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Free effect of temperature on photosynthesis ..
Let us see now how protists and other little animals of ponds react to alteration to theirenvironment.
1 - Some microscopic algae, like the euglena, search out light (phototaxis) and to do thisthey use an organelle sensible to the light, named stigma. With a dark paper, cover thebottom part of a test tube holding a culture of euglena. The part of the test tube exposedto light should become green, rich with algae. Make the same experiment with othermicroscopic algae and with protozoa.
2 - Add two or three drop of distilled water to a little water drop collected in a pondand watch what happens to the protists. Very probably you will see them inflate and thenexplode. This occurs because of the different saline concentration inside and outside theprotists and the osmotic pressure which is produced inside their cells.
3 - Protists are sensitive to most chemicals and generally they react by running away; insome cases instead they approach them (chemotaxis). Prepare some microscope slides withprotists 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 thebeginning 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 apair of water drops. Observing this tiny polyp through the microscope, probably you willsee some sucker shaped microorganisms (trichodina) moving on its body. Watch what happensafter adding a little drop of vinegar to their water! Trichodina will escape from thehydra and probably die. Hydra itself will have launched many of its harmful paralyzingdarts.
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 (thenegative - pole). Also amebas are inclined to move towards the cathode. Change thepolarity of the current and observe the behavior of the protists.
Internet Keyword: phototaxis chemotaxis protists.
A lot of organisms emit light. Of course you know fireflies, but there are also otherluminescent organisms such as some fishes, mushrooms, bacteria, dinoflagellates, andshellfishes. The culture of luminescent bacteria is not difficult. What you have to do isto get a strain of luminescent and harmless bacteria and raise it in a suitable culturemedium. A bacterium widely cultured and used also for lessons in schools is the Photobacteriumphosphoreum, now renamed: Vibrio phosphoreum.
Search for information about the mechanism of the bioluminescence. You can findinformation for this culture and general information on the Internet at sites listedlater. There is a lot of information on bioluminescence on the Internet. There are evenamateur sites devoted to this topic. You can buy the Vibrio phosphoreum at commercially,such as the ATCC (American Type Culture Collection) .You can find other firms of this type on the Internet, using the keywords: culturecollection. Also try the links for the protists experiment. These companies also supplythe culture media and in their sites you can often read their composition.
: In these experiments, need thehelp of a biologist to avoid culturing dangerous microorganisms. Even with help, keep thecultures only for a short time, wash your hands, wash and disinfect all tools which havebeen in contact with the cultures.
Utilisation Pedagogique de Bacteries Luminescentes (in French)
Bioluminescence in Plankton and Nekton (there is a list of luminescent organisms)
Flash! Bacterial illumination
Isolation of Pure Cultures Of Bacteria (Please, read the safety warnings present inthis website)
Bioluminescence Web sites
Internet Keyword: luminous bacteria luminescent bioluminescence luciferin luciferase.
To find companies which sell strains of microorganisms use the keywords: culturecollection.
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 littleheat, the iron produces only heat. Put both on a table. Keep them at least a meter (abouta yard) apart and with the emitting surfaces turned away from you. Note the differentbehavior of insects. Mask the lamp with plastic sheets of different colors and verify ifbugs are more attracted to a particular color. This is also a method to capture nighttimeinsects, particularly moths, so you can observe them with a lens or a stereoscopicmicroscope.
effects of increased temperature and co 2 on photosynthesis, ..
For the past 26 years, strings of subterranean electrical wires have heated segments of the forest floor to an unnatural temperature. It's the longest running experiment of its kind, and a time machine of sorts—a way for ecologists to study how the soil will respond to changes in global temperatures, which are projected to rise an estimated 5 degrees Celsius (9 degrees Fahrenheit) by the end of the century. The world’s soils are important because they contain two to three times more carbon than the atmosphere. Now, results from this experiment have shown that rising temperatures could cause the soil to release that carbon, accelerating global warming in a reinforcing feedback loop.
Melillo says these phases suggest microbes in the soil are “reorganizing" their genetic material to adapt to the changing soil temperatures. Using DNA and RNA sequencing tools, the researchers have been able to identify what kinds of microbes are at work and how they are consuming various “stocks” of carbon in the soil. But in the past 26 years, the soil in the heated plots has lost 17 percent of its carbon.
Pearson - The Biology Place - Prentice Hall Bridge page
Until the end of the 17th century, people believed that little animals like flies andworms could spontaneously be born from substances in decomposition or from mud. FrancescoRedi, Lazzaro Spallanzani and Louis Pasteur made experiments which proved the idea of thespontaneous generation was wrong. At your home or in your school you can made suchexperiments too.
1 - Take two glass jars with a screw top. Put in each a little piece of cooked apple and aspoon of vinegar. For a night, leave one of these jars opened so it can be visited byvinegar (fruit) flies. Close the other jar with the lid and sterilize it by placing it inboiling 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 thefirst jar leave and then close it with a fine gauze or a plastic sheet on which you willmake some pinholes to allow oxygen to enter. After a few days, you should see some bugs inthe first jar, and none in the second one. What has happened in the first jar which hasnot happened in the second? Some vinegar flies laid eggs in the first jar and from themsome new flies are born. In the second jar, even if there had been eggs, these are deadbecause of high temperature in the pressure cooker. More eggs were not laid because thejar was kept closed. With experiments like this one, you can realize that living beingscannot born from nothing, but they are born from other organisms like them. Fall is themore 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 theyear. For example, if you place some dry grass in a water glass, in few days a deal ofprotists will appear. If instead you will put the same material in a close glass pot andif 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 fromanother living being, from where has come the first living being from which all others arederived? Can we consider completely falsified the theory of the spontaneous generationwith these experiments? Is it possible to assert that, even if the spontaneous generationis not the usual way with which living creatures are born, at least at one time duringbillions of years it has happened on the Earth or another place in the Universe? It is noaccident that there are scientists who study how life began in the first place.
Internet keywords: spontaneous generation.
If placed in a suitable nutrient environment, cells and tissues of many organisms are ableto 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 toprepare a nutritive and sterilized culture medium for the piece of plant tissue. Keep theculture in the suitable conditions of light and temperature and which vary from plant toplant. Over many days, you will observe the growth of a callus or roots or shoots. In thisway you can obtain even whole plants (cloning). These experiments show that special cellskeep all the information necessary to generate the whole plant.
As we have mentioned, it is necessary avoid bacteria and moulds in the cultures. For thisyou will need sterilize tools, vials, tubes, and nutrient medium. Place each in anautoclave for a ten minutes or, lacking an autoclave, a pressure cooker. The tissues aswell 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 ofwind and dust as possible. The culture medium should contain water, vitamins (particularlythose of the B-complex. For this, use yeast extract), sugars, mineral salts. To enrich thewater with mineral salts, boil some water with a handful of soil, then let settle andfilter it. Usually, people also insert 0.5-0.8% of agar-agar to "solidify" themedium. 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 invitro culture of vegetable tissues. In fact you can propagate a lot of plants in thisway. 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 tissuesof roots, stems, apical buds, shoots, leaves, even single cells. Each plant and tissue hasits own needs. They are different from each other. You can try the influence of thevegetable hormones, special nutrients, etc.
This field is very broad and complex so, if you are interested in continuing with theseexperiments, you can buy special books and you should build a sterile box.
Plant Tissue Culture for the Gardener
Basic Principle in Plant Tissue Culture Technique
Plant Tissue Culture Kit Manual
Plant Micropropagation Using African Violet Leaves
Plant Tissue Culture (links)
Internet keywords: in vitro culture plant tissue micropropagation.
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Science Experiments on Environmental Education and Biology
plant to keep on photosynthesising at a steady rate there needs to be
plenty of water and the temperature needs to be kept at a certain
level because once carbon dioxide is no longer the limiting factor
simply giving the plant more wont have any effect.
ANALYSIS OF THE SOIL COMPOSITION
Variables: The variables that might affect the rate of photosynthesis in this experiment are: Temperature: When the temperature rises so does the rate of photosynthesis; this is because as the temperature around the plant rises the enzymes controlling photosynthesis inside the chloroplasts heat up and start moving around faster, the fast moving molecules collide with other fast moving enzymes causing them to react....
The soil is composed of many different sized particles
Because we need the experiment to be a fair
one and we know from our research that temperature can affect the rate
of photosynthesis we needed to cut down the heat transferring from the
light to our experiment as much as we can.
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