link working environment" class="lazy lazy-hidden alignright size-full wp-image-484" width="220">Lifeliving matter and, as such, matter that shows certain attributes that include responsiveness, growthmetabolismenergy transformationand reproduction.
Although a noun, as with other defined entities, the word life might be better cast as a verb to reflect its essential status as a process. Life comprises individuals, living beings, assignable to groups taxa.
Each individual is composed of one or more minimal living units, called cellsand is capable of transformation of carbon -based and other compounds metabolismgrowth, and participation in reproductive acts.
Life-forms present on Earth today have evolved from ancient common ancestors through the generation of hereditary variation and natural selection. Although some studies state that life may have begun as early as 4.
But this is life as a whole. The several Water Is Life Essay In English of science that reveal the common historical, functional, and chemical basis of the evolution of all life include electron microscopygeneticspaleobiology including paleontologyand molecular biology. The phenomenon of life can be approached in several ways: As far as is known, life exists only on Earth. Most life-forms reside in a thin sphere that extends about 23 km 14 miles from 3 km 2 miles beneath the bottom of the ocean to the top of the troposphere lower atmosphere ; the relative thickness is comparable to a coat of paint on a rubber ball.
An estimated 10—30 million distinguishable species currently inhabit this sphere of life, or biosphere. These include anatomy the study of form at the visible levelultrastructure the study of form at the microscopic levelphysiology the study of functionmolecular biology and biochemistry the study of form and function read more chemical levelsecology the study of the relations of organisms with their environmentstaxonomy the naming, identifying, and classifying of organismsethology the study of animal behaviourand sociobiology the study of social behaviour.
Specific sciences that participate in the study of life focus more narrowly on certain taxa or levels of observation—e. Although the scientists, click at this page, and others Water Is Life Essay In English participate in studies of life easily distinguish living matter from inert or dead matter, none can give a completely inclusiveconcise definition of life itself.
Part of the problem is that the core properties of life—growth, change, reproduction, active resistance to external perturbation, and evolution —involve transformation or the capacity for transformation. Living processes are thus antithetical to a desire for tidy classification or final definition.
To take one example, the number of chemical elements involved with life has increased with time; an exhaustive list of the material constituents of life would therefore be premature. Nonetheless, most scientists implicitly use one or more of the metabolic, physiological, biochemical, genetic, thermodynamic, and autopoietic definitions given below.
Metabolic definitions are popular with biochemists and some biologists. Living systems are objects with definite boundaries, continually exchanging some materials with their surroundings but without altering their general properties, at least over some period of time.
However, there are exceptions. There are frozen seeds and source that remain, so far as is known, perfectly dormant. At low temperatures they lack metabolic activity for hundreds, perhaps thousands, of years but revive perfectly well upon being subjected to more clement conditions.
Similar reactions, incidentally, occur in animals and plants. Flames also have a well-known capacity for growth. These facts underscore the inadequacy of this metabolic definition, even as they suggest the indispensable role of energy transformation to living systems. Physiological definitions of life are popular.
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Life is defined as any system capable of performing functions such as eating, metabolizing, excreting, breathingmoving, growing, reproducing, and responding to click at this page stimuli. But many such properties are either present in machines that nobody is willing to call alive or absent from organisms, such as the dormant hard-covered seed of a treethat everybody is willing to call alive.
An automobile, for example, can be said to eat, metabolize, excrete, breathe, move, and be responsive to external stimuli. A visitor from another planet, judging from the enormous number of automobiles on Earth and the way in which cities and landscapes have been designed for the special benefit of motorcars, might well believe that automobiles are not only alive but are the dominant life-form on the planet. A biochemical or molecular biological definition sees living organisms as systems that contain reproducible hereditary information coded in nucleic acid molecules and that metabolize by controlling the rate of chemical reactions using the proteinaceous catalysts known as enzymes.
In many respects, this is more satisfying than the physiological or metabolic definitions of life. However, even here there are counterexamples. Viruslike agents called prions lack nucleic acids, although the nucleic acids of the animal cells in which they reside may be involved in their reproduction.
Ribonucleic acid RNA molecules may replicate, mutate, and then replicate their mutations in test tubes, although by themselves they are not alive. Furthermore, a definition strictly in chemical terms seems peculiarly vulnerable. It implies that, were a person able to construct a system Water Is Life Essay In English had all the functional properties of life, it would still not be alive if it lacked the molecules that earthly biologists are fond of—and made of.
All organisms on Earthfrom the tiniest cell to the loftiest treesdisplay extraordinary powers. They effortlessly perform complex transformations of organic molecules, exhibit elaborate behaviour patterns, and indefinitely construct from raw materials in the environment more or less identical copies of themselves.
How link systems of such staggering complexity and such stunning beauty ever arise? A main part of the answer, for which today there is excellent scientific evidence, was carefully chronicled by the English naturalist Charles Darwin in the years before the publication in of his epoch-making work On the Water Is Life Essay In English of Species.
A modern rephrasing of his theory of natural selection goes something like this: Hereditary information is carried by large molecules known as genescomposed of nucleic acids. Different genes are responsible for the expression of different characteristics of the organism.
During the reproduction of the organism, the genes also replicate and thereby pass on the instructions for various characteristics to the next generation. Occasionally, there are imperfections, called mutationsin gene replication. A mutation alters the instructions for one or more particular characteristics. The mutation also breeds true, in the sense that its capability for determining a given characteristic of the organism remains unimpaired for generations until the mutated gene is itself mutated.
Some mutations, when Water Is Life Essay In English, will produce characteristics favourable for the organism; organisms with such favourable genes will reproduce preferentially over those without such genes. Most mutations, however, turn out to be deleterious and often lead to some impairment or to death of the organism. To illustrate, it is unlikely that one can improve the functioning of a finely crafted watch by dropping it from a tall building. The watch may perform better, but this is highly improbable.
In this way, organisms slowly evolve toward greater complexity. This evolution occurs, however, only at enormous cost: A genetic definition of life therefore would be a system capable of evolution by natural selection. This definition places great emphasis on the importance of replication.
Replication refers to the capacity of molecules such as deoxyribonucleic acid DNA to precisely copy themselves, whereas reproduction refers to the increase in number of organisms by acts that make a new individual from its parent or parents.
In any organism, enormous biological effort is directed toward reproduction, although it confers no obvious benefit on the reproducing organism itself. However, if life is defined as an entity capable of reproduction, then a mulewhich is clearly alive yet check this out not reproduce, would be excluded from the living under this restrictive definition.
Indeed, many organisms, such as hybrid mammals and plants that are past their prime, do not reproduce even though the individual cells of which they are composed link. Life defined as a reproductive system dependent on replicating components does not rule out synthetic reproduction.
For example, it should be possible to construct a machine that is capable of producing identical copies of itself from preformed building blocks but that arranges its descendants in a slightly different manner when a random change occurs in its instructions.
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Completely free esl sample essays and esl example essay for English composition essay writing. Example English essays for ESL writing. ESL, essay writing, sample. Life: Life, living matter and, as such, matter whose attributes include responsiveness, growth, metabolism, energy transformation, and reproduction. You’ll Succeed Even if the deadline is hard on heels! Professional Essay Writer from cocktail24.info will help you. Coffee won’t help you to write a good essay. Aldo Rossi's Architecture of Recollection: The Silence of Things Repeated or Stated for Eternity by Kurt W. Forster Director The Getty Center for the History of Art.
But the fact that such a machine would satisfy the genetic definition of life is not an argument against such a definition; in fact, if the building blocks were simple enough, the machine would have the capability of evolving into very complex systems that would probably have all the other properties attributed to living systems. The genetic definition has the additional advantage of being expressed purely in source terms; i.
The improbability of contemporary organisms—dealt with more fully below—is so great that these organisms could not possibly have arisen by purely random processes and without historical continuity. Fundamental to the genetic definition of life then seems to be the notion that a certain level of complexity cannot be achieved without natural selection. Thermodynamics distinguishes between isolated, closed, and open systems. An isolated system is separated Water Is Life Essay In English the rest of the environment and exchanges neither light nor heat nor matter check this out its surroundings.
A closed system exchanges energy but not matter. An open system is one in which both material and energetic exchanges occur. The second law of thermodynamics states that, in a closed system, no processes will tend to occur that increase the net organization or decrease the net entropy of the system. Thus, the universe taken as a whole is steadily moving toward a state of complete randomness, lacking any order, Water Is Life Essay In English, or beauty. Living organisms are manifestly organized and at first sight seem to represent a contradiction to the second law of thermodynamics.
Indeed, living systems might then be defined as localized regions where there is a continuous maintenance or increase in organization. Living systems, however, do not really contradict the second law.
PSA! cocktail24.info Has a TON of Scholarship Opportunities Right Now. SPOILER: college is crazy-expensive. Sorry. Did we spoil it? There are. What is the importance of water in our lives? How water is the most useful natural resource on earth? This short essay and speech shows the importance of water for. Inquiry: AN OCCASIONAL COLUMN Life's Little Essential Everybody knows liquid water is necessary for life, at least as we know it. But just why exactly? Try Our Friends At: The Essay Store. Free English School Essays. We have lots of essays in our essay database, so please check back here frequently to see the. A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel.
They increase their organization in regions of energy flow, and, indeed, their cycling of materials and their tendency to grow can be understood only in the context of a more general definition of the second law that applies to open as well as closed and isolated systems. In nature except at cosmic scales, where gravity becomes a crucial factorenergy moves from being concentrated to being spread out; spontaneously occurring complex systems do not violate the second law but help energy spread out, thus producing entropy and reducing gradients.
A general statement of open-system thermodynamics is that nature abhors a gradient, a difference across a distance. Differences and gradients in nature represent improbable, preexisting organizations.
Many complex systems in nature spontaneously arise to degrade gradients and persist until the gradients are nullified. Most life on Earth is dependent on the flow of sunlightwhich is utilized by photosynthetic organisms to construct complex molecules from simpler ones. Some deep-sea and cave organisms called chemoautotrophs depend on chemical gradients, such as the natural energy-producing reaction between hydrogen sulfide bubbling up from vents and oxygen dissolved in water.
The organization of life on Earth can thus be seen as being driven by a natural second-law-based reduction between the energy of the hot Sun and the cooler space around it.
Some Water Is Life Essay In English argue on grounds of quite general open-system thermodynamics that the organization of a system increases as energy flows through it. Moreover, energy flow leads to the development of cycles. An example of a biological cycle on Earth is the carbon cycle. Carbon from atmospheric carbon dioxide is incorporated by photosynthetic or chemosynthetic organisms and converted into carbohydrates through the process of autotrophy.
These carbohydrates are ultimately oxidized by heterotrophic organisms to extract useful energy locked in their chemical bonds. In the oxidation of Water Is Life Essay In English, carbon dioxide is returned to the atmosphere, thus completing the cycle. It has been shown that similar cycles develop spontaneously and in the absence of life by the flow of article source through chemical systems.
Biological cycles may represent natural thermodynamic cycles reinforced by a genetic apparatus. A newer definition of life revolves around the idea of autopoiesis. This idea was put forth by Chilean biologists Humberto Maturana and Francisco Varela and emphasizes the peculiar closure of living systems, which are alive and maintain themselves metabolically whether they succeed in reproduction or not.
Unlike machines, whose governing functions are embedded by human designers, organisms are self-governing. Autopoiesis refers to self-producing, self-maintaining, self-repairing, and self-relational aspects of living systems. Living beings maintain their form by the continuous interchange and flow of chemical components.