The term coitus is derived from the Latin word coitio or coire, meaning "a coming together or joining together" or "to go together", and it describes a variety of sexual activities under ancient Latin names, but usually refers exclusively to penile—vaginal penetration. Lerner and Laurence Steinberg state that researchers also "rarely disclose how they define sex or even whether they resolved potential discrepancies in definitions of sex".
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.
|Subscribe To||If there are more than two participants in the sex act, it may be referred to as group sex. Autoerotic sexual activity can involve use of dildosvibratorsanal beadsand other sex toysthough these devices can also be used with a partner.|
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|Biological Sciences < University of Chicago Catalog||The faculty of the College believe that a sound knowledge of biology is essential for understanding the world in which we live, engaging many pressing problems facing humanity, and becoming a part of their eventual solution. The Biological Sciences Collegiate Division, therefore, provides a variety of general education courses for all College students—prospective biologists and non-biologists alike.|
There is not only unity of basic living substance and functioning but also unity of origin of all living things. If, Biological foundations of adult sexual development, 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.Biological Foundations of Adult Sexual Development Paper There is no question that human behavior is influenced by different factors such as hormones as well as other chemicals produced by various tissues or glands throughout the body.
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Go ahead and practice some passage-based questions! Understanding adult development is an important step in the process of understanding how societies function.
This lesson will focus on three. An Arrow Indicates Your Location. MyBrainNotes™.com. HOME EXPLORE SITE OUTLINE BROWSE BOOKS CONTACT ME.
Book Reviews and Excerpts About Evolution, Cognition, and the Neurobiology of Behavior. SACRED CONGREGATION FOR CATHOLIC EDUCATION EDUCATIONAL GUIDANCE IN HUMAN LOVE. Outlines for sex education INTRODUCTION. 1. The harmonious development of the human person progressively reveals in each of us the image of a .