Ibn Khaldun statue in TunisTunisia — Sociological reasoning predates the foundation of the discipline. Social analysis has origins in the common stock of Western knowledge and philosophyand has been carried out from as far back as the time of ancient Greek philosopher Platoif not before.
The concept was later extended to include any biological system from the cell to the entire biosphereall the areas of Earth inhabited by living things.
Unity All living organisms, regardless of their uniqueness, have certain biological, chemical, and physical characteristics in common. All, for example, are composed of basic units known as cells and of the same chemical substances, which, when analyzed, exhibit noteworthy similarities, even in such disparate organisms as bacteria and humans.
Furthermore, since the action of any organism is determined by the manner in which its cells interact and since all cells interact in much the same way, the basic functioning of all organisms is also similar.
Animal cells and plant cells contain membrane-bound organelles, including a distinct nucleus. In contrast, bacterial cells do not contain organelles. There is not only unity of basic living substance and functioning but also unity of origin of all living things.
If, however, life originated on Earth more than once in the past, the fact that all organisms have a sameness of basic structure, compositionand function would seem to indicate that only one original type succeeded. A common origin of life would explain why in humans or bacteria—and in all forms of life in between—the same chemical substance, deoxyribonucleic acid DNAin the form of genes accounts for the ability of all living matter to replicate itself exactly and to transmit genetic information from parent to offspring.
Furthermore, the mechanisms for that transmittal follow a pattern that is the same in all organisms. Whenever a change in a gene a mutation occurs, there is a change of some kind in the organism that contains the gene.
It is this universal phenomenon that gives rise to the differences variations in populations of organisms from which nature selects for survival those that are best able to cope with changing conditions in the environment. Evolution itself is a biological phenomenon common to all living things, even though it has led to their differences.
Evidence to support the theory of evolution has come primarily from the fossil recordfrom comparative studies of structure and function, from studies of embryological development, and from studies of DNA and RNA ribonucleic acid.
Three types of natural selection, showing the effects of each on the distribution of phenotypes within a population.
The downward arrows point to those phenotypes against which selection acts. Stabilizing selection left column acts against phenotypes at both extremes of the distribution, favouring the multiplication of intermediate phenotypes.
Directional selection centre column acts against only one extreme of phenotypes, causing a shift in distribution toward the other extreme. Diversifying selection right column acts against intermediate phenotypes, creating a split in distribution toward each extreme.
Diversity Despite the basic biological, chemical, and physical similarities found in all living things, a diversity of life exists not only among and between species but also within every natural population. The phenomenon of diversity has had a long history of study because so many of the variations that exist in nature are visible to the eye.
The fact that organisms changed during prehistoric times and that new variations are constantly evolving can be verified by paleontological records as well as by breeding experiments in the laboratory. Long after Darwin assumed that variations existed, biologists discovered that they are caused by a change in the genetic material DNA.
That change can be a slight alteration in the sequence of the constituents of DNA nucleotidesa larger change such as a structural alteration of a chromosomeor a complete change in the number of chromosomes. In any case, a change in the genetic material in the reproductive cells manifests itself as some kind of structural or chemical change in the offspring.
The consequence of such a mutation depends upon the interaction of the mutant offspring with its environment. It has been suggested that sexual reproduction became the dominant type of reproduction among organisms because of its inherent advantage of variability, which is the mechanism that enables a species to adjust to changing conditions.
New variations are potentially present in genetic differences, but how preponderant a variation becomes in a gene pool depends upon the number of offspring the mutants or variants produce differential reproduction. Thus, when a species is introduced into a new habitatit either adapts to the change by natural selection or by some other evolutionary mechanism or eventually dies off.
Because each new habitat means new adaptationshabitat changes have been responsible for the millions of different kinds of species and for the heterogeneity within each species.
The total number of extant animal and plant species is estimated at between roughly 5 million and 10 million; about 1. The use of classification as a means of producing some kind of order out of the staggering number of different types of organisms appeared as early as the book of Genesis —with references to cattle, beasts, fowl, creeping things, trees, and so on.
The first scientific attempt at classification, however, is attributed to the Greek philosopher Aristotlewho tried to establish a system that would indicate the relationship of all things to each other.
Other schemes that have been used for grouping species include large anatomical similarities, such as wings or fins, which indicate a natural relationship, and also similarities in reproductive structures.
Taxonomy has been based on two major assumptions: Behaviour and interrelationships The study of the relationships of living things to each other and to their environment is known as ecology. Because these interrelationships are so important to the welfare of Earth and because they can be seriously disrupted by human activities, ecology has become an important branch of biology.
Continuity Whether an organism is a human or a bacterium, its ability to reproduce is one of the most important characteristics of life. Because life comes only from preexisting life, it is only through reproduction that successive generations can carry on the properties of a species.
The study of structure Living things are defined in terms of the activities or functions that are missing in nonliving things. The life processes of every organism are carried out by specific materials assembled in definite structures.Dear Twitpic Community - thank you for all the wonderful photos you have taken over the years.
We have now placed Twitpic in an archived state. divided into “a small group of rich men and a great mass of poor engaged in a constant class struggle” (p. ). y. their society in general. Alienated individuals may then treat others as mere objects to be exploited and Critical Theories: Marxist, Conflict, and Feminist -.
Summary: MLA (Modern Language Association) style is most commonly used to write papers and cite sources within the liberal arts and humanities. Biology: Biology, study of living things and their vital processes that deals with all the physicochemical aspects of life.
Modern principles of other fields, such as chemistry, medicine, and physics, for example, are integrated with those of biology in areas such as biochemistry, biomedicine, and biophysics.
Other essays and articles in the Literature Archives related to this topic include: Class and Social Critique in “Arms and the Man" by George Bernard Shaw • The Economics of Socialism. George Bernard Shaw wrote Arms and the Man in during the Victorian era when most plays were lighter dramas or comedies in the vein of The Importance of Being Earnest, which was a play about manners .
Antiquity. Ancient Rome; Ancient Greece; Asia; Babylonia; Medieval Europe; The Muslim World; Byzantine Empire; Ottoman Empire; Crimean Khanate; Topics and practices.