Crop Research Institute
"...a unique teaching video designed to accompany basic plant-cell biology courses."
This is an outstanding resource for your post-16 biology courses. The video, which makes
use of state-of-the-art video microscopy, brings the structure of cells to your students in a way
no text book can. A helpful booklet is included.
Running time 26 minutes. (The UK price is £35 + VAT).
Available from:
Mylnefield Research Services Ltd,
Scottish Crop Research Institute,
Invergowrie,
Dundee DD2 5DA
Scotland.
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Kalanchoe - no classroom should be without one!
Even the name of Kalanchoe diagremontiana is impressive. This plant hails from the faraway
island of Madagascar. In the classroom it provides many opportunities for plant-based studies
at all levels. Much of the early work on the Crassulacean acid metabolism (CAM) pathway in
photosynthesis was done using this plant at the University of Newcastle which remains a
leading centre for research in this field.
The most obvious feature of this plant is the multitude of 'babies' borne on its leaves. These
are derived asexually so all are clones of the parent and are genetically identical. They are
easily removed and even start growing roots if left on the adult plant. When placed on moist
potting compost the plantlets establish themselves rapidly and can be transplanted easily
even by very young children. They respond well to varying light intensities, nutrient and
watering regimes. Crowding them in a pot creates a very clear stem elongation so the
potential for studying environmental and intraspecific effects in a genetically uniform
population is very great. Under a light bank the plants remain very squat, only elongating to
flower.
The lower epidermis of mature leaves peels off remarkably easily. Just 'crack' the leaf and
peel back! Placed on a slide and viewed down a microscope. The stomata and epidermal
cells are clearly visible. Chloroplasts can be seen in the guard cells and with sub-stage
lighting you can even tell which stomata are open. Measuring variation in stomatal densities
due to growth under different environmental conditions is an excellent exercise involving
maths and biology.
An even better subject for stomata is Setcreasea purpurea or any of the Tradescantias.
Viewing the leaf intact under the microscope reveals the giant stomata and guard cells. No
epidermal peeling is necessary. If the epidermal peel is stained with Neutral Red the
cytoplasm of the cells stains pink. Irrigating the slide with different concentrations of sodium
chloride or potassium nitrate will induce easily seen plasmolysis in the cells.
Kalanchoe flowers in the spring for me. The flowers are somewhat bell-shaped, suffused with
pink and have lovely yellow stamens. A plant about to flower will show sudden internodal
elongation - presumably a gibberellic acid effect. Maybe flowering could be induced with GA I have not tried this. The waxy flowers are about 20 mm long and borne in profusion, making
the plant an ideal subject for studying flower structure. Mature plants die after flowering. I
have never had any fertile seed from my plants. Perhaps they need an insect pollinator.
John Hartshorne,
Prudhoe High School,
Moor Road, Prudhoe,
Northumberland NE42 5LJ
England.
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Why the world needs sunshine and plants.
by Stephen Tomkins
Have you ever thought of making a model planet where the ecosystem is almost closed to
everything except light?
You can do this in a bottle.
One ecosystem that will run for months on a warm, sunny windowsill is a shrimp-world using
Artemia - the Californian brine shrimp. These little crustaceans are fun. They swim upside
down and often go about in pairs with the male mate-guarding the female. The ecosystem
runs on the energy of sunlight and the materials in the bottle which are recycled. Algae are
the key producers fixing carbon dioxide and producing oxygen. The shrimps consume
oxygen, produce carbon dioxide and eat the algae. When the shrimps die they rot and their
remains are decomposed by bacteria. The algae use the minerals released by decomposition.
This bottle planet has all the components of our world, an atmosphere, biosphere,
hydrosphere and lithosphere. On the windowsill of your classroom it's a great asset to helping
children think about ecology. What is mystifying is that the tiny algae - the plant world - are
almost invisible to children and this means that they really have to think hard about how the
shrimp world works.
A starter culture, including brine shrimp eggs and instructions, is available for £5 inclusive of
post and packing (UK only) from David Barnard, Department of Biological Sciences,
Homerton College, Cambridge, CB2 8PH England. No orders - cheques only, payable to
Homerton College.
© "Shrimp World Watchers" is a Homerton College Research Programme. 1996