To the Fun Science Gallery Contents

 

SCIENCE EXPERIMENTS ON
ENVIRONMENTAL EDUCATION AND BIOLOGY

Giorgio Carboni, March 2001
Translation edited by Michael Easterbrook

 


CONTENTS

Presentation
Soil composition
Soil moisture and permeability
Soil erosion
Soil profile
Hydroponic systems
Aquaria and terrariums
Building a Pond
Biospheres and ecospheres
Garden in a bottle
Recycling
Composting
Volcano
Recognition of smells
Collection of animal tracks
Seeds germination
Soil ecosystem
Raising animals and plants
Culture of protists
Raising pond organisms in aquarium
Breeding amphibians in aquarium
Culture of vinegar flies
Breeding earthworms
Culture of butterflies
Regeneration of animals
Production of oxygen by photosynthesis
Respiration in plants and animals
Alcoholic Fermentation
Lung model
Extraction of the chlorophyll
Paper chromatography
Paper electrophoresis
Plant tissue culture
Culture of luminescent bacteria
Drawing nighttime insects
Cellular division
Model of mitosis
Spontaneous Generation
Experiments with protists
Internet resources
Conclusion
Bibliography


PRESENTATION

Some readers wrote to us asking for more experiments and toys to build. As we need of some months to complete an article, we thought of collecting interesting topics, equip them with a short description and links to already existing sites. In this way, our readers may quickly find more instructive and, above all, amusing activities. The experiments which we have gathered in this article concern mainly the environment and the biology. As times go by, many of the links we have proposed will die, in return new sites will be born. We cannot continually update this page. In order to allow to our readers to compensate, we are providing at the end of most experiments, keywords which can be used with search engines, in order to find other sites for themselves. Don't use all these keywords together, but use them according the combinations which seem suitable to you. When searching the Internet, it is easy to find too many documents and ones that are not appropriate. We recommend adding a term such as: school, students, experiment, test, classroom, homemade, building, making, homework, science fair, science project, lesson, lesson plan, hobby.

WARNING: Some of these experiments can be dangerous. When children are doing them, an adult must always be present to avoid any damage or harm. In any case, we do not assume any liability. As for the safety and the liabilities, we recommend you to read our Warning page.

Have a good time!

Experiment of soil composition

ANALYSIS OF THE SOIL COMPOSITION

The soil is composed of many different sized particles. With this simple experiment you can separate the main components of the soil and evaluate their proportions.
1 - Go into a field an collect a sample of soil. Put it in a jar of water. Stir it well and let it settle. Observe and describe the different layers of materials.
2 - In water, particles settle more quickly the bigger they are. It is possible to use this property to determine the amount of each component of the soil. Put 3 parts water and 1 part of soil in the container (try 1 cup soil and three cups of water in a quart jar); shake the container for 5 minutes and let the material set. With reference to the figure 1, after 40 seconds measure the thickness of sediment. Call this A; after 30 minutes measure again and call this B; after 24 hours measure C. Now, by subtraction, you can determine the thickness of the main layers: C-B = layer of clay, B-A = layer of silt, A = layer of gravel and sand. Using a sieve with 2 mm holes (less than 1/8 inches), you can separate the gravel from the sand and determine their ratio. On the basis of these data, calculate the content (%) of each component of the soil sample.
3 - Repeat the same experiment with soil collected in other places or that have a different geological origin (i.e: meadow, wood, river bank) or anyplace the soil has a different consistency or texture (i.e: muddy, sandy). Describe the composition of each soil and try to explain the differences. You can also apply this technique to evaluate the composition of the soil for a potted plant, and correct it. Example: if water doesn't drain well, would more sand help? If it needs to hold water longer would clay or organic matter be helpful?
4 - With a microscope, measure the size of the particles. With a clock, measure the time to drop to the bottom of a jar of water.  time of the particles in water as a verses their size. Then graph with the Y-axis for the size of the particle and X-axis the time to fall.
http://interactive.usask.ca/skinteractive/modules/agriculture/activities/soil.html   Soil and Environment Activities
http://fbe.uwe.ac.uk/public/geocal/soilmech/classification/soilclas.htm   Soil description and classification
Internet keywords: soil sedimentation test.

 

SOIL MOISTURE AND PERMEABILITY

The composition of the soil has important consequences on its permeability towards water and on its ability of keeping it. In a flower pot does it retain water or does it drain well. With this experiments you will be able to evaluate the characteristics of some basic components of soil.
1 - Put sand in one glass, clay in another, and mixed soil rich in humus in a third. Push a finger into each glass and smear the sample to the wall of the glass. Pour some water in each glass and observe what it happens: in the glass with sand the water falls to the bottom quickly, in the one with clay water remains in the top or falls very slowly, in the one with mixed soil and humus water is absorbed and distributed in a homogenous manner (figure 2). Try to give an explanation of these different properties. What consequences can a storm have on lands with these different compositions?
2 - Assess the drainage and water holding ability of different soils and make a connection with their composition determined from the previous experiment.
In this test we have not taken into account the important role of the organic substances provided by the humus.
http://ag.arizona.edu/turf/tips1095.html   Soil Characteristics and How They Affect Soil Moisture
http://wcuvax1.wcu.edu/~burr/soilinfo.html   Soil permeability
Internet keywords: soil permeability moisture.

Soil permeability



Experiment on the erosionEROSION OF THE SOIL
This experiment is as simple as it sounds.
1 – Take some soil, make a little mountain at least 20 cm high, with steep walls and a flat top. With a hose, water it down, avoiding direct jets (figure 3). You will see the borders slide down and the heap of mound of soil progressively take the typical profile of a true mountain. Observe and describe what happens during this artificial rain.
2 - Redo the test. This time insert an impermeable clay layer on top of the mountain and then some regular soil: the lake of water on the clay layer should give rise to a sudden landslide of liquid mud.
3 - Build another mountain with stones, clay, sand and ground in different positions. Observe the different behavior of the materials towards the artificial rain.
4 - Sow grass on a new "mountain" and pour water on it after the grass has grown.
http://www.kenyon.edu/projects/farmschool/nature/eropro.htm   Erosion Project
http://spider.silsoe.cranfield.ac.uk/iwe/erosion/   Erosion and sedimentation
Internet keywords: soil erosion

 

SOIL PROFILE

The ground is modified and enriched by the plants growing on it. Making a section of soil (figure 4), you can observe different layers: a layer rich in organic matter, the humus (O); a layer rich in roots and living organisms (A); a layer less rich in life, but still used by roots (B) and an inert soil (C).
1 - With a shovel, dig a hole of at least 40 cm (15inches) deep in a meadow. Describe the layers of soil which you see, perhaps take some pictures.
2 - Do the same in other kinds of soil, for example in a wood, or near a river. Make comparisons and try to explain the differences you observe.
It is easier to do these excavations when the ground is moist, rather than dry or muddy.
http://www2.nrcs.usda.gov/teachers/soil_profil.htm   An Illustration of a Soil Profile
http://library.thinkquest.org/J003195F/newpage5.htm   Soil profile
Internet keywords: soil profile.

Soil profile

 

Hydroponic system HYDROPONIC SYSTEMS

Hydroponics is a method of growing plants without soil. Plants are simply placed in water with the necessary chemicals. As plants are deprived of support from the ground, they will fall down. To support the plants, an inert material like expanded clay pebbles is used in a pot in the tank (figure 5). Before inserting a plant in a hydroponic system, you must carefully remove all soil from the roots otherwise bacteria will putrefy them.
For many houseplants you can use tap water. Though, particularly for vegetables, it is advised to add appropriate nutrients. This cultivation method has the advantages of both requiring less frequent waterings and using very little water. With this system you can grow nearly any houseplant or vegetable. Hydroponics is useful also to show what nutrition plants need.
1 - Place some houseplants in hydroponics.
2 - Try hydroponics with vegetables and find the suitable nutrients.
http://www.cpes.uoguelph.ca/STAO/hydrop.html   Hydroponics in the Classroom
http://weboflife.arc.nasa.gov/stellar/Activities/hydro/Hydroponics.html   Hydroponics Module
http://www.hydrogarden.com/class1/curriculum.html   Bradley Hydroponics
http://www.education.eth.net/experiments/framepages/ccorner_funtime29.htm   Growing plants without soil
http://www.classroom.net/edsoasis/Treasure/pbradley.html   To teach orphaned children how to grow their own food with hydroponics (gardening that uses very little water).
http://www.attra.org/attra-pub/ghveg.html   Organic Greenhouse Vegetable Production
Internet keywords: hydroponics classroom.


BUILDING AQUARIA AND TERRARIUMStapes on the aquarium plates

Making an aquarium or a terrarium is not a complicated thing. Learning to build them is very useful for those who are fond of breeding animals, observing them, taking pictures and movies. You can use an aquarium to breed fish, amphibians, protists, algae, artemia, shrimps, etc. You can use a terrarium to breed many species of animals, but avoid raising species which suffer in captivity. Aquaria and terrariums can be used also to take pictures of animals temporarily taken from their environment.
In their simpler form, acquaria and terrariums are simple glass boxes enclosed on 5 sides and which can be provided with a lid. This simple container is suitable to breed amphibians and as a terrarium. Aquaria for fish require a compartment for a filter, a pump for water circulation, another pump for air, a thermostat, lighting, etc. We'll deal of the simplest aquaria.
How you can build an aquarium? In first you have to make a drawing. The bottom glass has to be surrounded by the other four walls and it has to be the thickest. The thickness of the plates has to be proportioned to the size of the aquarium. Avoid building too wide, and more importantly, too high an aquarium. The pressure of the water increases and could unglue the plates. After having drawn the acquarium you have to cut the glass plates by means of a glasscutter. To do this keep the glasscutter vertical and push down with force while you move it along a ruler. This operation require practice, so use some scrap pieces until you have the necessary manual ability. It is important you use a sharp glasscutter, kept in oil to avoid rust. Before gluing the slabs, you have to round off the edges with sandpaper in order to remove their sharp edges. With some acetone, clean the slabs where the silicone rubber will be deposited. As the acetone is toxic, work outdoor or in a well ventilate piece. Use high quality transparent silicone. To keep the internal walls free of excessive glue, on the slabs and near the gluing positions, place stripes of sticking tape (figure 6). When the silicone is cured, remove these stripes and the excess glue.
LOOK OUT!: handling and cutting glass is a dangerous operation which has to be made only by adult people wearing gloves and a heavy apron. A way to elegantly solve this problem is to order plates. A hardware or building supply store can help. Never move aquaria and terrariums containing water or stones, move them only when they are empty. Do not place aquaria in positions where a water leak could damage something below them, for example over electrical devices or sockets, and books. Only adults should handle glass-made aquaria or terrariums. Give children transparent plastic tanks. Do not keep dangerous or rare organisms. Do not breed and most important, do not free species which do not belong to your environment! Do not free sick animals or plants.
http://www.thekrib.com/TankHardware/   Building Tanks
http://www.hobbyschool.com/reef/Shopping/diy.htm   Reef Aquarium Guide
http://www.multimania.com/cybaqua/plau/tout.shtml   CyberAqua (list of links)
Internet keywords: aquarium glass homemade.


BUILDING A POND

Ponds are among the richest and the most interesting natural environments to observe. To make a pond it is sufficient to have a garden or, a meadow or a wood near your home. It is not necessary to be large, a square meter (9 square feet) of surface is sufficient, but two(18 sq. ft.) are better. Find a shady position in the garden. Dig a hole of about 2 square meters, 50 cm(2 feet) deep. At least one side, the border has to gently slope down to allow to little animals to enter and leave, for hedgehogs and opossums to drink and to birds to bath without being too deep. Put some sand in the bottom. Leave the grass on the side. Bare roots are okay. Waterproof the hole with a tarpaulin of white PVC. Why white? Because you can see aquatic animals better when they come near the shore. Cover the border of the tarpaulin with the grass sod. Allow the tarpaulin to extend for at least 40 cm (16 inches) beyond the sloping shore. In this position you can keep the water in such a way to create the typical conditions of a marsh. Fill up the pond with tap water and shovel some sand or soil in the bottom: they will benefit the aquatic plants. Go to a natural pond or marsh and collect some aquatic plants. If it is possible, carry some gallons of water from the pond and pour them into your puddle, which will be enriched with microorganisms, algae, and animals, which live in ponds. In few days, your little pond will become green with algae and very rich of protozoa. Rapidly dragonflies will come to lay eggs, boatflies, coleoptera and aquatic spiders also will come. In the spring, frogs and newts will come to lay eggs. The observation of the life in a pond is fascinating. You can remain for hours watching the organisms, which live in this ecosystem. Buy books to recognize the organisms that live in the ponds. See bibliography (5, 6). These texts will also give you also useful information on the habits of these plants and animals. For an exercise, note your observations in a book, glue pictures, and sketch drawings. Every year, during the fall, you should clear out the pond. Shovel out the stinking mud, wash the tarpaulin, or changed it if it leaks, put some tap water, winter rain will supply the remaining part. In spite of what shopkeepers will tell you, your pond does not need pumps to circulate water, nor aerators, nor falls, nor fountains, nor anything else. The pond is better to be as natural as possible. Little ponds of private gardens are very important to amphibians. Avoid introducing fish. They will eat the eggs of the amphibians and the tadpoles. Moreover, the newts will keep the pond free from the mosquito larvae. When there are tadpoles, your pond will be visited by water snakes, with difficulty you will notice of them!... and --- don't be frightened: they are harmless!
http://members.aol.com/marylady/pondpals/resource.htm   Pond Links
http://www.citlink.net/~missy/pondlinks.htm   Pond Links
http://www.angelfire.com/ri/skibizniz/microhab.html   Multiple Microhabitat Pond Microcosm  (good cross section of a pond)
http://pionet.net/~kuseld/pond.htm   A Large Pond
http://home.flash.net/~blhill/pages.aux/pond/construction.html   Pond Construction
http://www.exit109.com/~gosta/pond.sht   Building a Pond
http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/pond.html   "Pond" Cultures of Microscopic Invertebrates
Internet keywords: pond building homemade.


EcosphereBIOSPHERES AND ECOSPHERES
Normally, the term of biosphere means the part of our planet that hosts life. Instead, the term ecosphere means the all of ecosystems. Lately, these terms are used also to mean the closed, artificial ecosystems. They exist as different kinds of ecosystems like these and with different size, for example a quite large one has been built in order to study the ecological equilibrium of the Earth and to check the possibility of building permanent, autonomous bases in the future on the Moon, Mars, in space. There are other smaller artificial closed ecosystems, like the ones contained in a glass sphere and marketed under the improper name of biospheres or ecospheres.
Plants consume carbon dioxide and produce oxygen; on the contrary animals consume oxygen and produce carbon dioxide. Plants produce organic substances, which are eaten by animals; in turn animals produce organic fertilizers for plants. What is the general balance of all those exchanges? What happens in a small sealed, ecosystem? Our planet is a closed ecosystem. It may not seem small, anyway it is essentially closed. Earth does not exchange important amounts of anything with space. As time goes by, billions of years, slowly our planet has acquired an accumulation of oxygen with enough concentration to support animals. Today, given that it oxides rocks oxide exposed by erosion and animals that breath, this gas is in equilibrium. The same is true for small, closed ecosystem. This cycle of oxygen can stay in equilibrium for a long time, even many years, keeping both the plants and animals alive. The important thing is to obtain an equilibrium among the mineral substances, the plants, and the animals which compose them. Then here with a glass sphere like the one for red fish (figure 7), you can make a "world in a bottle"! To make your own, you can also use a colorless glass demijohn. Put in it a little soil and/or sand, some stones, some protozoa, algae, aquatic plants, some animals like waters snails or tiny crustaceans like water fleas, little shrimp, and fill with water leaving some air. Then seal the container. Put this little world in the light, but without direct sunlight. Keep a record of how the system evolves. Observing how life continues for years inside this limited space is fascinating and educational. In fact, these closed ecosystems are a model of the Earth. Now, imagine that a particularly active shrimp eats all the algae of its biosphere? What would happen? Probably, the oxygen would be subtracted by many processes, and since there is no more algae to produce more, the shrimp would die, suffocated. The fragility of these little ecosystems makes us understand how fragile our ecosystem is... but it doesn't seem to worry many people.
http://lifesci3.arc.nasa.gov/SpaceSettlement/teacher/lessons/bryan/ecosys/  Closed Ecosystems
http://www.angelfire.com/ri/skibizniz/  Microcosm (theory)
http://www.geocities.com/RainForest/3918/mce.html  Research on Materially Closed Ecosystems
http://www.eco-sphere.com/  Ecosphere Associates, Inc.
Internet keywords: closed ecosystems microcosm.


GARDEN IN A BOTTLE
The bottle garden is a close relative of the biosphere: a tiny garden growing inside a bottle, a glass sphere, or a demijohn. The main difference is that soil is the main component not water. The container can be kept sealed or opened like a terrarium. Ours will be more for just plants whereas the terrarium may have animals. These gardens in a bottle, can be cured and perfected as a system, they are also very decorative, in fact you can treat them as a bonsai with not only a single tree, but whole landscapes. A carefully chosen stone becomes a rock, a small plot of moss represents a great prairie. A contorted, little plant is now a hundred year old tree. Maybe a marsh wetlands with peat moss, mushrooms and ferns is more to your liking. Maybe appropriate succulent plants with sand and rocks for a vast desert landscape. The choice is yours. There is no rigid rule about being either an open or a closed garden. It maybe useful to keep the lid on to retain water. Or eventually, the plants grow up and need to hang down the outside.
If the container is always sealed, the challenge becomes quite demanding. In fact, it then is necessary to obtain an equilibrium between plants and animals in order to keep an effective cycle of substances and energy, but if this is difficult in a predominantly water environment, it is even more difficult in a just moist environment. So, the garden has to contain a moist soil, plants, little animals like terrestrial isopods (i.e.: sow bug, pill bug), earthworms, etc. Plants have to be resistant to high moisture and have a small size and limited growth. To avoid roots rotten, you can also try to refer to hydroponics and substitute the ground with small sized expanded clay or with gravel. In this case you will have more difficulties in hosting animal species, so it will have to be left open. It is important you place your garden in a cool and well illuminated place, but away from direct sunlight. Open or closed, a bottle garden is a fascinating thing, and the idea itself of a little and self-sufficient world is fascinating as well. There are people so fond of bottle gardens they work at them a long time, taking care of them using long and thin tools and to observe these environments till they imagine to be one of their inhabitants.
Then choose among these main options:
1 - Opened bottle garden, containing moist ground, plants and possible little animals. It is suited for people who love taking care of gardens and who have a flair for
the architecture of little wide spaces.
2 - Opened bottle garden, prepared in hydroponics and containing plants. It is suited for those who tend to forget to water their plants.
3 - Sealed bottle garden, holding moist soil, plants, and some little animals. This exercise is suitable for people who are keen on biology and scientific research. They will have to find appropriate plants and animals suitable for a sealed ecosystem and will have to achieve the necessary conditions for a long survival. This research, bibliographic in part and experimental, will keep students happily busy for long time.
The educational value of these little ecosystems is evident. They can be carried out even in a school, where the teacher will be allowed to illustrate their characteristics to pupils and encourage interesting discussions. In the web sites below, you will find important practical information in building your bottle gardens.
http://www.ville.montreal.qc.ca/jardin/en/info_verte/feuillet_terrarium/feuillet_terrarium.htm   Terrariums : Miniature Worlds in a Bottle!
http://www.bbc.co.uk/gardening/howto/backtobasics/bottle_garden/index.shtml   BBC online, how to gardening, bottle garden
http://forums.gardenweb.com/forums/load/contain/msg071125216319.html   Forum
http://www.feminin.ch/jardinage/Bouteille.htm   Un jardin en bouteille
http://www.ville.montreal.qc.ca/jardin/info_verte/feuillet_terrarium/feuillet_terrarium.htm   Le terrarium : Un monde miniature dans une bouteille!
Internet keywords: garden bottle jar, jardin bouteille bonbonne.


RECYCLING
Industrial societies manufacture huge quantities of goods. Once used, these products are cast away. Hence, on one hand we substract great amounts of resources from nature, on the other hand we make enormous heaps of garbage which pollute the environment. If you think of it, a lot of materials which are discarded could be reused. In fact, metals, plastic and glass can be used in manufacturing new items. Paper and fabric can be turned back into pulp and fibers, and reassembled into new products. Organic wastes of kitchen, usually made of vegetable and animal substances, and garden material, can be composted and used as fertilizer. Wood can be burned, yielding electrical energy, heat and carbon dioxide which will be used by other plants to produce more wood. Recycling of waste materials has the double advantage of reducing the need for raw materials, and the amount of rubbish.
Every day for a month, separate the different kinds of scrap of your home, weight them and write out a list. At the end, estimate the amount of materials which can be recycled, evaluate the recycling and waste management program of your community. Highlight the problem areas of the system. Assess the problems created by not easily recyclable things, and by the polluting ones: paint cans, batteries, oils, detergents, medicines, etc. Bring out the difficulties and the questions facing particular problems in the recovery of wastes. Ask the authorities of your city. Write a guide for families on how treat wastes in the right manner. Show this guide and the report of your research to your teacher.
http://www.edf.org/issues/Recycling.html   Environmental Defense, Recycling
http://www.deq.state.la.us/assistance/recycling/index_school.htm   Recycling - At School
http://www.obviously.com/recycle/guides/hard.html   Recycling Obscure Materials
http://grn.com/grn/  Global Recycling Network
http://www.obviously.com/recycle/   The Internet Consumer Recycling Guide
http://www.plasticbag.com/  Plastic Bag
http://www.recycle.net/recycle/sites/index.html   Recycler's World
Internet keywords: recycling.


COMPOSTING
In nature, the remains of dead organisms, that is vegetable and animal tissues, become the food of other organisms like little mammalians, insects, protists, plants, mushrooms, and bacteria. For billions of years nature recycled biological substances instead of letting them accumulate in useless heaps and this has helped to maintain our planet, keeping it clean and hospitable for the innumerable generations of species which have lived on it until now. While primitive men and countrymen recycled their organic scraps, until not long ago in the modern cities these wastes have been carried to large dumps where they pollute the environment and water tables. If you have a garden, you can perform a simple and educational experiment, which will allow you to recycle your organic wastes.
Build a container large enough to hold the organic wastes of your garden and kitchen. Some old lumber will do. Leave a space of about a centimeter (half an inch) between the boards for air circulation. Throw your organic waste in the box, eg: grass cuttings, fallen leaves, and the remainders of the kitchen. Avoid meat. Cover all with a shovel full of soil, and water them. Many organisms will rally to feast and decompose these substances. Among them there will be earthworms and mostly bacteria. Their work is such that some heat will be generated. At the subsequent Spring, empty the container. You can use the compost you have obtained by spreading it on the kitchen garden and in the garden. You can also use in flowerpots, just sift out the large parts first. Examine which organisms, besides the bacteria, live in the composter. You will find earthworms, terrestrial isopods, millipedes, etc. Describe the ecosystem of the composter.
http://www.vegweb.com/composting/   Composting Guide
http://www.mjjsales.com/articles/how-to-compost.html   Basic information about home composting
Internet keywords: compost composting.

 

VOLCANO

Collect some small wooden sticks and some dry paper. Make a cone of about 30 cm (one foot) tall with the sticks and paper. Put humid sand and soil around the cone to make up a little mountain. Now, dig a tunnel in the base of the mountain until you reach the sticks. Light the paper and you will see the volcano to give out smoke and some flame (figure 8). You can find other volcano models in the following site:
http://volcano.und.nodak.edu/vwdocs/volc_models/models.html
Internet keywords: volcano model.

Volcano model

RECOGNITION OF SMELLS
Who said that man does not have a good sense of smell? When people go hunting, men of certain tribes use the sense of smell to pursue the prey. Why us, men and women who live in cities, do not use the sense of smell any more? Probably this is due to the fact we are so surrounded by stinking gas, such as car exhaust, that often we would rather hold our breath than be sensitive to smells. In a city it is so difficult to feel like smelling that we have practically lost the use of our sense of smell. This is a true pity, because the sense of smell is a very ancient sense which directly communicates with the memory without passing trough the linguistic areas (which cleverly mistakes everything). A scent recall memories like nothing else can do. The sense of smell could also allow us to recognize the food which is served us and to evaluate its quality. Have you ever noticed that a cat, even if it stands at the foot of the table, knows very well what we are eating, even without seeing it? The sense of smell would allow us to recognize people, but isn't done for this... yet dogs and cats recognize us mainly from our scent. Our skin smells, it has a personal smell which often we kill under a layer of perfume. Yet our bodies, the body of males and females, communicate each other even by means of natural scents. Pheromones are suspected to spark off the so-called "love at first sight". Smells are able to get us such beneficial sensations that they are at the basis of the aromatherapy, a method for recovering the psychological equilibrium. Hence, it should be important to recover this forgotten faculty. You can start this recovering by means of some simple experiments which can be done even in a nursery school:
1 - Collect a series of natural perfumed objects, such as: rosemary, celery, onion, carrot, garlic, ground coffee, chocolate, lemon, orange, tangerine, lemon verbena,
mint, thyme, sage, cinnamon, nutmeg, clove, violet, carnation, rose, cut grass. Put each of them in a little jar. Call one child at a time and blindfold them. Now, ask them to recognize a scent, one at a time. Fill in a form and give a prize to the three best "noses".
2 - Another exercise consist of sniffing one another with opened eyes and then, after being blindfolded, try to recognize the friends by the sense of smell.
These simple experiments are able to activate and keep alive the sense of smell of a child perhaps for all his life.
Internet Keyword: smell aromatherapy student.


COLLECTION OF ANIMAL TRACKS

After a shower, the soil is soft and the animals which walked there, leave tracks. By means of plaster, you can obtain the mould of these tracks and make an
interesting collection (figure 9). The experiment is very simple: it is a question of bringing a little plaster in dry form, some water, a bowl to mix the plaster,
and a spoon to stir. But, to which animal belong the tracks you have picked up? From here start the research of information. They exist books which give the picture of the tracks of many animals. Moreover, recognizing the animal which left the track is not sufficient: it is necessary to know something of its behavior, etc. From the simple collection of tracks you will be curious to know the animals of your land. Our article: "Environmental Exploration and Protection" provides you some indication on this topic. This experiment will open your eyes so you can observe the territory around you when you walk in natural environments with more attention. Plaster can be used also to obtain the mould of fruits, barks and other natural objects. From the cast you can also obtain the original shape.

http://www.freeweb.pdq.net/headstrong/track.htm   Casting animal tracks
http://www.gov.ns.ca/natr/wildlife/conserva/03-03-5.htm   Collecting Animal Tracks
http://140.211.62.101/lessons/collecting/animaltracks.html   Animal Tracks
http://eduscapes.com/42explore/animaltracks.htm   Animal Tracks (links and pictures)
Ricerche in Internet: animal tracks plaster cast.

Cast of a track
Figure 9 - Taking a mold of a track. (Courtesy of:
http://www.freeweb.pdq.net/headstrong/track.htm)

SEEDS GERMINATION
In its simpler form, this experiment is particularly suited to elementary schools.
1 - Put some beans in a little jar containing some moist cotton wool. Keep the jar closed to maintain the humidity. Every day pull out the cotton and observe the state of the seeds and measure the length of their roots.
2 - Students in junior high schools or high schools can try to evaluate the influence of parameters such as temperature, light and nutrients on the speed of germination of the seeds. If seeds are placed in gelatin, it is possible to observe the germination without extracting them from the jar.
3 - You can also collect seeds of different plants and determine their vitality (percent of seeds which germinate) as a function of time to harvest.
http://kabt.org/Labs/Seeds.htm  Exploring Seed Germination
http://www.rohmhaas.com/company/plabs.dir/htmldocs/germinateseeds.html  Germinating Seeds on Gelatin
http://www.sci.mus.mn.us/sln/tf/books/great.html  The Great Seed Mystery For Kids
http://versicolores.ca/seedsoflife/ehome.html  The Wonderful World of Seeds
Internet keywords: germination seeds student.


SOIL ECOSYSTEM
An ecosystem consists of the whole community of living organisms (biocenosis), the abiotic component of a certain environment (biotope) and their relationships.
The relationships essentially consist in a flux of substances which pass from the non-living components to living ones and in a flux of energy which passes from the photosynthetic organisms (plants) to the herbivorous animals, then to carnivores. The wastes and the dead organisms are then decomposed by the micro-organisms which brake down the substances back to simple components, in a full cycle.
1 - With a shovel in a field or in a wood, dig a square hole of about half a meter (1 1/2 feet) square and about 40 cm (18") deep. Describe the non-living components of the soil and all forms of life you find: roots, earthworms, snails, centipedes, spiders, crickets, etc. To complete the description of the ecosystem of the soil, look for information on the role of each of these organisms and the relationships with the other forms of life of this environment.
2 - In similar way you have studied the soil ecosystem, you can analyze other ecosystems such as the ones in a forest, pond, shore, or desert.
G. and L. Durrell (2) can be useful, or there are many other books on this matter.
http://www2.nrcs.usda.gov/teachers/soil_ecosystem.htm   An Illustration of a Soil Ecosystem
http://www.cciw.ca/eman-temp/reports/publications/sage/sage9.htm  Protocols for a Soil Ecosystem Approach for Characterizing Soil Biodiversity
Internet keywords: soil ecosystem.


RAISING PLANTS AND ANIMALS
(General instructions for the different animals will be described later.)
Breeding living being is a fascinating and educational activity. The organisms you can raise are numerous: harmless bacteria, yeast, protozoans, rotifers, fresh water sponges, hydra, planaria, vinegar eelworms, earthworms, enchytraeus, tubifex, chironomids, nematodes, little fresh water shellfishes (daphnia, cyclops, etc), artemia, isopods, centipedes, millipedes, snails of water and earth, bivalves, bugs (drosophila, flies, moths, tenebrio, crickets, praying mantis, etc), aquatic bugs (boatfly, whirligig, larvae of dragonfly, nymphs of aquatic bugs as those that are found under the stones of a river), colonies of ants, prawns, fishes, amphibians, reptiles, birds, small mammals. Besides, you can raise microscopic and unicellular algae, fresh or salt water algae, aquatic plants, terrestrial plants of all types (grass, flowering plants, succulent plants, orchids, carnivorous plants), mold, mushrooms, lichens, musks, ferns, etc.
To raise these with success you have to reproduce the best possible conditions of the natural environment where the organism usually lives, to feed it in a suitable manner, and to keep away their natural enemies. The texts listed at the end will supply you with the necessary information for the preparation of media for the microorganisms, the culture medium for the plants, the food for the animals you will breed.
We want to advise you against raising exotic species which inevitably contaminate the local environment. In fact, after the first enthusiasm of ownership, people often get tired of taking care of it and after a while they want to get rid of it. Since they do not want kill it, they free it outside. In this way they cause big problems to the natural ecosystem. If you want to get rid of a being which does not belong to your environment, deliver it to an environmental organization. Breeding local species is much less harmful. Also you should avoid raising wild and complex animals for a long time because they suffer living in a limited space: they are born to be free with lots of room. You should keep an animal in a terrarium only for the time to observe it and take some pictures. Smaller, simpler creatures like insects and mollusks have fewer problems. Moreover you must avoid breeding rare, endangered, or threatened species. Finally, avoid introducing sick animals or diseased plants into the environment.
http://www.flinnsci.com/homepage/bio/livemat.html   Live Material Care and Feeding
http://www.ee.pdx.edu/~davidr/discus/livefoods/cultures.html   Food and Medicine - Live Cultures
Bibliography: 1 cap 9: Maintaining Organisms for Laboratory and Classroom Activities. 3 Classroom Creature Culture: Algae to Anoles.


BREEDING OF PROTISTS
Whoever has seen these organisms knows how charming they are. Click on the image to your left to observe a short movie of a ciliate. Click a second time to stop it. If you own a compound microscope you will find it very useful to have a little pond, an aquarium or at least a glass to raise a rich community of protists. You can also try to breed just a single species.
1 - Generic breeding: after a while, a colony of algae and protozoa or many other species will form in any pool of water. So, to obtain a rich culture of microorganism, you can fill a transparent container with tap water and place it outside, but avoid direct sunlight. To speed the emergence of the protists and to supply them food, add a little dry grass and leaves. For a container, you can use a simple glass jar, a plastic basin, or an aquarium.
2 - Selective breeding: if you are fond of protists you may find it very interesting to selectively raise them. You will need a container for every species. Place a suitable culture medium in each container. Normally, a culture medium means some water with appropriate micronutrients needed by the protists. A simple medium for general use in growing microscopic algae is made of tap water with a handful of soil boiled for some minutes. Let this solution cool and settle for a day, this also allows oxygen and carbon dioxide to reenter the solution, then filter it. You can find recipes for more special media in texts devoted to raising protists or at websites of companies which sell the microorganisms. Some are listed at the end. So put the newly separated individuals in a jar. The jar will have to contain a suitable culture medium and will have to be closed in such a way to allow air to enter, but not dust, which could carry spores of other protists and bacteria. Normally a larger lid then necessary, which just sits on the top or a film of cellophane with some pinholes will work.
How do you obtain the species to be raised? One method is to buy them commercially. Be sure to buy a harmless species.
Another solution is to isolate the species from the natural environment. Collect a sample of water, possibly with algae or soil from an interesting puddle of water. Place this material in a petri dish. Use a stereoscopic microscope and a thin pipette to collect the protists which interests you and place them in a jar. If you want to select the individuals of a single species, temporarily put the protists of one species into their own petri dish until you have collected all of them and placed them with their fellow species. Then you can transfer the colony to a more permanent home. Bear in mind that some bacteria are necessary because they produce some vitamins the protists aren't able to make, also bacteria are the food for many of the protozoa.
3 - An interesting research project is to adjust the culture medium for a given species. Try to make changes in the composition of the colony. To do this, prepare many test tubes with the same medium and with about the same density of protists. After having modified the composition of the medium in different ways for each test tube, you can evaluate the effect of each change by counting the number of individuals in a drop of culture, every day. Clearly the positive changes will give make more crowded cultures.
Especially if you raise algae, measure the value of the pH in your cultures. If necessary, neutralize the solution with baking soda or with vinegar, depending if the pH is acidic or base.
LOOK OUT!: In these experiments, need the help of a biologist to avoid culturing dangerous microorganisms. Even with help, keep the cultures only for a short time, wash your hands, wash and disinfect all tools which have been in contact with the cultures.
http://www.bio.utexas.edu/research/utex/   UTEX, The Culture Collection of Algae. Information on algae and culture mediums (choose: "Media recipes").
http://www.BSSPweb.freeserve.co.uk/bsspsite2/frames.htm   Culture Collection of Algae and Protozoa
http://megasun.bch.umontreal.ca/protists/pcco.html   Protist Culture Collections  (list of sites. You can find the composition of mediums of culture also)
http://www.science-projects.com/safemicrobes.htm   Micro-Organisms for Education
http://www.life.umd.edu/classroom/bsci485/lab.html   Laboratory Methods
Internet keywords: protists algae culture media medium.


RAISING POND ORGANISMS IN AQUARIUMShrimp
As we have said, ponds are one of the richer and more interesting natural environments to observe. Anyway, it is not always easy to follow the movements of its inhabitants because often they head for the bottom or in another hidden place. The reflection of the sky on the water surface and the presence of floating algae make them harder to see. It is possible to solve most of these problems by creating a pond in an aquarium. It is a question of simply putting water in an aquarium, collected from a natural pond and adding some animals and plants collected in the same environment like: water snails, little fresh water shellfishes, boatflies, whirligigs, larvae of dragonfly, nymphs of aquatic bugs, prawns, etc. Every week, you have to scrape off the algae from the inside walls of the aquarium so you can see into it. You have to exchange a third of water with tap water. It is best to let the tap water sit for a day before using. The observation of the life inside this little pond will be simply fantastic. You will see the animals and the plants in an easy, well lit, and at close range. This view is nice enough for pictures and movies. Try to describe the behavior of the animals living in your aquarium, the interactions among them and with the environment where they live. Add pictures and drawings to your work.
http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/pond.html   "Pond" Cultures of Microscopic Invertebrates
http://www.cis.yale.edu/ynhti/curriculum/units/1992/5/92.05.07.x.html   Pond Ecology
http://library.kcc.hawaii.edu/CTSA/publications/Artemia.htm   Hatching of Artemia


Triturus vulgarisBREEDING AMPHIBIANS IN AQUARIUM

Breeding amphibians is very educational because it allows people to follow the development of the animals from a egg to the metamorphosis. Collect some frog, toad or newt eggs from a pond. Put them in an aquarium with water collected from the same pond or tap water that has stood a week. This period of rest is necessary to allow chlorine to dissipate and to allow the water to enrich with microorganisms, which will be food for the tadpoles. Observe and describe the development of the embryo and then that of the tadpole. Describe the shape of every species, noting distinguishing characteristics and marks. These will be helpful in identifying them. In the beginning, these animals feed on microorganisms in the water. When their legs appear, and perhaps a few days before, it is necessary to give them some boiled and minced spinach or better some boiled and squashed string beans. A snail or an earthworm cut into pieces will supply useful proteins to them. The larvae of newt are carnivorous and feed on water shellfish and mosquito larvae. After their metamorphosis they are happy to find small worms and pieces of earthworms, but this is also the time to free them. Take them back where you gathered the eggs. It is possible also to raise adults in a terrarium, but we advise you this is a difficult and demanding enterprise given the necessity of breeding flies other creatures to feed them.
http://www.girosi.com/reptiliaamphibia/siteframe.htm   Reptilia & Amphibia
http://www.wnrmag.com/stories/1996/apr96/frog.htm   All About Amphibians
Internet keywords: raising breeding amphibians aquarium.


Culture of drosophilaCULTURE OF VINEGAR FLIES
Drosophila, best known as vinegar fly or fruit fly, is the little fly you see flying around vinegar and on fruit during the fall. Why raise vinegar flies? To observe their development, to observe the chromosomes of their salivary glands during division, to perform experiments on genetics, finally as food for amphibians that have just completed their metamorphosis. In this case it is necessary to breed a species that can't fly. You can obtain individuals with vestigial wings (wings which are not fully developed) at a university Biology or natural sciences department.
Culture medium recipe for drosophila: water 83 ml, agar-agar 0.8 g, sugar 5 g, brewer's yeast 10 g, alcohol 1.3 ml, nipagin
0.25 g. Nipagin M is used as a preservative in foods and cosmetics, like agar-agar, you can buy it at the stores that sell science items for laboratories. Mix the yeast and the sugar, add agar-agar and water and simmer for 3 minutes. Turn off the heat. Dissolve the nipagin in alcohol and add to the rest when it has stopped smoking. Mix and let it set.
You can find other recipes at the following websites:
http://ceolas.org/fly/intro.html  A quick and simple introduction to Drosophila melanogaster
http://www.intellweb.com/gcka/flies1.htm   Fruit Flies - Drosophila melanogaster
http://www.thebomb.clara.co.uk/drosophila.html   Drosophila Culture (how to culture flightless fruit flies)
http://www.accessexcellence.com/AE/AEPC/WWC/1994/observing.html   Observing the Development of Drosophila in Apple Juice Agar
http://www.accessexcellence.com/atg/released/0083-BettyAnnWonderly/lab1.html   Drosophila Genetics Lab I
http://www.ifas.ufl.edu/~entweb/amer_bio.htm   A bibliography for an insect field biology course
http://www.ac-toulouse.fr/svt/droselev.html   La drosophile (in French)
Internet keywords: drosophila culture -cells, wingless fruit flies vinegar fly.


BREEDING EARTHWORMS
Raising earthworms is an interesting activity for children in elementary and junior high school. For people who own amphibians, it is an important source of food. Making such a farm is very easy. You have to simply make a heap of soil and mix some cut grass and other kitchen vegetable scraps and fruit. This culture does not need special care, except for keeping it humid, watering at least every two days in summer. Once in a while, add other vegetable waste and every two weeks mix the heap with a shovel. You can observe earthworms' digestive and circulatory systems by dissecting them.
Internet Keyword: earthworm breeding vermiculture.

Cage for caterpillars and butterflies

CULTURE OF BUTTERFLIES

The beauty of butterflies makes their culture particularly charming. Do not believe you will immediately have these beautiful insects, in fact for most of the time you will have to raise caterpillars and preserve pupae. Only at the end will you have butterflies. To culture these pretty insects, you first have to read texts about lepidoptera and practice in the field. In this way you will learn how to find butterfly eggs, to raise caterpillars and to keep pupae, waiting for the butterfly to emerge. Usually, butterflies prefer one or a few kinds of plants called hostplants. Caterpillars feed only on these plants and it is only on these that the adult female lays her eggs. So, in order to find the eggs of a given species of butterfly it is necessary to know which are its hostplants and when they lay eggs.
You should breed caterpillars in well ventilated cages. They have to be closed with mosquito net to avoid predators (figure 14). In fact, many bugs lay their eggs in the body of caterpillars. You have to feed your caterpillars with fresh leafy branches of the host plant. To do this you can pot these plants and insert them in the cage, or you can insert the cage over a branch without cutting it from the plant. If this is not possible, cover a branch of the plant with a cloth bag including the caterpillars. Cure the pupae according the suggestions in the books. When butterflies emerge from their cocoon, free them where you have collected the eggs. If you want to keep some adults to admire them, put them in cages like the one of the figure 14 and nourish them with mixtures of water and honey. Often, the caterpillars you find in nature are victim of bugs which lay their eggs on the caterpillar. In this case, there are little dark spots on the caterpillar skin. You can raise these caterpillars to study their parasites.
http://www.conservation.state.mo.us/nathis/insects/butterf/   Butterfly Gardening and Conservation
http://www.csiro.au/helix/rbw/richmond.htm   The Richmond Birdwing Butterfly Conservation Project
http://www.nhm.ac.uk/entomology/hostplants/   Caterpillar Hostplants Database
http://butterflybreeders.com/pages/positionpaper.htm   Unsure About Butterfly Releases?
Internet keywords: butterfly breeding culture.


REGENERATION OF ANIMALS
Some animal can be cut in half and from each part will grow a complete individual. Try to cut in half a planaria, a hydra, a tubifex. Keep these "pieces" in their natural environment and you will see they will regenerate the other part.


PRODUCTION OF OXYGEN BY THE PHOTOSYNTHESISPlants produce oxygen
Photosynthesis occurs in the chloroplasts of the vegetable cellules. In this process carbon dioxide and water are combined to produce sugar and starch. In order to allow this synthesis, some energy from the sun is needed. Plants use these substances also to make proteins. In this way, plants are able to produce the substances they need, whereas animals, to obtain them, have to feed on plants or on other animals. As "waste" or byproduct of photosynthetic process there is oxygen: 6CO2 + 6H2O + energy = C6H12O6 + 6O2.
In order to show the production of oxygen during photosynthesis, you can use a water plant. As shown in figure 15, immerse the plant in a tankard of water, cover the plant with a transparent funnel and put a test tube on the funnel. Make sure at the beginning there are no air bubbles in the tube. Expose the plant to sunlight and after some time you will see bubbles of oxygen gather on the test tube then collect to form a larger bubble.
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookPS.html   Photosynthesis ***
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookTOC.html   Online Biology Book


RESPIRATION IN PLANTS AND ANIMALS

Photosynthesis and respiration

Volumeter

In some way, respiration can be considered the opposite of the photosynthesis: the organism demolishes sugars to obtain the energy necessary for its biochemical processes (figure 16). Hence, the energy organisms use is supplied by the Sun in the form of light during photosynthesis. The process of oxidization of glucose happens through many stages and can be summarized in the following reaction: C6H12O6 + 6O2 = 6CO2 + 6H2O + energy. The final stages occurs in the mitochondria as energy, carbon dioxide, and water are produced. How can you see carbon dioxide, coming from the mitochondria? When breathing, plants and animals emit carbon dioxide and water vapor.
1 - The presence of carbon dioxide in the breath of animals can be shown by having a boy or girl blow into a solution of lime water Ca(OH)2. In presence of carbon dioxide lime water becomes milky. Buy the lime in a hardware or paint store.
2 - As shown by the figure 17, place a little animal inside a plugged flask. As time passes, part of the oxygen will be consumed by the respiration process, and the same number of molecules of CO2 will be produced. In this way, there will not be any change in the volume of the gas contained in the flask. To show the consumption of oxygen, it is necessary to subtract the carbon dioxide. To do this, you can use a piece of paper soaked in a solution of 10% of potassium hydroxide (KOH). In order to increase the surface of the sheet, fold it. Instead of this sheet you can use a tube test stuffed with cotton wool soaked with the same solution.
To highlight the reduction of volume of the gas inside the flask, insert a pipette with a capillary tube on the end through the plug of the container. Add a drop of colored water with a trace amount of detergent. The movement of this drop, in reference to a ruler, will give you information on how much oxygen is consumed. The second tube which crosses the plug will be useful to you to set the stained drop, but during the experiment it has to be closed.
Pay attention to not suffocate the animals. You can also make this experiment with protists, yeast, and bacteria. In the case you will want to study the respiration of plants or algae, you will have to keep the flask in the dark to prevent photosynthesis. With these tests you can measure the consumption of oxygen in the living organisms. As the temperature also affects the volume of the gas, in these tests it is important you keep the temperature constant. Pay attention when handle the potassium hydroxide because it is caustic. Safer to buy the solution already made than mix it yourself. Avoid touching it with bare hands and particularly protect your eyes. Do not allow any animals you use for the tests to be come in contact with it either. When using this substance, children must be supervised by an adult.
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookGlyc.html   Cellular Metabolism and Fermentation
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookTOC.html   Online Biology Book
Internet keywords: respiration mitochondria experiment.


ALCOHOLIC FERMENTATIONAlcoholic fermentation
Fermentation is a "respiration" which does not use oxygen and which for this reason is called anaerobic. In these experiments we will point out the production of carbon dioxide during fermentation.
The oxidization of glucose in living organisms occurs in two principal phases: the glycolysis and the respiration.
Glycolysis happens in the cytoplasm of cells, respiration inside the mitochondria. The yeast cells can grow both with and without oxygen, but in the absence of oxygen, the yeast cells limit themselves to use glycolysis. In this case, they demolish the molecule of glucose into molecules of pyruvic acid which then they convert into acetaldehyde and lastly into ethyl alcohol or ethanol. During these reactions, the yeast cells obtain energy for their metabolism, without using proper respiration. As we have said, a final product of this reaction is ethyl alcohol. For this reason, this process is often called alcoholic fermentation. During fermentation of the must, the yeast cells yield from 12 to 17% alcohol. Besides the energy, the other important product of this fermentative process is carbon dioxide. In fact wine is often rich in this gas and is then called sparkling. Now let us pass to the experimental part.
1 - Introduce some brewer's yeast (Saccharomyces cerevisiae) mixed with water and sugar in a flask. Close the container with a rubber balloon. As time passes, you will see the balloon inflate, showing the production of carbon dioxide.
2 - If you want to get quantitative measures, which will allow you to evaluate the effect of parameters such as the temperature, the substrate composition, etc. Close the bottle with a rubber plug and pass a pipette with a capillary end through it, See figure 18. Place a drop of colored water inside the capillary. Now, knowing the internal diameter of the capillary, the shifting of the drop along the tube in a given period of time, will give you the amount of CO2 produced.
3 - Make other tests replacing the sugar with cabbage cut into thin pieces and boiled, potatoes, apples, crushed grapes, vegetables, etc. Often, these products are rich in starch, a compound similar to sugar and which is used the same as sugar by the yeast. Evaluate the different productivity in carbon dioxide by the different substrata. It is indicative of how much sugar and starch are in these substances.
4 - How to distinguish carbon dioxide from oxygen. Are both gases being produced in the different processes of fermentation, respiration and photosynthesis? If you succeed in collecting sufficient amounts of these two gases, you can make them bubble in a solution of lime water: while the carbon dioxide makes this solution cloudy by forming calcium carbonate, the oxygen does not.
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookGlyc.html   Cellular Metabolism and Fermentation ***
http://www.accessexcellence.com/LC/SS/ferm_index.html   Microbial Fermentations: Changing The Course Of Human History (Information)
Internet keywords: yeast fermentation alcohol.

 

Lungs model LUNG MODEL

Contrary to what people think, lungs do not have muscles of their own, but they are dilated or compressed by means of the movements of chest and diaphragm. The device of figure 19 shows how a diaphragm causes air to enter and leave the lungs. In the phase A, the balloons have to be as empty as possible. If you are a teacher, ask to your pupils what would happen if there was a hole in the bottle. Then make a hole, so everybody will see that, even if the diaphragm is lowered, the lungs will not fill with air. Yet it is easy to close the hole and restore the functioning of the lungs. To prove this, seal the hole of the bottle with some sticking tape and move the diaphragm again. This simple experiment shows how a hole in the chest could be fatal. Also how you could save a person by simply plugging the hole. If you have difficulties in finding the Y tube to build the model of the lungs, just use a tube. You will only have one lung, but the principle is the same and you know that in reality there are two.
http://student.biology.arizona.edu/sciconn/respiratory/lung.html  Do-It-Yourself Lung Model


EXTRACTION OF THE CHLOROPHYLL
The chlorophyll in plants can be used for a chromatography experiment where you separate the different pigments, and test their fluorescence. In the chloroplasts there are many photosynthetic pigments: chlorophyll a, b, c, d, phycocyanine, phycoerythrin, carotene, xantophills. Their type and amount depends on the plant. Some of these pigments are soluble in water, others are insoluble. It is possible to extract the former ones using water as solvent, it is possible to extract the second ones using alcohol or better yet, acetone. Pay attention because both alcohol and acetone are flammable. As acetone is also toxic, use it only out of doors or under a fume hood. We will also try to extract the pigments of yellow or red leaves.
Preparation of vegetable tissue: Collect some green leaves from a plant. Insert them in a blender with some water. Blend them until you obtain a dense and homogeneous cream. You can proceed with this for the water part of the experiment, otherwise, spread the cream on a clean ceramic or plastic surface and allow it to dry. In this way, you will obtain a powder you can use with different solvents. Take a little of it and put it in a mortar with some solvent. Refine the mixture with the pestle. If you are using acetone or other toxic solvents, work outside or under a fume hood.
Do NOT insert solvents in the blender, other than water. They could emit dangerous and toxic vapors and could catch fire from the sparks of the electric motor. Also, the solvents could attack the plastic material of the blender (especially acetone), causing small leaks ruining the container. An adult must be present when these experiments are made.
1 - Extraction of the pigments with water: crush the vegetable mixture in a mortar adding a few drops of water to obtain a creamy product. Then add a little more water (the liquid needs to be as concentrated as possible) and filter the mixture. Collect the liquid.
2 - Extraction of the pigments with alcohol: do as above, replacing the water with 95% alcohol. To enhance the extraction, pour the alcoholic puree into a test tube and this in a bain-marie or in a pot or in a beaker containing water. Boil until alcohol will become green. During this operation, if necessary add alcohol to the mixture to replace what has evaporated. Use electric stoves or a hot plate, do not use a gas flame or gas stove. Filter the mixture and collect the liquid.
3 - Extraction of the pigments with acetone: adding a little acetone, (not too much since the liquid has to be as concentrate as possible.) crush the dry leaf powder in a mortar. Filter the mixture and collect the liquid. You can also allow some of the solvent to evaporate later.
4 - Make the same extraction using yellow leaves and then using red leaves. These are collected in the Fall after they turn color.
5 - In a dark room, try to illuminate each of these extracts with UV light. They should fluoresce. Compare the fluorescent emission of the different extracts.
6 - Try boiling the vegetable material before blending it. Check to see if you got the same results that you had with fresh material.
7 - Repeat the procedure and save the liquid for the next procedure: "Paper chromatography", make a chromatography test of the different extracts of green, yellow and red leaves. Compare the chromatograms among them. Try to identify the pigments. Test the fluorescent emission from them.
http://alamo.bu.edu/labs/Chloro3_1.html  Extraction of Chlorophyll and its Fluorescence
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookPS.html   Photosynthesis ***
http://www.furman.edu/~lthompso/bgy34/sunshade.html  Light Dependence of Photosynthesis in Sun and Shade Plants
http://www.people.fas.harvard.edu/~dlrobert/Pigments.html  Algal Pigments (method of extraction and Rf of photosynthetic pigments of algae)
Internet keywords: chlorophyll extraction leaf mortar


PAPER CHROMATOGRAPHYPaper chromatography
Chromatography is a method of separation of substances based on their different mobility in a given stationary support. If you have a mixture of substances, chromatography can allow you to separate them. For example, inks are usually formed by a mixture of dyes, with the chromatography you can separate them and then analyze and identify them. Chromatography is also used to obtain large quantities of a pure substance. There are many methods of chromatography. Among them there is paper chromatography, the thin layer chromatography (TLC), gas chromatography, the liquid phase chromatography, the column chromatography. Usually the mixture of substances to be separated is inserted in a solvent. The type of solvent and of stationary medium can be chosen in a wide range of possibilities. Usually, this choice is made according to the molecules to be separated. According to the situation, one can exploit the molecules different size, chemical affinity toward the support, the amount of ionization, pH, solubility in water, etc. This experiment is for home or school so we use solvents and supports that are easy to find. Test tubes are often used to contain the solvent vapors, keeping the paper from drying and not overexposing the experimenter. Later on we will give you some experiments for paper and thin layer chromatography.
Also calculate the value of Rf of each band isolated (with reference to the pencil line, Rf = distance moved by the solute / distance moved by the solvent).
In these tests, the mixture to be examined has to be in high concentration. You can prepare the mixture according to the preceding experiment. Cut a paper filter stripe narrow enough so that it can be inserted in a test tube without touching the walls (wider at the bottom), as shown in the figure 20. With a pencil trace a horizontal line at 25 mm, (1 inch) from the bottom of the stripe. Place a little drop of mixture on this line and let it dry. Place another drop on the previous drop and let it dry. Repeat this operation to obtain a small, very concentrated spot. With a pin, fix the stripe to the bottom of the tube plug. Pour several cc of solvent in a test tube. There needs to be enough so the solvent is about half way between the bottom of the paper and the 25mm (1 inch) mark on the paper.
Insert the stripe in the tube. The smaller part of the stripe has to plunge into the solvent without touching the bottom of the tube. The pencil line and the spot have to be at about one cm above the surface of the solvent. For capillary action, the solvent will be absorbed by the fibers of the paper and, when it reaches the spot, it will start to carry the substances present in the mixture. According to their characteristics, these substances will travel faster or slower among the fibers of cellulose and the faster one will pull a head of the slower and show as separate bands on the paper. Remove the stripe before the solvent reaches the end.
With a pencil, immediately mark the position attained by the solvent and let the stripe dry. Here a list of the first test you can do:
1 - Mixture = black ink, solvent = water, support = filter paper. It is best if the paper is of pure cellulose, anyway you can try other types of paper as well.
2 - As mixture use different inks, tomato juice, carrot juice, red turnip juice, red cabbage juice, leave extract, etc.
3 - Use first alcohol and then acetone as solvent. Pay attention because these solvents are flammable, and acetone is also toxic, so do this experiment outdoors or in a fume hood. The solvent has to be able to dissolve the components of the mixture. For example, water is not suitable for fat substances, use acetone instead. People use many substances as a solvent. You will find some of them listed in the sites listed below. As we said in the previous experiment, the various mixtures have to be prepared in water, then dried and dissolved into a little solvent. The mixture needs to be as concentrated as possible.
4 - Use plates for thin layer chromatography as support. Buy them in stores which sells chemical laboratory items. Often, these stores are located near universities.
5 - Make other tests using plates for TLC you have made by yourself. To this scope try alumina powder, calcium carbonate, silica gel, magnesium silicates, etc. To compact the support material from a powder, use a binding agent such as soluble starch, plaster, gelatin, Arabic gum, etc. As a support or base use glass, aluminum, or plastic plates. You can use also acetate sheets like those used for transparencies.
http://www.ctl.sri.com/pals/tasks/5-8/PaperChrom/  Paper Chromatography
http://www.accessexcellence.com/LC/SS/chromatography_background.html  An Introduction to Chromatography ***
http://library.thinkquest.org/19037/paper_chromatography.html  Paper Chromatography
http://155.135.31.26/oliver/satcoll/papchrom.htm  Paper Chromatography
http://www.iit.edu/~smile/ch9413.html  Paper Chromatography
http://ekcs.neric.org/~jbuckley/lelab/chromatography.html   Paper Chromatography on Chlorophyll
http://matrix.mvhs.fuhsd.org/~i-heng/Biowebsite/journals/vol1/1/a2.html  Paper chromatography applied to spinach chlorophyll
http://www.doggedresearch.com/chromo/experiments.htm  Paper and Thin Layer Chromatography Experiments
http://home.earthlink.net/~dayvdanls/photolab/photolab7.htm   Paper Chromatography Rf Calculations
Internet keywords: paper chromatography rf school.


PAPER ELECTROPHORESISPaper electrophoresis
Electrophoresis is another separation technique. It is based on the different mobility of ions (molecules which are charged) in a support which is subjected to an electric field. Ions run more or less quickly along the substrate according their charge, size, shape, etc. According to the technique which is used, the apparatus consists of two small basins which contain an electrolyte, a support (i.e.: filter paper, cellulose acetate strips, polyacrylamide gel, or a capillary tube), an electrical DC power supply and two electrodes. Electrophoresis is widely used to separate substances such as amino acids, proteins, strands of DNA, etc. As in the case of chromatography, people use different supports and solvents according to the substances to be separated and the techniques used. C. L. Stong, on the magazine "Scientific American" proposed an experiment on paper electrophoresis (4).
1 - As shown by the figure 21, inspired by this article, place two little basins a few cm (one inch) apart. Pour in the basins an electrolyte made of a teaspoon of table salt and another of baking soda in 300 ml(1 1/2 cups) of tap water. Place a glass plate on the two basins and on it place a stripe of filter paper soaked with the electrolyte. This stripe has to be immersed with each end in the electrolyte in the basin for to complete the electrical circuit. With a pencil, draw a line across the filter paper and place a little drop of blood on it. Cover the paper with a second glass plate. Put an electrode into the electrolyte of each basin and apply 45V in direct current (from 4 to 8 Volt per cm). You can obtain this from 5, 9volt batteries connected in series. With the passing of time, you should see 5 little spots move toward the negative electrode. These spots are made of different proteic components of the plasma: globulins (alpha, beta, gamma), albumin and fibrinogen. In reality, to make these substances better visible it is necessary use a stain such as bromphenol blue. Lacking it, try red cabbage juice.
2 - Try also to separate the components of the substances already used in the chromatography experiments and observe what it happens. Keep in mind that some of these substances may not be ionic.
LOOK OUT!: Do not use high voltages for this experiment. Never touch the electrodes, the electrolytes, or the paper stripe. Take care never to short out the two electrodes. Finally, we recommend to insert a fuse on one of the two cables. The fuse will break the circuit when there is too high a current. We suggest about 10 mA. At the end of the migration of the spots, remove the electrodes from the basins and take off the cables from the batteries.
http://www.chemistry.adelaide.edu.au/external/Soc-Rel/Content/electrop.htm   Electrophoresis (an introduction)
http://www.chemistry.adelaide.edu.au/external/Soc-Rel/Content/cap-el.htm   Capillary Electrophoresis (CE)
http://a32.lehman.cuny.edu/molbio_course/agarose.htm   Agarose gel electrophoresis for DNA
http://a32.lehman.cuny.edu/molbio_course/overview.htm   Molecular Biology Course Overview
http://faculty.uca.edu/marc.hirrel/bio1/GelElectro2.htm   Protein Gel Electrophoresis
Internet keywords: electrophoresis introduction.
Bibliography: 1 p184. 1 p 207. 4.


PLANT TISSUE CULTURE
If placed in a suitable nutrient environment, cells and tissues of many organisms are able to reproduce and form new plants or animals. Now, we will deal with vegetable tissues, whose culture is simpler than that of animal cellules and tissues. It is necessary to prepare a nutritive and sterilized culture medium for the piece of plant tissue. Keep the culture in the suitable conditions of light and temperature and which vary from plant to plant. Over many days, you will observe the growth of a callus or roots or shoots. In this way you can obtain even whole plants (cloning). These experiments show that special cells keep all the information necessary to generate the whole plant.
As we have mentioned, it is necessary avoid bacteria and moulds in the cultures. For this you will need sterilize tools, vials, tubes, and nutrient medium. Place each in an autoclave for a ten minutes or, lacking an autoclave, a pressure cooker. The tissues as well have to be free from microorganisms and they have to be sterilized with bleach (40% solution for 15 min) or with alcohol.
The transfer of the tissues into the test tubes has to be made in aseptic conditions, using a sterile box. Lacking that, make your first trials in a quiet place, as devoid of wind and dust as possible. The culture medium should contain water, vitamins (particularly those of the B-complex. For this, use yeast extract), sugars, mineral salts. To enrich the water with mineral salts, boil some water with a handful of soil, then let settle and filter it. Usually, people also insert 0.5-0.8% of agar-agar to "solidify" the medium. As culture medium, coconut milk has been used. It contains mineral salts, sugars, vitamins and growth hormones.
1 - For yours first tests of micropropagation, use strawberries tissues.
2 - If this simple experiment interests you, you can continue on the way of the in vitro culture of vegetable tissues. In fact you can propagate a lot of plants in this way. Plants easy to culture are the following: tomato, potato, strawberry, chrysanthemum, geranium, sunflower, tobacco, carrot and onion. You can use tissues obtained from seeds, such as the embryo, but you can use also tissues taken from adult plants, such as tissues of roots, stems, apical buds, shoots, leaves, even single cells. Each plant and tissue has its own needs. They are different from each other. You can try the influence of the vegetable hormones, special nutrients, etc.
This field is very broad and complex so, if you are interested in continuing with these experiments, you can buy special books and you should build a sterile box.
http://tomgreen-ext.tamu.edu/mg/tissue.htm  Plant Tissue Culture for the Gardener
http://user.school.net.th/~anuparp/bptc1.htm  Basic Principle in Plant Tissue Culture Technique
http://www.flytrap.demon.co.uk/cc/data/tcn1_man.htm   Plant Tissue Culture Kit Manual
http://www.biotech.iastate.edu/publications/lab_protocols/AV_Micropropagation.html  Plant Micropropagation Using African Violet Leaves
http://aggie-horticulture.tamu.edu/tisscult/microprop/microprop.html  Plant Tissue Culture (links)
Internet keywords: in vitro culture plant tissue micropropagation.


CULTURE OF LUMINESCENT BACTERIA
A lot of organisms emit light. Of course you know fireflies, but there are also other luminescent organisms such as some fishes, mushrooms, bacteria, dinoflagellates, and shellfishes. The culture of luminescent bacteria is not difficult. What you have to do is to get a strain of luminescent and harmless bacteria and raise it in a suitable culture medium. A bacterium widely cultured and used also for lessons in schools is the Photobacterium phosphoreum, now renamed: Vibrio phosphoreum.
Search for information about the mechanism of the bioluminescence. You can find information for this culture and general information on the Internet at sites listed later. There is a lot of information on bioluminescence on the Internet. There are even amateur sites devoted to this topic. You can buy the Vibrio phosphoreum at commercially, such as the ATCC (American Type Culture Collection) http://www.atcc.org/. You can find other firms of this type on the Internet, using the keywords: culture collection. Also try the links for the protists experiment. These companies also supply the culture media and in their sites you can often read their composition.
LOOK OUT!: In these experiments, need the help of a biologist to avoid culturing dangerous microorganisms. Even with help, keep the cultures only for a short time, wash your hands, wash and disinfect all tools which have been in contact with the cultures.
http://www.didier-pol.net/4BAC-LUM.html  Utilisation Pedagogique de Bacteries Luminescentes (in French)
http://www.farmacja.amg.gda.pl/~microbio/bakterie_sw/index_en.html  Luminescent Bacteria
http://www.unibo.it/isbc/Files/BC_PlanktonNekton.htm  Bioluminescence in Plankton and Nekton (there is a list of luminescent organisms)
http://www.ncbe.rdg.ac.uk/ncbe/PROTOCOLS/PRACBK/flash.html  Flash! Bacterial illumination
http://www.disknet.com/indiana_biolab/b203.htm  Isolation of Pure Cultures Of Bacteria (Please, read the safety warnings present in this website)
http://siobiolum.ucsd.edu/biolum_web.html  Bioluminescence Web sites
Internet Keyword: luminous bacteria luminescent bioluminescence luciferin luciferase.
To find companies which sell strains of microorganisms use the keywords: culture collection.


DRAWING NIGHTTIME INSECTS
Are the insects which fly around lamps at night attracted by light or heat? To find out, use a clothing iron and an electric lamp. The electric lamp produces light with a little heat, the iron produces only heat. Put both on a table. Keep them at least a meter (about a yard) apart and with the emitting surfaces turned away from you. Note the different behavior of insects. Mask the lamp with plastic sheets of different colors and verify if bugs are more attracted to a particular color. This is also a method to capture nighttime insects, particularly moths, so you can observe them with a lens or a stereoscopic microscope.

 

CELLULAR DIVISION

The fast growing roots of plants have cells which actively divide. Observe with a compound microscope the apex of an onion, garlic, or bean root. You can observe cells and their chromosomes in various stages of the cellular division, or mitosis.

1 - To carry out this experiment, immerse the lower part of an onion in water and leave it to root for four or five days. When the roots have grown by a couple of centimetres, cut off some of the ends of 1-2 mm in length. Place them on a microscope slide, cutting them according to length. Add a few drops of muriatic acid (check that it is a 10% solution of hydrochloric acid) and keep the root tips immersed in the acid for approximately 15 minutes. The root tips should be flaccid, if not, prolong their exposure to the acid. Rinse away the acid with distilled water (or tap water). With 2 long pins, separate the fragments as much as possible so that they are very thin. Colour them with 0.5% Toluidine blue. After 2 minutes, cover with a coverslip, crush the tips and wash away the dye by adding water on one side and absorbing it on the other using a paper towel. With a microscope, search for cells undergoing mitosis. For further information: http://www.funsci.com/fun3_en/mitosis/garlic.htm

2 - In the cells of the salivary glands from the larva of Drosophila (vinegar or fruit fly) you can observe the cellular division.

http://saps1.plantsci.cam.ac.uk/worksheets/ssheet17.html   Mitosis in root tips ***
http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html   Online Onion Root Tips. Determining time spent in different phases of the cell cycle
http://www.biology.arizona.edu/cell_bio/cell_bio.html   Problem Sets & Tutorials
http://138.192.68.68/bio/Courses/114/roottip.html   Preparing Onion Root Tip Squashes for Mitotic Chromosomes
http://www.udel.edu/hodson/207/labmanual/lab9.html   Mitosis and Chromosomes (onion and drosophila)
http://www.furman.edu/~worthen/BGY30/s2000/Divlab.htm   Mitosis, Meiosis, Chromosomes and Karyotypes
http://www.jccc.net/~pdecell/celldivision/oniontip.html   Mitosis in Onion Root Tips.
http://www.pgjr.alpine.k12.ut.us/science/whitaker/Cell_growth_division/mitosis.html   Mitosis
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookmito.html   Mitosis ***
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookTOC.html   Online Biology Book
Internet keywords: onion root tips mitosis, drosophila salivary mitosis.

 

Mitosis in an onion cell
 

Figure 22 - Anaphase
on a cell of garlic.

 

Model of mitosis MODEL OF MITOSIS

As shown by the text of E. Morholt e P.F. Brandewein (1 p394),
with a piece of electric wire it is possible to make a simple and clear model of mitotic division of a chromosome (figure 23). With this model we can see the separation of the chromatids along the spindle fibers during mitosis.
With reference to the side figure:
a - Take a length of electrical cord with two ends
b - separate them in the middle
c - tie a string to each piece of cord
d - place a rubber band into the strings as indicated
e - now, pull the two strings apart, the "chromosome" will be split into two "chromatids" same as during mitosis.
f - the two "chromatids" slide along one of the fibers of the mitotic spindle, simulated in our model by the rubber band.


FALSIFICATION OF THE SPONTANEOUS GENERATION
Until the end of the 17th century, people believed that little animals like flies and worms could spontaneously be born from substances in decomposition or from mud. Francesco Redi, Lazzaro Spallanzani and Louis Pasteur made experiments which proved the idea of the spontaneous generation was wrong. At your home or in your school you can made such experiments too.
1 - Take two glass jars with a screw top. Put in each a little piece of cooked apple and a spoon of vinegar. For a night, leave one of these jars opened so it can be visited by vinegar (fruit) flies. Close the other jar with the lid and sterilize it by placing it in boiling water in a pressure cooker for a half an hour. After removing it from the cooker, let it cool, leaving it closed. The morning after, let the possible bugs present into the first jar leave and then close it with a fine gauze or a plastic sheet on which you will make some pinholes to allow oxygen to enter. After a few days, you should see some bugs in the first jar, and none in the second one. What has happened in the first jar which has not happened in the second? Some vinegar flies laid eggs in the first jar and from them some new flies are born. In the second jar, even if there had been eggs, these are dead because of high temperature in the pressure cooker. More eggs were not laid because the jar was kept closed. With experiments like this one, you can realize that living beings cannot born from nothing, but they are born from other organisms like them. Fall is the more suited season to do this experiment because vinegar flies are particularly active.
2 - Anyway you can try to adapt this experiment to organisms present at other times of the year. For example, if you place some dry grass in a water glass, in few days a deal of protists will appear. If instead you will put the same material in a close glass pot and if you boil it, nothing will be born. Only some rare thermoresistant microorganisms, bacteria which resist the high temperature of boiling water.
... Uhm, and still there is something which is not working: if any living being comes from another living being, from where has come the first living being from which all others are derived? Can we consider completely falsified the theory of the spontaneous generation with these experiments? Is it possible to assert that, even if the spontaneous generation is not the usual way with which living creatures are born, at least at one time during billions of years it has happened on the Earth or another place in the Universe? It is no accident that there are scientists who study how life began in the first place.
http://www.fwkc.com/encyclopedia/low/articles/s/s024000786f.html  Spontaneous Generation
http://biology.clc.uc.edu/courses/bio114/spontgen.htm  Spontaneous Generation
Internet keywords: spontaneous generation.


EXPERIMENTS WITH PROTISTS
Let us see now how protists and other little animals of ponds react to alteration to their environment.
1 - Some microscopic algae, like the euglena, search out light (phototaxis) and to do this they use an organelle sensible to the light, named stigma. With a dark paper, cover the bottom part of a test tube holding a culture of euglena. The part of the test tube exposed to light should become green, rich with algae. Make the same experiment with other microscopic algae and with protozoa.
2 - Add two or three drop of distilled water to a little water drop collected in a pond and watch what happens to the protists. Very probably you will see them inflate and then explode. This occurs because of the different saline concentration inside and outside the protists and the osmotic pressure which is produced inside their cells.
3 - Protists are sensitive to most chemicals and generally they react by running away; in some cases instead they approach them (chemotaxis). Prepare some microscope slides with protists and observe through the microscope their behavior when you add acidic substances (i.e.: vinegar), basic substances (i.e.: backing soda), glucose, salt, sparkling water (rich of  CO2), broth, milk, tiny grain of cheese, dyes, etc. At the beginning use very low amounts of these substances, then increase their concentration.
4 - From a pond or an aquarium, collect a hydra and place it on a microscope slide with a pair of water drops. Observing this tiny polyp through the microscope, probably you will see some sucker shaped microorganisms (trichodina) moving on its body. Watch what happens after adding a little drop of vinegar to their water! Trichodina will escape from the hydra and probably die. Hydra itself will have launched many of its harmful paralyzing darts.
5 - Submit protists to different stimulus such as light, temperature, electric field (about 5 V in DC). In this last case, some protists will gather on the cathode (the negative - pole). Also amebas are inclined to move towards the cathode. Change the polarity of the current and observe the behavior of the protists.
Internet Keyword: phototaxis chemotaxis protists.


INTERNET RESOURCES

Amateur Scientist Sites  Websites which propose experiments


CONCLUSION

It is not easy to write a conclusion for such a heterogeneous series of experiments. However, we hope you have appreciated this technique of gathering many briefly described experiments in a single article. At least it offers you many choices. We now ask for your help: please report to us the links which are not working any more; tell us about other interesting sites; tell us what experiments you would like to see treated in a more detail; send us other comments and suggestions. You can use the evaluation card below. Will you help us?


BIBLIOGRAPHY

1 E. Morholt, P.F. Brandwein A Sourcebook for the Biological Sciences Saunders College Publishing - Ward's
2 G., L. Durrell The Amateur Naturalist Dorling Kindersley Limited, London
3 C.H. Hampton, C.D. Hampton, D.C. Kramer et al. Classroom Creature Culture: Algae to Anoles National Science Teachers Association
4 C.L. Stong Book of projects for The amateur scientist Simon and Shuster Inc 1960
5 R. Fitter, R. Manuel Collins field guide to freshwater life W. Collins Sons & Co 1986
6 H. Bellmann Leben in Bach und Teich Mosaik Verlag GmbH 1988

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