Реферат по предмету "Иностранный язык"


Importance Of Monera Essay Research Paper a

Importance Of Monera Essay, Research Paper

a) Production of food: cheese, yogurt, vinegar, wine, sour cream, etc.

b) Industry : cleaning up petroleum, remove waste products from the water,

synthesize drugs and chemicals.

Symbiosis : The interdependence of different species, which are

sometimes called symbionts. There are three main types of symbiosis,

based upon the specific relationship between the species involved:

mutualism, parasitism, and commensalism. Symbiosis that results in

mutual benefit to the interdependent organisms is commonly known as

mutualism. An example of mutualism is the coexistence of certain

species of algae and fungi that together compose lichens. Their close

association enables them to live in extreme environments, nourished

only by light, air, and minerals. Living separately, the alga and

fungus would not survive in such conditions. In parasitism, also known

as antagonistic symbiosis, one organism receives no benefits and is

often injured while supplying nutrients or shelter for the other

organism. Parasites include viruses and bacteria that cause many

diseases; certain protozoans that can infect plants and animals;

tapeworms and flukes that infest the intestinal tracks and internal

organs of animals. The type of symbiosis known as commensalism is a

food-sharing association between two different kinds of nonparasitic

animals, called commensals, that is harmless to both and in many cases

is mutually advantageous. Many commensals are free to separate. Other

commensals function together so completely that they cannot separate.

They do not harm each other. An example is a polyp found in deep water

off the coast of Newfoundland. It attaches itself to the shell of a

certain species of hermit crab and, by budding, covers the entire shell

with a colony that dissolves the original shell. Because the colony

grows at the same rate as the crab, it furnishes continuous protection,

and the crab does not shed its shell at periodic intervals as it

normally would. The polyp, in turn, benefits by moving about with the

crab, thereby obtaining a greater food supply than it would if attached

to a stationary object.

Uses of Bacteria in the Environment :

Bacteria feed on dying material and convert it back into basic

substances. This process of decomposition is as significant as

photosynthesis, for without it food chains would cease, and fallen

trees, leaves, and other refuse would simply pile up. Bacteria also

strongly influence the movement of key elements, such as sulfur, iron,

phosphorus, and carbon, around the globe. The weathering of rocks,

which releases elements back into life systems for use, is

substantially enhanced by the breakdown processes of bacteria.

Uses of Bacteria in Sewage Disposal : The main cleansing agents in

sewage treatment are a variety of specialized bacteria that convert,

mostly through fermentation, the organic materials of sewage into

carbon dioxide, methane, and hydrogen gases. There is a bacterial

species involved with the production of nearly every familiar product.

For example, vinegar, which is used as both a flavor enhancer and an

important food preservative, results from the conversion of ethyl

alcohol to acetic acid by acetic-acid bacteria. Specific enzymes

extracted from bacteria are used in spot removers, meat tenderizers,

laundry starches, and household detergents. Bacteria are now used

throughout the growing biotechnology industry in the development of new

products for medical treatment. Bacteria that can digest petroleum are

even used in oil-spill cleanups.

Nitrogen Fixation : Biological or industrial process by which

molecular atmospheric nitrogen is converted into a chemical compound

that is essential for plant growth and is also used in industrial

chemical production.

The most widely used and most productive of the soil microorganisms

capable of nitrogen fixation are symbiotic bacteria of the genus

Rhizobium, which colonize and form nodules on the roots of leguminous

plants such as clover, alfalfa, and peas. These bacteria obtain food

from the legume, which in turn is supplied with abundant nitrogen

compounds. Soils are sometimes inoculated with a particular species of

Rhizobium to increase a legume crop, which is often planted to

replenish the nitrogen depleted by other crops.

Much smaller amounts of nitrogen are fixed in the soil by nonsymbiotic (free-living) bacteria such as the aerobes, which function in the presence of oxygen, and bacteria of the genera Klebsiella and Bacillus, which function without oxygen. Some forms of cyanobacteria (formerly known as blue-green algae) also fix nitrogen, such as the alga Anabaena, which, in symbiosis with the water fern Azolla pinnata, is said to markedly increase rice yields, as was the case in paddies in the Th?i B?nh region of northern Vietnam. The need for fixed nitrogen in agriculture today is far greater than can be supplied by natural biological processes, and the production of nitrogen compounds from atmospheric nitrogen is a major chemical industry.




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