ECOSYSTEM

Would do you like to know about Ecosystem?

We humans tend to think of ourselves as visitor to nature places where plants and animals live, but not us. This view of ourselves is an illusion, for we are closely connected to other kinds of organisms in a complex web of life. The interconnections among all organisms on earth become evident when something goes wrong. An example is the explosion that blew up a nuclear reactor in Chernobyl, Ukraine, in 1986. Nine tons of radioactive atoms, chiefly iodine and cesium, were spewed into the air. This amount is roughly a hundred times more than the amount of radioactivity released by atomic bombs dropped on Japan during World War II. While the Chernobyl explosion was a major human disaster, it provided an unusual opportunity for researchers to trace the movements of atoms through nature. Migrations of the radioactive atoms were traced by using ma-chines called Geiger counters. The atoms fell to earth in rain and snow, mostly in northern parts of Scandinavia, which are downwind of Chernobyl. In these regions of tundra, lichens were the first to accumulate the radioactive atoms, and they did so in large quantities. Lichens, which are formed of fungi and unicellular algae, turn out to be "radiation sponges," since they acquire nutrients directly from the air. Later, algae and plants also accumulated radioactive atoms, from lake water and soil. High concentrations of radioactivity then turned up in caribou, which feed mainly on lichens in the tundra. Radioactive atoms also turned up in geese, which feed on algae, and in cows, which feed on plants. Later the atoms appeared in the predators of these animals: wolves, foxes, and humans. In some of the people, the radioactivity caused birth defects, immune deficiencies that resemble AIDS, thyroid cancers, and leukemia. Atoms move continually from the soil, water, and air to various kinds of organisms, including humans, and then back again to the nonliving environment. One year they are part of an elephant, a few years later part of a shark, and then a palm tree, beetle, chicken, and human. Organ-isms and their physical environment are interconnected by the atoms they share. 

Do you know what is Ecosystem Components?

Biologists subdivide nature into ecosystems. Each ecosystem consists of a set of interacting populations together with aspects of the physical environment. It is a functional unit of nature, through which energy and atoms move as plants and algae build organic molecules and other organisms eat them. A particular meadow, lake, or woods, for example, is an ecosystem. No ecosystem is isolated from others, since materials travel from place to place within the air, water, and organ-isms. A molecule of carbon dioxide used by a woodland violet may have been released in the breath of a desert bobcat. Moreover, there are no clear boundaries between adjacent ecosystems. A fox, for example, may be a component of two ecosystems, capturing rabbits in a meadow and chipmunks in a nearby pine forest. 

 What does mean by organisms?

 

The millions of organisms within an ecosystem are grouped according to how they acquire organic monomers. Organic monomers , are small molecules from which larger molecules, called polymers , are constructed. Important monomers are glucose, amino acids, fatty acids, and nucleotides. They are used by cells to build proteins, polysaccharides, lipids, and nucleic acids. An ecosystem has three groups of organisms: producers, consumers, and decomposers. 

Producers   A producer is an organism that builds its own monomers from inorganic materials. Most producers build sugars by photosynthesis; they are plants, unicellular algae, and photosynthetic bacteria. (A few build sugars by chemosynthesis, using the energy of in-organic molecules.) Producers use some of the sugar for energy and convert the rest into amino acids, fatty acids, and other kinds of monomers. All the organic monomers within an ecosystem originate with the producers, as only they can build organic molecules from inorganic materials. In an oak forest ecosystem, for example, mosses, wildflowers, shrubs, and trees synthesize sugar and convert some of it into other kinds of monomers. They join these monomers to form cellulose, starch, enzymes, cell membranes, and other components of cells. The cells, in turn, form leaves, stems, roots, and seeds.
 
Consumers   A consumer acquires its monomers from other live organisms. It consumes other forms of life and digests their polymers into monomers: 
The monomers move into the consumer's cells, where they are used as sources of energy and building blocks for constructing the consumer's own kinds of polymers. All animals are consumers, as are some fungi, protista, and bacteria. An oak forest ecosystem, for example, has many consumers. There are rabbits and caterpillars, which eat leaves; foxes, which eat rabbits; warblers, which eat cater-pillars; and hawks, which eat warblers. In the forest soil, insects, spiders, mites, fungi, and protozoa consume tiny soil organisms. Consumers are grouped according to the general type of organisms they consume. Herbivores eat producers; primary carnivores eat herbivores; secondary carnivores eat primary carnivores; tertiary carnivores eat secondary carnivores; and so on. A carnivore that is not eaten by any other consumer is a top carnivore in the ecosystem. Mountain lions, wolves, eagles, large mouth bass, and tuna are examples of top carnivores.

Decomposers   A decomposer acquires monomers from dead organisms, the parts of organisms (e. g., fallen leaves and feathers), and feces. It uses these monomers as sources of energy, and for building its own kinds of polymers, excreting what it cannot use into the surrounding environment. Earthworms, many fungi, and many bacteria are important decomposers. Scavengers are large decomposers, such as hyenas, pigs, vultures, ravens, and sharks. Most scavengers eat living animals as well as dead ones. They are both carnivores and decomposers. Decomposers transfer organic molecules from dead materials into their own bodies and convert them ulti-mately to inorganic materials, which they release into the environment. This process, called decomposition, makes inorganic

molecules and ions available again to the producers. Without decomposers, the atoms of life would be-come tied up in dead organisms, and the producers would have no raw materials for building new organic monomers. In the oak forest ecosystem, a dead leaf falls to the ground and is decomposed by soil organisms.Many kinds of decomposers feed on the leaf, each specialized for digesting certain kinds of molecules. Fungi arrive early and digest the softer parts, leaving the leaf skeleton. Then come bacteria, which digest the tougher molecules of the skeleton. As the bacteria feed, they are eaten, along with the leaf skeleton, by earthworms. Inside the earthworms, some of the skeleton is digested and some passes out of the digestive tract, along with the bacteria, as earthworm feces. The feces are eaten again and again by earthworms and other soil animals until all the molecules of the leaf are digested.