so animals cannot carry out photosynthesis; ..
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.
Plants are the only photosynthetic organisms to have ..
Respiration refers to the metabolism of oxygen and the release of carbon dioxide. In it is a positive term, a process vital to life. But photorespiration is an entirely negative term because it represents a severe loss to the process of using light energy in photosynthetic organisms to fix carbon for subsequent carbohydrate synthesis. By leading to the loss of up to half of the carbon that has been fixed at the expense of light energy, photorespiration undoes the work of photosynthesis.
The short tenure of the human species marks aturning point in the history of life on Earth. Before theappearance of Homo sapiens, energy was being sequestered morerapidly than it was being dissipated. Then human beings evolved,with the capacity to dissipate much of the energy that had beensequestered, partially redressing the planet's energybalance. The evolution of a species like Homo sapiens may be anintegral part of the life process, anywhere in the universe ithappens to occur. As life develops, autotrophs expand and make aplace for heterotrophs. If organic energy is sequestered insubstantial reserves, as geological processes are bound to do,then the appearance of a species that can release it is all butassured. Such a species, evolved in the service of entropy,quickly returns its planet to a lower energy level. In anevolutionary instant, it explodes and is gone.