<p><strong><font size="3">Biology</font></strong> (from Greek: &beta;ί&Icirc;&macr;&omicron;&sigmaf;, <em>bio</em>, &quot;life&quot;; and &lambda;ό&Iuml;Œ&gamma;&omicron;&sigmaf;, <em>logos</em>, &quot;knowledge&quot;) is the study of life.&nbsp;<a title="Life" href="http:br />Biology is an information science that is close to computer science and mathematics.&nbsp;Biologists collect information through experiments on how molecules pass signals and regulate genetic elements through feedback systems.&nbsp;<br /><br /en>The outcomes are usually databases and new gene markers and drug targets. The purpose of biology is to understand life in terms of how they process information in the physical world.wikipediaThe major application of biology is medicine.orgTherefore, biology is sometimes called the basic sience of medicine.<br /wiki><br /Life">lifeThe early 2000s was at the point where the conventional views of molecular biology changed rapidly with new views. One of them is the transition from the object-oriented understanding of biology to an interaction-oriented understanding.&nbsp;<br />Many scientists have predicted the reverse of reductionism in biology in the past, and such interaction-based molecular research is the starting point of aholistic way.&nbsp;<br />The most appropriate and general name of such a non-reductionist methodology of doing biology is perhaps omics. We now have enough individual objects in biology to look at the architecture of the biological information object networks. &nbsp;[[Network biology]] and [[systems biology]] are sub branches of biology where [[omics]] paradigm is applied.<br /><br />It contains such topics as classifying the various forms of organisms, how species come into <a title="Existence" href="http://en.wikipedia.org/wiki/Existence">existence</a>, and the interactions they have with each other and with the <a title="Natural environment" href="http://en.wikipedia.org/wiki/Natural_environment">natural environment</a>. Biology encompasses a broad spectrum of academic fields that are often viewed as independent disciplines. However, together they address <a title="Phenomenon" href="http://en.wikipedia.org/wiki/Phenomenon">phenomena</a> related to <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">living organisms</a> (biological phenomena) over a wide range of disciplines, many of which, for example, <a title="Botany" href="http://en.wikipedia.org/wiki/Botany">botany</a>, <a title="Zoology" href="http://en.wikipedia.org/wiki/Zoology">zoology</a>, and <a title="Medicine" href="http://en.wikipedia.org/wiki/Medicine">medicine</a> are considered ancient fields of study.</p><p>Biology as a unified <a title="Science" href="http://en.wikipedia.org/wiki/Science">science</a> was first developed in the nineteenth century, as scientists discovered that all living things shared certain fundamental characteristics and were best studied as a whole. Over a million papers are published annually in a wide array of biology and medicine <a title="Academic journal" href="http://en.wikipedia.org/wiki/Academic_journal">journals</a>,<sup class="reference" id="_ref-0"><a title="" href="http://en.wikipedia.org/wiki/Biology#_note-0">[1]</a></sup> and biology is a standard subject of instruction at schools and universities around the world.</p><p>As such a vast field, biology is divided into a number of disciplines. The old divisions by type of organism remains with subjects such as <a title="Botany" href="http://en.wikipedia.org/wiki/Botany">botany</a> encompassing the study of plants, <a title="Zoology" href="http://en.wikipedia.org/wiki/Zoology">zoology</a> with the study of animals, and <a title="Microbiology" href="http://en.wikipedia.org/wiki/Microbiology">microbiology</a> as the study of microorganisms. The field may also be divided based on the scale at which it is studied: <a title="Biochemistry" href="http://en.wikipedia.org/wiki/Biochemistry">biochemistry</a> examines the fundamental chemistry of life; <a title="Cellular biology" href="http://en.wikipedia.org/wiki/Cellular_biology">cellular biology</a> examines the basic building block of all life, the <a title="Cell (biology)" href="http://en.wikipedia.org/wiki/Cell_%28biology%29">cell</a>; <a title="Physiology" href="http://en.wikipedia.org/wiki/Physiology">Physiology</a> examines the mechanical and physical functions of an organism; and <a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">ecology</a> examines how various organisms interrelate. Applied fields of biology such as medicine are more complex and involve many specialized sub-disciplines.</p><table summary="Contents" class="toc" id="toc"> <tbody> <tr> <td> <div id="toctitle"> <h2>Contents</h2> <span class="toctoggle">[<a id="togglelink" class="internal" href="javascript:toggleToc()">hide</a>]</span></div> <ul> <li class="toclevel-1"><a href="http://en.wikipedia.org/wiki/Biology#Foundations_of_modern_biology"><span class="tocnumber">1</span> <span class="toctext">Foundations of modern biology</span></a> <ul> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Cell_Theory"><span class="tocnumber">1.1</span> <span class="toctext">Cell Theory</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Evolution"><span class="tocnumber">1.2</span> <span class="toctext">Evolution</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Gene_theory"><span class="tocnumber">1.3</span> <span class="toctext">Gene theory</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Homeostasis"><span class="tocnumber">1.4</span> <span class="toctext">Homeostasis</span></a></li> </ul> </li> <li class="toclevel-1"><a href="http://en.wikipedia.org/wiki/Biology#Scope"><span class="tocnumber">2</span> <span class="toctext">Scope</span></a> <ul> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Common_descent"><span class="tocnumber">2.1</span> <span class="toctext">Common descent</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Structure_of_life"><span class="tocnumber">2.2</span> <span class="toctext">Structure of life</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Physiology_of_organisms"><span class="tocnumber">2.3</span> <span class="toctext">Physiology of organisms</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Diversity_and_evolution_of_organisms"><span class="tocnumber">2.4</span> <span class="toctext">Diversity and evolution of organisms</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Taxonomy"><span class="tocnumber">2.5</span> <span class="toctext">Taxonomy</span></a></li> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Interactions_of_organisms"><span class="tocnumber">2.6</span> <span class="toctext">Interactions of organisms</span></a></li> </ul> </li> <li class="toclevel-1"><a href="http://en.wikipedia.org/wiki/Biology#History"><span class="tocnumber">3</span> <span class="toctext">History</span></a></li> <li class="toclevel-1"><a href="http://en.wikipedia.org/wiki/Biology#See_also"><span class="tocnumber">4</span> <span class="toctext">See also</span></a></li> <li class="toclevel-1"><a href="http://en.wikipedia.org/wiki/Biology#References"><span class="tocnumber">5</span> <span class="toctext">References</span></a></li> <li class="toclevel-1"><a href="http://en.wikipedia.org/wiki/Biology#Further_reading"><span class="tocnumber">6</span> <span class="toctext">Further reading</span></a></li> <li class="toclevel-1"><a href="http://en.wikipedia.org/wiki/Biology#External_links"><span class="tocnumber">7</span> <span class="toctext">External links</span></a> <ul> <li class="toclevel-2"><a href="http://en.wikipedia.org/wiki/Biology#Journal_links"><span class="tocnumber">7.1</span> <span class="toctext">Journal links</span></a></li> </ul> </li> </ul> </td> </tr> </tbody></table><script type="text/javascript">//<![CDATA[ if (window.showTocToggle) { var tocShowText = "show"; var tocHideText = "hide"; showTocToggle(); } //]]></script><p><a id="Foundations_of_modern_biology" name="Foundations_of_modern_biology"></a></p>

<p>Biology is a branch of <a title="Science" href="http://en.wikipedia.org/wiki/Science">science</a> that characterizes and investigates living organisms utilizing the <a title="Scientific method" href="http://en.wikipedia.org/wiki/Scientific_method">scientific method</a>. There are four broad unifying principles of biology:</p>

<li>Cell theory. All living organisms are composed of at least one cell and the cell is the basic unit of function in all organisms. In addition, the chemical composition of all cells in all organisms is similar, and emerge from preexisting cells through cell division or <a title="Mitosis" href="http://en.wikipedia.org/wiki/Mitosis">mitosis</a>.</li> <li>Evolution. Through <a title="Natural selection" href="http://en.wikipedia.org/wiki/Natural_selection">natural selection</a> or <a title="Genetic drift" href="http://en.wikipedia.org/wiki/Genetic_drift">genetic drift</a>, a population's inherited traits change from generation to generation.</li> <li>Gene theory. A living organism's traits are encoded into <a title="DNA" href="http://en.wikipedia.org/wiki/DNA">DNA</a> that is the fundamental component of genes. In addition, genes transfer an organism's traits from one generation to the next.</li> <li>Homeostasis. The physiological processes that allow an organism to maintain its internal environment notwithstanding its external environment.</li>

<dl><dd><div class="noprint"><em>Main article: <a title="Cell theory" href="http://en.wikipedia.org/wiki/Cell_theory">Cell theory</a></em></div></dd></dl><p>Cell theory states that all living things are composed of one or more cells as well as the <a title="Secretion" href="http://en.wikipedia.org/wiki/Secretion">secreted</a> products of those cells, for example, <a title="Plasma" href="http://en.wikipedia.org/wiki/Plasma">plasma</a>, <a title="Extracellular matrix" href="http://en.wikipedia.org/wiki/Extracellular_matrix">extracellular matrix</a>, and <a title="Bone" href="http://en.wikipedia.org/wiki/Bone">bone</a>. These cells arise from other cells through <a title="Cell division" href="http://en.wikipedia.org/wiki/Cell_division">cell division</a>, and that in multicellular organisms, every cell in the organism's body has been produced from the single cell in a fertilized egg.</p><p><a id="Evolution" name="Evolution"></a>&nbsp;</p><h3><span class="mw-headline">[[Evolution]]</span></h3><dl><dd><div class="noprint"><em>Main article: <a title="Evolution" href="http://en.wikipedia.org/wiki/Evolution">Evolution</a></em></div></dd></dl><p>A central organizing concept in biology is that all life has a common origin and has changed and developed through the process of the theory of <a title="Evolution" href="http://en.wikipedia.org/wiki/Evolution">evolution</a> (see <a title="Common descent" href="http://en.wikipedia.org/wiki/Common_descent">Common descent</a>). This has led to the striking similarity of units and processes discussed in the previous section. <a title="Charles Darwin" href="http://en.wikipedia.org/wiki/Charles_Darwin">Charles Darwin</a> established evolution as a viable theory by articulating its driving force, <a title="Natural selection" href="http://en.wikipedia.org/wiki/Natural_selection">natural selection</a> (<a title="Alfred Russel Wallace" href="http://en.wikipedia.org/wiki/Alfred_Russel_Wallace">Alfred Russel Wallace</a> is recognized as the co-discoverer of this concept). Darwin theorized that species and breeds developed through the processes of <a title="Natural selection" href="http://en.wikipedia.org/wiki/Natural_selection">natural selection</a> as well as by <a title="Artificial selection" href="http://en.wikipedia.org/wiki/Artificial_selection">artificial selection</a> or <a title="Selective breeding" href="http://en.wikipedia.org/wiki/Selective_breeding">selective breeding</a>.<a title="Genetic drift" href="http://en.wikipedia.org/wiki/Genetic_drift">Genetic drift</a> was embraced as an additional mechanism of evolutionary development in the <a title="Modern synthesis" href="http://en.wikipedia.org/wiki/Modern_synthesis">modern synthesis</a> of the theory.</p><p>The evolutionary history of a <a title="Species" href="http://en.wikipedia.org/wiki/Species">species</a>&mdash; which describes the characteristics of the various species from which it descended&mdash; together with its genealogical relationship to every other species is called its <a title="Phylogeny" href="http://en.wikipedia.org/wiki/Phylogeny">phylogeny</a>. Widely varied approaches to biology generate information about phylogeny. These include the comparisons of <a title="DNA sequence" href="http://en.wikipedia.org/wiki/DNA_sequence">DNA sequences</a> conducted within <a title="Molecular biology" href="http://en.wikipedia.org/wiki/Molecular_biology">molecular biology</a> or <a title="Genomics" href="http://en.wikipedia.org/wiki/Genomics">genomics</a>, and comparisons of <a title="Fossil" href="http://en.wikipedia.org/wiki/Fossil">fossils</a> or other records of ancient organisms in <a title="Paleontology" href="http://en.wikipedia.org/wiki/Paleontology">paleontology</a>. Biologists organize and analyze evolutionary relationships through various methods, including <a title="Phylogenetics" href="http://en.wikipedia.org/wiki/Phylogenetics">phylogenetics</a>, <a title="Phenetics" href="http://en.wikipedia.org/wiki/Phenetics">phenetics</a>, and <a title="Cladistics" href="http://en.wikipedia.org/wiki/Cladistics">cladistics</a> (The major events in the evolution of life, as biologists currently understand them, are summarized on this <a title="Evolutionary timeline" href="http://en.wikipedia.org/wiki/Evolutionary_timeline">evolutionary timeline</a>).<br clear="right" />

<p>Ever since its articulation by Darwin and Wallace, the theory of evolution by natural selection has come under attack by people who disagree with scientific findings or interpretations regarding the origins and diversity of life, generally favoring instead religious explanations. See <a title="Creation-evolution controversy" href="http://en.wikipedia.org/wiki/Creation-evolution_controversy">Creation-evolution controversy</a> for more information.</p><p>Up into the <a title="19th century" href="http://en.wikipedia.org/wiki/19th_century">19th century</a>, it was commonly believed that life forms could appear spontaneously under certain conditions (see <a title="Abiogenesis" href="http://en.wikipedia.org/wiki/Abiogenesis">abiogenesis</a>). This misconception was challenged by <a title="William Harvey" href="http://en.wikipedia.org/wiki/William_Harvey">William Harvey</a>'s diction that &quot;all life [is] from [an] egg&quot; (from the <a title="Latin" href="http://en.wikipedia.org/wiki/Latin">Latin</a> &quot;<a title="Omne vivum ex ovo" href="http://en.wikipedia.org/wiki/Omne_vivum_ex_ovo">Omne vivum ex ovo</a>&quot;), a foundational concept of modern biology. It simply means that there is an unbroken continuity of life from its initial origin to the present time.</p><p>A group of organisms shares a <a title="Common descent" href="http://en.wikipedia.org/wiki/Common_descent">common descent</a> if they share a common <a title="Ancestor" href="http://en.wikipedia.org/wiki/Ancestor">ancestor</a>. All <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organisms</a> on the <a title="Earth" href="http://en.wikipedia.org/wiki/Earth">Earth</a> have been and are descended from a common ancestor or an ancestral <a title="Gene pool" href="http://en.wikipedia.org/wiki/Gene_pool">gene pool</a>. This last universal common ancestor of all organisms is believed to have appeared about <a title="Timeline of evolution" href="http://en.wikipedia.org/wiki/Timeline_of_evolution">3.5 billion years ago</a>. Biologists generally regard the universality of the <a title="Genetic code" href="http://en.wikipedia.org/wiki/Genetic_code">genetic code</a> as definitive evidence in favor of the theory of universal common descent (UCD) for all <a title="Bacterium" href="http://en.wikipedia.org/wiki/Bacterium">bacteria</a>, <a title="Archaea" href="http://en.wikipedia.org/wiki/Archaea">archaea</a>, and <a title="Eukaryote" href="http://en.wikipedia.org/wiki/Eukaryote">eukaryotes</a> (see: <a title="Origin of life" href="http://en.wikipedia.org/wiki/Origin_of_life">origin of life</a>).</p><p><a id="Gene_theory" name="Gene_theory"></a>&nbsp;</p>

<div class="thumbinner" style="width: 182px;"><img width="180" height="260" class="thumbinnerthumbimage"><a titlealt="Schematic representation of DNA, the primary genetic material." class="internal" hreflongdesc="http://en.wikipedia.org/wiki/Image:DNA-structure-and-bases.png"><img width="180" height="260" src="http://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/DNA-structure-and-bases.png/180px-DNA-structure-and-bases.png" class="thumbimage" longdesc="/wiki/Image:DNA-structure-and-bases.png" alt="Schematic representation of DNA, the primary genetic material." /></a>

<div style="float: right;" class="magnify"><a titlestyle="Enlarge" class="internal" href="httpfloat://en.wikipedia.org/wiki/Image:DNA-structure-and-bases.pngright;"><img width="15" height="11" alt="" src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" /></a></div>Schematic representation of <a title="DNA" href="http://en.wikipedia.org/wiki/DNA">DNA</a>, the primary <a title="Genetic material" href="http://en.wikipedia.org/wiki/Genetic_material">genetic material</a>.</div></div>

<dl><dd><div class="noprint"><em>Main article: <a title="Life" href="http://en.wikipedia.org/wiki/Life">Life</a></em></div></dd></dl><p>While organisms may vary immensely in appearance, habitat, and behaviour it is a central principle of biology that all life shares certain universal fundamentals. A key feature is reproduction or replication. The According to <a href="javascript:void(0);/*1256199523180*/">paper writing</a>, the entity being replicated, the replicator, in the past was considered to be the organism during the time of Darwin, but since the 1970s increasingly reduced to the scale of molecules.<sup class="reference" id="_ref-1"><a title="" href="http://en.wikipedia.org/wiki/Biology#_note-1">[2]</a></sup> All known life has a <a title="Carbon" href="http://en.wikipedia.org/wiki/Carbon">carbon</a>-<a title="Carbon-based" href="http://en.wikipedia.org/wiki/Carbon-based">based</a> <a title="Biochemistry" href="http://en.wikipedia.org/wiki/Biochemistry">biochemistry</a>, carbon is the fundamental building block of the molecules that make up all known living things. Similarly <a title="Water" href="http://en.wikipedia.org/wiki/Water">water</a> is the basic <a title="Solvent" href="http://en.wikipedia.org/wiki/Solvent">solvent</a> for all known living organisms. While all these things are true of all organisms observed on Earth, in theory alternative forms of life could exist and some scientists do look at <a title="Alternative biochemistry" href="http://en.wikipedia.org/wiki/Alternative_biochemistry">alternative biochemistry</a>.</p><p>All terrestrial organisms use <a title="DNA" href="http://en.wikipedia.org/wiki/DNA">DNA</a> and <a title="RNA" href="http://en.wikipedia.org/wiki/RNA">RNA</a>-based <a title="Genetic material" href="http://en.wikipedia.org/wiki/Genetic_material">genetic mechanisms</a> to hold genetic information. Another universal principle is that all observed <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organisms</a> with the exception of <a title="Virus" href="http://en.wikipedia.org/wiki/Virus">viruses</a> are made of <a title="Cell (biology)" href="http://en.wikipedia.org/wiki/Cell_%28biology%29">cells</a>. Similarly, all organisms share common developmental processes.</p><p><a id="Homeostasis" name="Homeostasis"></a>&nbsp;</p> 

<dl><dd><div class="noprint"><em>Main article: <a title="Homeostasis" href="http://en.wikipedia.org/wiki/Homeostasis">Homeostasis</a></em></div></dd></dl><p>[[Homeostasis ]] is the ability of an <a title="Open system" href="http://en.wikipedia.org/wiki/Open_system">open system</a> to regulate its internal environment to maintain a stable condition by means of multiple <a title="Dynamic equilibrium" href="http://en.wikipedia.org/wiki/Dynamic_equilibrium">dynamic equilibrium</a> adjustments controlled by interrelated regulation mechanisms. All living <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organisms</a>, whether <a title="Unicellular" href="http://en.wikipedia.org/wiki/Unicellular">unicellular</a> or <a title="Multicellular" href="http://en.wikipedia.org/wiki/Multicellular">multicellular</a>, exhibit homeostasis. Homeostasis manifests itself at the cellular level through the maintenance of a stable internal acidity (<a title="PH" href="http://en.wikipedia.org/wiki/PH">pH</a>); at the organismic level, <a title="Warm-blooded" href="http://en.wikipedia.org/wiki/Warm-blooded">warm-blooded</a> animals maintain a constant internal body temperature; and at the level of the <a title="Ecosystem" href="http://en.wikipedia.org/wiki/Ecosystem">ecosystem</a>, as when atmospheric <a title="Carbon dioxide" href="http://en.wikipedia.org/wiki/Carbon_dioxide">carbon dioxide</a> levels rise and <a title="Plant" href="http://en.wikipedia.org/wiki/Plant">plants</a> are theoretically able to grow healthier and remove more of the gas from the atmosphere. <a title="Biological tissue" href="http://en.wikipedia.org/wiki/Biological_tissue">Tissues</a> and <a title="Organ (biology)" href="http://en.wikipedia.org/wiki/Organ_%28biology%29">organs</a> can also maintain homeostasis.</p>

<p><a id="Scope" name="Scope"></a>&nbsp;</p>

<dl><dd><div class="noprint"><em>Main article: <a title="List of biology disciplines" href="http://en.wikipedia.org/wiki/List_of_biology_disciplines">List of biology disciplines</a></em></div></dd></dl><p>Biology has become such a vast research enterprise that it is not generally regarded as a single discipline, but a number do assist in understanding the genetic variation of a population; and physiology borrows extensively from cell biology in describing the function of organ systems. <a title="Ethology" href="http://en.wikipedia.org/wiki/Ethology">Ethology</a> and <a title="Comparative psychology" href="http://en.wikipedia.org/wiki/Comparative_psychology">comparative psychology</a> extend biology to the analysis of animal behavior and mental characteristics, whilst <a title="Evolutionary psychology" href="http://en.wikipedia.org/wiki/Evolutionary_psychology">Evolutionary psychology</a> proposes that the field of psychology, including in regard to humans, is a branch of biology.<br clear="right" /></p><p><a id="Common_descent" name="Common_descent"></a></p>

<dl><dd><div class="noprint"><em>Main article: <a title="Universal common descent" href="http://en.wikipedia.org/wiki/Universal_common_descent">Universal common descent</a></em></div></dd></dl><p>Up into the <a title="19th century" href="http://en.wikipedia.org/wiki/19th_century">19th century</a>, it was believed that life forms were being continuously created under certain conditions (see <a title="Abiogenesis" href="http://en.wikipedia.org/wiki/Abiogenesis#Spontaneous_generation">spontaneous generation</a>). This misconception was challenged by <a title="William Harvey" href="http://en.wikipedia.org/wiki/William_Harvey">William Harvey</a>'s diction that &quot;all life [is] from [an] egg&quot; (from the <a title="Latin" href="http://en.wikipedia.org/wiki/Latin">Latin</a> &quot;<a title="Omne vivum ex ovo" href="http://en.wikipedia.org/wiki/Omne_vivum_ex_ovo">Omne vivum ex ovo</a>&quot;), a foundational concept of modern biology. It simply means that there is an unbroken continuity of life from its initial origin to the present time.</p><p>A group of organisms shares a common descent if they share a common <a title="Ancestor" href="http://en.wikipedia.org/wiki/Ancestor">ancestor</a>. All <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organisms</a> on the <a title="Earth" href="http://en.wikipedia.org/wiki/Earth">Earth</a> have been and are descended from a common ancestor or an ancestral <a title="Gene pool" href="http://en.wikipedia.org/wiki/Gene_pool">gene pool</a>. This last universal common ancestor of all organisms is believed to have appeared about <a title="Timeline of evolution" href="http://en.wikipedia.org/wiki/Timeline_of_evolution">3.5 billion years ago</a>. Biologists generally regard the universality of the <a title="Genetic code" href="http://en.wikipedia.org/wiki/Genetic_code">genetic code</a> as definitive evidence in favor of the theory of universal common descent (UCD) for all <a title="Bacterium" href="http://en.wikipedia.org/wiki/Bacterium">bacteria</a>, <a title="Archaea" href="http://en.wikipedia.org/wiki/Archaea">archaea</a>, and <a title="Eukaryote" href="http://en.wikipedia.org/wiki/Eukaryote">eukaryotes</a> (see: <a title="Origin of life" href="http://en.wikipedia.org/wiki/Origin_of_life">origin of life</a>).</p><p><a id="Structure_of_life" name="Structure_of_life"></a>&nbsp;</p>

<div class="thumbinner" style="widthWIDTH: 302px;" ><img class="thumbinnerthumbimage" height="182"><a titlealt="Schematic of typical animal cell depicting the various organelles and structures." classwidth="internal300" hreflongdesc="http://en.wikipedia.org/wiki/Image:Biological_cell.svg"><img width="300" height="182" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/1a/Biological_cell.svg/300px-Biological_cell.svg.png" class="thumbimage" longdesc="/wiki/Image:Biological_cell.svg" alt="Schematic of typical animal cell depicting the various organelles and structures." /></a>

<div style="float: right;" class="magnify"><a title="Enlarge" class="internal" hrefstyle="httpFLOAT://en.wikipedia.org/wiki/Image:Biological_cell.svgright"><img widthheight="1511" heightalt="11" altwidth="15" src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" /></a></div>Schematic of typical animal <a title="Cell (biology)" href="http://en.wikipedia.org/wiki/Cell_%28biology%29">cell</a> depicting the various <a title="Organelle" href="http://en.wikipedia.org/wiki/Organelle">organelles</a> and structures.</div>

</div><dl><dd><div class="noprint"><em>Main articles: <a title="Molecular biology" href="http://en.wikipedia.org/wiki/Molecular_biology">Molecular biology</a>, <a title="Cell biology" href="http://en.wikipedia.org/wiki/Cell_biology">Cell biology</a>, <a title="Genetics" href="http://en.wikipedia.org/wiki/Genetics">Genetics</a>, and <a title="Developmental biology" href="http://en.wikipedia.org/wiki/Developmental_biology">Developmental biology</a></em></div></dd></dl><p><a title="Molecular biology" href="http://en.wikipedia.org/wiki/Molecular_biology">Molecular biology</a> is the study of biology at a <a title="Molecular" href="http://en.wikipedia.org/wiki/Molecular">molecular</a> level. This field overlaps with other areas of biology, particularly with <a title="Genetics" href="http://en.wikipedia.org/wiki/Genetics">genetics</a> and <a title="Biochemistry" href="http://en.wikipedia.org/wiki/Biochemistry">biochemistry</a>. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interrelationship of DNA, RNA, and protein synthesis and learning how these interactions are regulated.</p><p><a title="Cell biology" href="http://en.wikipedia.org/wiki/Cell_biology">Cell biology</a> studies the <a title="Physiology" href="http://en.wikipedia.org/wiki/Physiology">physiological</a> properties of <a title="Cell (biology)" href="http://en.wikipedia.org/wiki/Cell_%28biology%29">cells</a>, as well as <strong>their <a title="Behavior" href="http://en.wikipedia.org/wiki/Behavior">behaviors</a>, interactions, and <a title="Natural environment" href="http://en.wikipedia.org/wiki/Natural_environment">environment</a>. This is done</strong> both on a <a title="Microscope" href="http://en.wikipedia.org/wiki/Microscope">microscopic</a> and <a title="Molecule" href="http://en.wikipedia.org/wiki/Molecule">molecular</a> level. Cell biology researches both single-celled organisms like <a title="Bacterium" href="http://en.wikipedia.org/wiki/Bacterium">bacteria</a> and specialized cells in multicellular organisms like <a title="Human" href="http://en.wikipedia.org/wiki/Human">humans</a>.</p>

<p><a title="Genetics" href="http://en.wikipedia.org/wiki/Genetics">Genetics</a> is the <a title="Science" href="http://en.wikipedia.org/wiki/Science">science</a> of <a title="Gene" href="http://en.wikipedia.org/wiki/Gene">genes</a>, <a title="Heredity" href="http://en.wikipedia.org/wiki/Heredity">heredity</a>, and the <a title="Variation" href="http://en.wikipedia.org/wiki/Variation">variation</a> of <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organisms</a>. <a title="Gene" href="http://en.wikipedia.org/wiki/Gene">Genes</a> encode the information necessary for synthesizing proteins, which in turn play a large role in influencing (though, in many instances, not completely determining) the final <a title="Phenotype" href="http://en.wikipedia.org/wiki/Phenotype">phenotype</a> of the organism. In modern research, genetics provides important tools in the investigation of the function of a particular gene, or the analysis of <a title="Genetic interaction" href="http://en.wikipedia.org/wiki/Genetic_interaction">genetic interactions</a>. Within <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organisms</a>, genetic information generally is carried in <a title="Chromosome" href="http://en.wikipedia.org/wiki/Chromosome">chromosomes</a>, where it is represented in the <a title="DNA sequence" href="http://en.wikipedia.org/wiki/DNA_sequence">chemical structure</a> of particular <a title="DNA" href="http://en.wikipedia.org/wiki/DNA">DNA</a> <a title="Molecule" href="http://en.wikipedia.org/wiki/Molecule">molecules</a>.</p><p>Developmental biology studies the process by which organisms grow and develop. Originating in <a title="Embryology" href="http://en.wikipedia.org/wiki/Embryology">embryology</a>, modern developmental biology studies the genetic control of <a title="Cell growth" href="http://en.wikipedia.org/wiki/Cell_growth">cell growth</a>, <a title="Cellular differentiation" href="http://en.wikipedia.org/wiki/Cellular_differentiation">differentiation</a>, and &quot;<a title="Morphogenesis" href="http://en.wikipedia.org/wiki/Morphogenesis">morphogenesis</a>,&quot; which is the process that gives rise to <a title="Biological tissue" href="http://en.wikipedia.org/wiki/Biological_tissue">tissues</a>, <a title="Organ (anatomy)" href="http://en.wikipedia.org/wiki/Organ_%28anatomy%29">organs</a>, and <a title="Anatomy" href="http://en.wikipedia.org/wiki/Anatomy">anatomy</a>. <a title="Model organism" href="http://en.wikipedia.org/wiki/Model_organism">Model organisms</a> for developmental biology include the round worm <em><a title="Caenorhabditis elegans" href="http://en.wikipedia.org/wiki/Caenorhabditis_elegans">Caenorhabditis elegans</a></em>, the fruit fly <em><a title="Drosophila melanogaster" href="http://en.wikipedia.org/wiki/Drosophila_melanogaster">Drosophila melanogaster</a></em>, the zebrafish <em><a title="Brachydanio rerio" href="http://en.wikipedia.org/wiki/Brachydanio_rerio">Brachydanio rerio</a></em>, the mouse <em><a title="Mus musculus" href="http://en.wikipedia.org/wiki/Mus_musculus">Mus musculus</a></em>, and the weed <em><a title="Arabidopsis thaliana" href="http://en.wikipedia.org/wiki/Arabidopsis_thaliana">Arabidopsis thaliana</a></em>.</p><p><a id="Physiology_of_organisms" name="Physiology_of_organisms"></a>&nbsp;</p>

<p><em>Main articles:</em> <strong><a title="Physiology" href="http://en.wikipedia.org/wiki/Physiology">Physiology</a></strong>, <a title="Anatomy" href="http://en.wikipedia.org/wiki/Anatomy">Anatomy</a></p><p>Physiology studies the mechanical, physical, and biochemical processes of living organisms by attempting to understand how all of the structures function as a whole. The theme of &quot;structure to function&quot; is central to biology. Physiological studies have traditionally been divided into <a title="Plant physiology" href="http://en.wikipedia.org/wiki/Plant_physiology">plant physiology</a> and <a title="Animal physiology" href="http://en.wikipedia.org/wiki/Animal_physiology">animal physiology</a>, but the principles of physiology are universal, no matter what particular <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organism</a> is being studied. For example, what is learned about the physiology of <a title="Yeast" href="http://en.wikipedia.org/wiki/Yeast">yeast</a> cells can also apply to <a title="Human" href="http://en.wikipedia.org/wiki/Human">human</a> cells. The field of animal physiology extends the tools and methods of <a title="Human physiology" href="http://en.wikipedia.org/wiki/Human_physiology">human physiology</a> to non-human <a title="Species" href="http://en.wikipedia.org/wiki/Species">species</a>. Plant physiology also borrows techniques from both fields.</p><p><a title="Anatomy" href="http://en.wikipedia.org/wiki/Anatomy">Anatomy</a> is an important branch of physiology and considers how <a title="Organ (biology)" href="http://en.wikipedia.org/wiki/Organ_%28biology%29">organ</a> systems in animals, such as the <a title="Nervous system" href="http://en.wikipedia.org/wiki/Nervous_system">nervous</a>, <a title="Immune system" href="http://en.wikipedia.org/wiki/Immune_system">immune</a>, <a title="Endocrine system" href="http://en.wikipedia.org/wiki/Endocrine_system">endocrine</a>, <a title="Respiratory system" href="http://en.wikipedia.org/wiki/Respiratory_system">respiratory</a>, and <a title="Circulatory system" href="http://en.wikipedia.org/wiki/Circulatory_system">circulatory</a> systems, function and interact. The study of these systems is shared with <a title="Medicine" href="http://en.wikipedia.org/wiki/Medicine">medically</a> oriented disciplines such as <a title="Neurology" href="http://en.wikipedia.org/wiki/Neurology">neurology</a> and <a title="Immunology" href="http://en.wikipedia.org/wiki/Immunology">immunology</a>.</p><p><a id="Diversity_and_evolution_of_organisms" name="Diversity_and_evolution_of_organisms"></a>&nbsp;</p>

<div class="thumbinner" style="widthWIDTH: 302px;" ><img class="thumbinnerthumbimage" height="148"><a titlealt="In population genetics the evolution of a population of organisms is sometimes depicted as if travelling on a fitness landscape. The arrows indicate the preferred flow of a population on the landscape, and the points A, B, and C are local optima. The red ball indicates a population that moves from a very low fitness value to the top of a peak." classwidth="internal300" hreflongdesc="http://en.wikipedia.org/wiki/Image:Fitness-landscape-cartoon.png"><img width="300" height="148" src="http://upload.wikimedia.org/wikipedia/commons/thumb/6/67/Fitness-landscape-cartoon.png/300px-Fitness-landscape-cartoon.png" class="thumbimage" longdesc="/wiki/Image:Fitness-landscape-cartoon.png" alt="In population genetics the evolution of a population of organisms is sometimes depicted as if travelling on a fitness landscape. The arrows indicate the preferred flow of a population on the landscape, and the points A, B, and C are local optima. The red ball indicates a population that moves from a very low fitness value to the top of a peak." /></a>

<div style="float: right;" class="magnify"><a titlestyle="Enlarge" class="internal" href="httpFLOAT://en.wikipedia.org/wiki/Image:Fitness-landscape-cartoon.pngright"><img widthheight="1511" heightalt="11" altwidth="15" src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" /></a></div>In <a title="Population genetics" href="http://en.wikipedia.org/wiki/Population_genetics">population genetics</a> the <a title="Evolution" href="http://en.wikipedia.org/wiki/Evolution">evolution</a> of a <a title="Population" href="http://en.wikipedia.org/wiki/Population">population</a> of organisms is sometimes depicted as if travelling on a <a title="Fitness landscape" href="http://en.wikipedia.org/wiki/Fitness_landscape">fitness landscape</a>. The arrows indicate the preferred flow of a population on the landscape, and the points A, B, and C are local optima. The red ball indicates a population that moves from a very low fitness value to the top of a peak.</div>

<p><em>Main articles:</em> <strong><a title="Evolutionary biology" href="http://en.wikipedia.org/wiki/Evolutionary_biology">Evolutionary biology</a></strong>, <a title="Biodiversity" href="http://en.wikipedia.org/wiki/Biodiversity">Biodiversity</a>, <a title="Botany" href="http://en.wikipedia.org/wiki/Botany">Botany</a>, <a title="Zoology" href="http://en.wikipedia.org/wiki/Zoology">Zoology</a> is concerned with the origin and descent of <a title="Species" href="http://en.wikipedia.org/wiki/Species">species</a>, as well as their change over time, and includes scientists from many <a title="Alpha taxonomy" href="http://en.wikipedia.org/wiki/Alpha_taxonomy">taxonomically</a>-oriented disciplines. For example, it generally involves scientists who have special training in particular <a title="Organism" href="http://en.wikipedia.org/wiki/Organism">organisms</a> such as <a title="Mammals" href="http://en.wikipedia.org/wiki/Mammals">mammalogy</a>, <a title="Birds" href="http://en.wikipedia.org/wiki/Birds">ornithology</a>, or <a title="Reptiles" href="http://en.wikipedia.org/wiki/Reptiles">herpetology</a>, but use those organisms as systems to answer general questions about evolution. Evolutionary biology is mainly based on <a title="Paleontology" href="http://en.wikipedia.org/wiki/Paleontology">paleontology</a>, which uses the <a title="Fossil" href="http://en.wikipedia.org/wiki/Fossil">fossil</a> record to answer questions about the mode and tempo of evolution, as well as the developments in areas such as <a title="Population genetics" href="http://en.wikipedia.org/wiki/Population_genetics">population genetics</a> and evolutionary theory. In the <a title="1990s" href="http://en.wikipedia.org/wiki/1990s">1990s</a>, <a title="Developmental biology" href="http://en.wikipedia.org/wiki/Developmental_biology">developmental biology</a> re-entered evolutionary biology from its initial exclusion from the modern synthesis through the study of <a title="Evolutionary developmental biology" href="http://en.wikipedia.org/wiki/Evolutionary_developmental_biology">evolutionary developmental biology</a>. Related fields which are often considered part of evolutionary biology are <a title="Phylogenetics" href="http://en.wikipedia.org/wiki/Phylogenetics">phylogenetics</a>, <a title="Systematics" href="http://en.wikipedia.org/wiki/Systematics">systematics</a>, and <a title="Alpha taxonomy" href="http://en.wikipedia.org/wiki/Alpha_taxonomy">taxonomy</a>.</p><p>The two major traditional taxonomically-oriented disciplines are <a title="Botany" href="http://en.wikipedia.org/wiki/Botany">botany</a> and <a title="Zoology" href="http://en.wikipedia.org/wiki/Zoology">zoology</a>. Botany is the scientific study of <a title="Plant" href="http://en.wikipedia.org/wiki/Plant">plants</a>. Botany covers a wide range of scientific disciplines that study the <a title="Growth" href="http://en.wikipedia.org/wiki/Growth">growth</a>, <a title="Reproduction" href="http://en.wikipedia.org/wiki/Reproduction">reproduction</a>, <a title="Metabolism" href="http://en.wikipedia.org/wiki/Metabolism">metabolism</a>, <a title="Morphogenesis" href="http://en.wikipedia.org/wiki/Morphogenesis">development</a>, <a title="Phytopathology" href="http://en.wikipedia.org/wiki/Phytopathology">diseases</a>, and <a title="Evolution" href="http://en.wikipedia.org/wiki/Evolution">evolution</a> of plant life. Zoology involves the study of <a title="Animal" href="http://en.wikipedia.org/wiki/Animal">animals</a>, including the study of their <a title="Physiology" href="http://en.wikipedia.org/wiki/Physiology">physiology</a> within the fields of <a title="Anatomy" href="http://en.wikipedia.org/wiki/Anatomy">anatomy</a> and <a title="Embryology" href="http://en.wikipedia.org/wiki/Embryology">embryology</a>. The common <a title="Genetics" href="http://en.wikipedia.org/wiki/Genetics">genetic</a> and developmental mechanisms of animals and plants is studied in <a title="Molecular biology" href="http://en.wikipedia.org/wiki/Molecular_biology">molecular biology</a>, <a title="Molecular genetics" href="http://en.wikipedia.org/wiki/Molecular_genetics">molecular genetics</a>, and <a title="Developmental biology" href="http://en.wikipedia.org/wiki/Developmental_biology">developmental biology</a>. The <a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">ecology</a> of animals is covered under <a title="Behavioral ecology" href="http://en.wikipedia.org/wiki/Behavioral_ecology">behavioral ecology</a> and other fields.</p><p><a id="Taxonomy" name="Taxonomy"></a>&nbsp;</p>

<div class="messagebox cleanup metadata plainlinks"><strong>This article or section does not cite any <a title="Wikipedia:Citing sources" href="http://en.wikipedia.org/wiki/Wikipedia:Citing_sources">references or sources</a>.</strong><br /><small>Please help <a rel="nofollow" title="http://en.wikipedia.org/w/index.php?title=Biology&amp;action=edit" class="external text" href="http://en.wikipedia.org/w/index.php?title=Biology&amp;action=edit">improve this article</a> by adding citations to <a title="Wikipedia:Verifiability" href="http://en.wikipedia.org/wiki/Wikipedia:Verifiability">reliable sources</a>. (<a title="Help:Contents" href="http://en.wikipedia.org/wiki/Help:Contents">help</a>, <a title="Wikipedia:WikiProject Fact and Reference Check" href="http://en.wikipedia.org/wiki/Wikipedia:WikiProject_Fact_and_Reference_Check">get involved!</a>)<br />

<div class="thumbinner" style="widthWIDTH: 342px;" ><img class="thumbinnerthumbimage" height="230"><a titlealt="A phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains bacteria, archaea, and eukaryotes as described initially by Carl Woese. Trees constructed with other genes are generally similar, although they may place some early-branching groups very differently, presumably owing to rapid rRNA evolution. The exact relationships of the three domains are still being debated." classwidth="internal340" hreflongdesc="http://en.wikipedia.org/wiki/Image:Phylogenetic_tree.svg"><img width="340" height="230" src="http://upload.wikimedia.org/wikipedia/commons/thumb/7/70/Phylogenetic_tree.svg/340px-Phylogenetic_tree.svg.png" class="thumbimage" longdesc="/wiki/Image:Phylogenetic_tree.svg" alt="A phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains bacteria, archaea, and eukaryotes as described initially by Carl Woese. Trees constructed with other genes are generally similar, although they may place some early-branching groups very differently, presumably owing to rapid rRNA evolution. The exact relationships of the three domains are still being debated." /></a>

<div style="float: right;" class="magnify"><a title="Enlarge" class="internal" hrefstyle="httpFLOAT://en.wikipedia.org/wiki/Image:Phylogenetic_tree.svgright"><img widthheight="1511" heightalt="11" altwidth="15" src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" /></a></div>A <a title="Phylogenetic tree" href="http://en.wikipedia.org/wiki/Phylogenetic_tree">phylogenetic tree</a> of <a title="Evolutionary tree" href="http://en.wikipedia.org/wiki/Evolutionary_tree">all living things</a>, based on <a title="RRNA" href="http://en.wikipedia.org/wiki/RRNA">rRNA</a> <a title="Gene" href="http://en.wikipedia.org/wiki/Gene">gene</a> data, showing the separation of the three domains <a title="Bacterium" href="http://en.wikipedia.org/wiki/Bacterium">bacteria</a>, <a title="Archaea" href="http://en.wikipedia.org/wiki/Archaea">archaea</a>, and <a title="Eukaryote" href="http://en.wikipedia.org/wiki/Eukaryote">eukaryotes</a> as described initially by <a title="Carl Woese" href="http://en.wikipedia.org/wiki/Carl_Woese">Carl Woese</a>. Trees constructed with other genes are generally similar, although they may place some early-branching groups very differently, presumably owing to rapid rRNA evolution. The exact relationships of the three domains are still being debated.</div>

<p>Classification is the province of the disciplines of <a title="Systematics" href="http://en.wikipedia.org/wiki/Systematics">systematics</a> and <a title="Alpha taxonomy" href="http://en.wikipedia.org/wiki/Alpha_taxonomy">taxonomy</a>. Taxonomy places organisms in groups called <a title="Taxa" href="http://en.wikipedia.org/wiki/Taxa">taxa</a>, while systematics seeks to define their relationships with each other. This classification technique has evolved to reflect advances in <a title="Cladistics" href="http://en.wikipedia.org/wiki/Cladistics">cladistics</a> and <a title="Genetics" href="http://en.wikipedia.org/wiki/Genetics">genetics</a>, shifting the focus from physical similarities and shared characteristics to <a title="Phylogenetics" href="http://en.wikipedia.org/wiki/Phylogenetics">phylogenetics</a>.</p>

<dl><dd><a title="Monera" href="http://en.wikipedia.org/wiki/Monera">Monera</a> -- <a title="Protist" href="http://en.wikipedia.org/wiki/Protist">Protista</a> -- <a title="Fungus" href="http://en.wikipedia.org/wiki/Fungus">Fungi</a> -- <a title="Plant" href="http://en.wikipedia.org/wiki/Plant">Plantae</a> -- <a title="Animal" href="http://en.wikipedia.org/wiki/Animal">Animalia</a></dd></dl><p>However, many scientists now consider this five-kingdom system to be outdated. Modern alternative classification systems generally begin with the <a title="Three-domain system" href="http://en.wikipedia.org/wiki/Three-domain_system">three-domain system</a>:<sup class="reference" id="_ref-2"><a title="" href="http://en.wikipedia.org/wiki/Biology#_note-2">[3]</a></sup></p><dl><dd><a title="Archaea" href="http://en.wikipedia.org/wiki/Archaea">Archaea</a> (originally Archaebacteria) -- <a title="Bacterium" href="http://en.wikipedia.org/wiki/Bacterium">Bacteria</a> (originally Eubacteria) -- <a title="Eukaryote" href="http://en.wikipedia.org/wiki/Eukaryote">Eukaryota</a></dd></dl>

<li><a title="Kingdom (biology)" href="http://en.wikipedia.org/wiki/Kingdom_%28biology%29">Kingdom</a></li> <li><a title="Phylum" href="http://en.wikipedia.org/wiki/Phylum">Phylum</a></li> <li><a title="Class (biology)" href="http://en.wikipedia.org/wiki/Class_%28biology%29">Class</a></li> <li><a title="Order (biology)" href="http://en.wikipedia.org/wiki/Order_%28biology%29">Order</a></li> <li><a title="Family (biology)" href="http://en.wikipedia.org/wiki/Family_%28biology%29">Family</a></li> <li><a title="Genus" href="http://en.wikipedia.org/wiki/Genus">Genus</a></li> <li><a title="Species" href="http://en.wikipedia.org/wiki/Species">Species</a></li>

<p>The scientific name of an organism is obtained from its genus and species. For example, humans would be listed as <em><a title="Homo sapiens" href="http://en.wikipedia.org/wiki/Homo_sapiens">Homo sapiens</a></em>. <em>Homo</em> would be the genus and <em>sapiens</em> is the species. Whenever writing the scientific name of an organism, it is proper to capitalize the first letter in the genus and put all of the species in lowercase; in addition the entire term would be put in italics or underlined. The term used for classification is called <a title="Taxonomy" href="http://en.wikipedia.org/wiki/Taxonomy">taxonomy</a>.</p><p>There is also a series of intracellular <a title="Parasite" href="http://en.wikipedia.org/wiki/Parasite">parasites</a> that are progressively &quot;less alive&quot; in terms of <a title="Metabolism" href="http://en.wikipedia.org/wiki/Metabolism">metabolic</a> activity:</p><dl><dd><a title="Virus (biology)" href="http://en.wikipedia.org/wiki/Virus_%28biology%29">Viruses</a> -- <a title="Viroid" href="http://en.wikipedia.org/wiki/Viroid">Viroids</a> -- <a title="Prion" href="http://en.wikipedia.org/wiki/Prion">Prions</a></dd></dl>

The dominant classification system is called <a title="Linnaean taxonomy" href="http://en.wikipedia.org/wiki/Linnaean_taxonomy">Linnaean taxonomy</a>, which includes ranks and <a title="Binomial nomenclature" href="http://en.wikipedia.org/wiki/Binomial_nomenclature">binomial nomenclature</a>. How organisms are named is governed by international agreements such as the <a title="International Code of Botanical Nomenclature" href="http://en.wikipedia.org/wiki/International_Code_of_Botanical_Nomenclature">International Code of Botanical Nomenclature</a> (ICBN), the <a title="International Code of Zoological Nomenclature" href="http://en.wikipedia.org/wiki/International_Code_of_Zoological_Nomenclature">International Code of Zoological Nomenclature</a> (ICZN), and the <a title="International Code of Nomenclature of Bacteria" href="http://en.wikipedia.org/wiki/International_Code_of_Nomenclature_of_Bacteria">International Code of Nomenclature of Bacteria</a> (ICNB). A fourth Draft BioCode was published in 1997 in an attempt to standardize naming in these three areas, but it has yet to be formally adopted. The <a title="Virus classification" href="http://en.wikipedia.org/wiki/Virus_classification">Virus cInternational Code of Virus Classification and Nomenclature</a> (ICVCN) remains outside the BioCode.</p><p><a id="Interactions_of_organisms" name="Interactions_of_organisms"></a>&nbsp;</p>

<dl><dd><div class="noprint"><em>Main articles: <a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">Ecology</a>, <a title="Ethology" href="http://en.wikipedia.org/wiki/Ethology">Ethology</a>, <a title="Behavior" href="http://en.wikipedia.org/wiki/Behavior">Behavior</a>, and <a title="Biogeography" href="http://en.wikipedia.org/wiki/Biogeography">Biogeography</a></em></div></dd></dl><p><a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">Ecology</a> studies the distribution and abundance of <a title="Life" href="http://en.wikipedia.org/wiki/Life">living organisms</a>, and the interactions between organisms and their <a title="Natural environment" href="http://en.wikipedia.org/wiki/Natural_environment">environment</a>. The environment of an organism includes both its habitat, which can be described as the sum of local abiotic factors such as <a title="Climate" href="http://en.wikipedia.org/wiki/Climate">climate</a> and <a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">ecology</a>, as well as the other the organisms that share its habitat. Ecological systems are studied at several different levels, from individuals and <a title="Population" href="http://en.wikipedia.org/wiki/Population">populations</a> to <a title="Ecosystem" href="http://en.wikipedia.org/wiki/Ecosystem">ecosystems</a> and the <a title="Biosphere" href="http://en.wikipedia.org/wiki/Biosphere">biosphere</a>. As can be surmised, ecology is a science that draws on several disciplines.</p><p><a title="Ethology" href="http://en.wikipedia.org/wiki/Ethology">Ethology</a> studies <a title="Animal" href="http://en.wikipedia.org/wiki/Animal">animal</a> <a title="Behavior" href="http://en.wikipedia.org/wiki/Behavior">behavior</a> (particularly of social animals such as <a title="Primate" href="http://en.wikipedia.org/wiki/Primate">primates</a> and <a title="Canidae" href="http://en.wikipedia.org/wiki/Canidae">canids</a>), and is sometimes considered a branch of <a title="Zoology" href="http://en.wikipedia.org/wiki/Zoology">zoology</a>. Ethologists have been particularly concerned with the <a title="Evolution" href="http://en.wikipedia.org/wiki/Evolution">evolution</a> of behavior and the understanding of behavior in terms of the theory of <a title="Natural selection" href="http://en.wikipedia.org/wiki/Natural_selection">natural selection</a>. In one sense, the first modern ethologist was <a title="Charles Darwin" href="http://en.wikipedia.org/wiki/Charles_Darwin">Charles Darwin</a>, whose book &quot;<a title="The Expression of the Emotions in Man and Animals" href="http://en.wikipedia.org/wiki/The_Expression_of_the_Emotions_in_Man_and_Animals">The Expression of the Emotions in Man and Animals</a>&quot; influenced many ethologists.</p><p><a title="Biogeography" href="http://en.wikipedia.org/wiki/Biogeography">Biogeography</a> studies the spatial distribution of organisms on the <a title="Earth" href="http://en.wikipedia.org/wiki/Earth">Earth</a>, focusing on topics like <a title="Plate tectonics" href="http://en.wikipedia.org/wiki/Plate_tectonics">plate tectonics</a>, <a title="Climate change" href="http://en.wikipedia.org/wiki/Climate_change">climate change</a>, dispersal and migration, and <a title="Cladistics" href="http://en.wikipedia.org/wiki/Cladistics">cladistics</a>.</p><p>Every living thing interacts with other organisms and its <a title="Natural environment" href="http://en.wikipedia.org/wiki/Natural_environment">environment</a>. One reason that biological systems can be difficult to study is that so many different interactions with other organisms and the environment are possible, even on the smallest of scales. A microscopic <a title="Bacterium" href="http://en.wikipedia.org/wiki/Bacterium">bacterium</a> responding to a local sugar gradient is responding to its environment as much as a <a title="Lion" href="http://en.wikipedia.org/wiki/Lion">lion</a> is responding to its environment when it searches for food in the <a title="Africa" href="http://en.wikipedia.org/wiki/Africa">African</a> <a title="Savanna" href="http://en.wikipedia.org/wiki/Savanna">savannah</a>. For any given species, <a title="Behavior" href="http://en.wikipedia.org/wiki/Behavior">behaviors</a> can be <a title="Co-operation" href="http://en.wikipedia.org/wiki/Co-operation">co-operative</a>, <a title="Aggression" href="http://en.wikipedia.org/wiki/Aggression">aggressive</a>, <a title="Parasite" href="http://en.wikipedia.org/wiki/Parasite">parasitic</a> or <a title="Symbiosis" href="http://en.wikipedia.org/wiki/Symbiosis">symbiotic</a>. Matters become more complex when two or more different species interact in an <a title="Ecosystem" href="http://en.wikipedia.org/wiki/Ecosystem">ecosystem</a>. Studies of this type are the province of <a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">ecology</a>.</p>

<p><a id="History" name="History"></a>&nbsp;</p>

<dl><dd><div class="noprint"><em>Main articles: <a title="History of biology" href="http://en.wikipedia.org/wiki/History_of_biology">History of biology</a> and <a title="History of medicine" href="http://en.wikipedia.org/wiki/History_of_medicine">History of medicine</a></em></div></dd></dl><p>Although the concept of <em><strong class="selflink">biology</strong></em> as a single coherent field arose in the 19th century, the biological sciences emerged from <a title="History of medicine" href="http://en.wikipedia.org/wiki/History_of_medicine">traditions of medicine</a> and <a title="Natural history" href="http://en.wikipedia.org/wiki/Natural_history">natural history</a> reaching back to <a title="Galen" href="http://en.wikipedia.org/wiki/Galen">Galen</a> and <a title="Aristotle" href="http://en.wikipedia.org/wiki/Aristotle">Aristotle</a> in ancient Greece. During the Renaissance and early modern period, biological thought was revolutionized by a renewed interest in <a title="Empiricism" href="http://en.wikipedia.org/wiki/Empiricism">empiricism</a> and the discovery of many novel organisms. Prominent in this movement were <a title="Vesalius" href="http://en.wikipedia.org/wiki/Vesalius">Vesalius</a> and <a title="William Harvey" href="http://en.wikipedia.org/wiki/William_Harvey">Harvey</a>, who used experimentation and careful observation in physiology, and naturalists such as <a title="Carolus Linnaeus" href="http://en.wikipedia.org/wiki/Carolus_Linnaeus">Linnaeus</a> and <a title="Georges-Louis Leclerc, Comte de Buffon" href="http://en.wikipedia.org/wiki/Georges-Louis_Leclerc%2C_Comte_de_Buffon">Buffon</a> who began to <a title="Scientific classification" href="http://en.wikipedia.org/wiki/Scientific_classification">classify the diversity of life</a> and the <a title="Fossil record" href="http://en.wikipedia.org/wiki/Fossil_record">fossil record</a>, as well as the development and behavior of organisms. <a title="Microscopy" href="http://en.wikipedia.org/wiki/Microscopy">Microscopy</a> revealed the previously unknown world of microorganisms, laying the groundwork for <a title="Cell theory" href="http://en.wikipedia.org/wiki/Cell_theory">cell theory</a>. The growing importance of <a title="Natural theology" href="http://en.wikipedia.org/wiki/Natural_theology">natural theology</a>, partly a response to the rise of <a title="Mechanical philosophy" href="http://en.wikipedia.org/wiki/Mechanical_philosophy">mechanical philosophy</a>, encouraged the growth of natural history (though it entrenched the <a title="Argument from design" href="http://en.wikipedia.org/wiki/Argument_from_design">argument from design</a>).<sup class="reference" id="_ref-3"><a title="" href="http://en.wikipedia.org/wiki/Biology#_note-3">[4]</a></sup></p><p>Over the 18th and 19th centuries, biological sciences such as <a title="Botany" href="http://en.wikipedia.org/wiki/Botany">botany</a> and <a title="Zoology" href="http://en.wikipedia.org/wiki/Zoology">zoology</a> became increasingly professional <a title="Scientific discipline" href="http://en.wikipedia.org/wiki/Scientific_discipline">scientific disciplines</a>. <a title="Lavoisier" href="http://en.wikipedia.org/wiki/Lavoisier">Lavoisier</a> and other physical scientists began to connect the animate and inanimate worlds through physics and chemistry. Explorer-naturalists such as <a title="Alexander von Humboldt" href="http://en.wikipedia.org/wiki/Alexander_von_Humboldt">Alexander von Humboldt</a> investigated the interaction between organisms and their environment, and the ways this relationship depends on geography&mdash;laying the foundations for <a title="Biogeography" href="http://en.wikipedia.org/wiki/Biogeography">biogeography</a>, <a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">ecology</a> and <a title="Ethology" href="http://en.wikipedia.org/wiki/Ethology">ethology</a>. Naturalists began to reject <a title="Essentialism" href="http://en.wikipedia.org/wiki/Essentialism">essentialism</a> and consider the importance of <a title="Extinction" href="http://en.wikipedia.org/wiki/Extinction">extinction</a> and the <a title="History of evolutionary thought" href="http://en.wikipedia.org/wiki/History_of_evolutionary_thought">mutability of species</a>. <a title="Cell theory" href="http://en.wikipedia.org/wiki/Cell_theory">Cell theory</a> provided a new perspective on the fundamental basis of life. These developments, as well as the results from <a title="Embryology" href="http://en.wikipedia.org/wiki/Embryology">embryology</a> and <a title="Paleontology" href="http://en.wikipedia.org/wiki/Paleontology">paleontology</a>, were synthesized in <a title="Charles Darwin" href="http://en.wikipedia.org/wiki/Charles_Darwin">Charles Darwin's</a> theory of <a title="Evolution" href="http://en.wikipedia.org/wiki/Evolution">evolution</a> by <a title="Natural selection" href="http://en.wikipedia.org/wiki/Natural_selection">natural selection</a>. The end of the 19th century saw the fall of <a title="Spontaneous generation" href="http://en.wikipedia.org/wiki/Spontaneous_generation">spontaneous generation</a> and the rise of the <a title="Germ theory of disease" href="http://en.wikipedia.org/wiki/Germ_theory_of_disease">germ theory of disease</a>, though the mechanism of <a title="Biological inheritance" href="http://en.wikipedia.org/wiki/Biological_inheritance">inheritance</a> remained a mystery.<sup class="reference" id="_ref-4"><a title="" href="http://en.wikipedia.org/wiki/Biology#_note-4">[5]</a></sup></p><p>In the early 20th century, the rediscovery of <a title="Gregor Mendel" href="http://en.wikipedia.org/wiki/Gregor_Mendel">Mendel's</a> work led to the rapid development of <a title="Genetics" href="http://en.wikipedia.org/wiki/Genetics">genetics</a> by <a title="Thomas Hunt Morgan" href="http://en.wikipedia.org/wiki/Thomas_Hunt_Morgan">Thomas Hunt Morgan</a> and his students, and by the 1930s the combination of <a title="Population genetics" href="http://en.wikipedia.org/wiki/Population_genetics">population genetics</a> and natural selection in the &quot;<a title="Modern evolutionary synthesis" href="http://en.wikipedia.org/wiki/Modern_evolutionary_synthesis">neo-Darwinian synthesis</a>&quot;. New disciplines developed rapidly, especially after <a title="James D. Watson" href="http://en.wikipedia.org/wiki/James_D._Watson">Watson</a> and <a title="Francis Crick" href="http://en.wikipedia.org/wiki/Francis_Crick">Crick</a> proposed the structure of <a title="DNA" href="http://en.wikipedia.org/wiki/DNA">DNA</a>. Following the establishment of the <a title="Central Dogma" href="http://en.wikipedia.org/wiki/Central_Dogma">Central Dogma</a> and the cracking of the <a title="Genetic code" href="http://en.wikipedia.org/wiki/Genetic_code">genetic code</a>, biology was largely split between <em>organismal biology</em>&mdash;the fields that deal with whole organisms and groups of organisms&mdash;and the fields related to <em><a title="Cell biology" href="http://en.wikipedia.org/wiki/Cell_biology">cellular</a> and <a title="Molecular biology" href="http://en.wikipedia.org/wiki/Molecular_biology">molecular biology</a></em>. By the late 20th century, new fields like <a title="Genomics" href="http://en.wikipedia.org/wiki/Genomics">genomics</a> and <a title="Proteomics" href="http://en.wikipedia.org/wiki/Proteomics">proteomics</a> were reversing this trend, with organismal biologists using molecular techniques, and molecular and cell biologists investigating the interplay between genes and the environment, as well as the genetics of natural populations of organisms.<sup class="reference" id="_ref-5"><a title="" href="http://en.wikipedia.org/wiki/Biology#_note-5">[6]</a></sup></p><p><a id="See_also" name="See_also"></a>&nbsp;</p>

<dl><ddp><em>Main lists: <a title="List of biology topics" href="http://en.wikipedia.org/wiki/List_of_biology_topics"em>List of biology topics</ap>, <a titletable id="List of basic biology topics" href="http://en.wikipedia.org/wiki/List_of_basic_biology_topics">List of basic biology topics</a> and <a title="List of biologists" href="http://en.wikipedia.org/wiki/List_of_biologiststoc">List of biologists</a></em></dd></dl><table width="100%" bgcolor="#fff4f4" id="toc">

<th align="center" colspan="2"><a title="List of biology topics" href="http://en.wikipedia.org/wiki/List_of_biology_topics">Topics related to biology</a> (<a title="Category:Biology" href="http://en.wikipedia.org/wiki/Category:Biology">Category</a>)</th>

<td valign="top" align="left"><a title="Biologist" href="http://en.wikipedia.org/wiki/Biologist">Biologist</a> - <a title="List of biologists" href="http://en.wikipedia.org/wiki/List_of_biologists">Notable biologists</a> - <a title="History of biology" href="http://en.wikipedia.org/wiki/History_of_biology">History of biology</a> - <a title="Nobel Prize in Physiology or Medicine" href="http://en.wikipedia.org/wiki/Nobel_Prize_in_Physiology_or_Medicine">Nobel Prize in Physiology or Medicine</a> - <a title="Timeline of biology and organic chemistry" href="http://en.wikipedia.org/wiki/Timeline_of_biology_and_organic_chemistry">Timeline of biology and organic chemistry</a> - <a title="List of geneticists and biochemists" href="http://en.wikipedia.org/wiki/List_of_geneticists_and_biochemists">List of geneticists and biochemists</a></td>

<td valign="top" align="left"><a title="NASA Ames Research Center" href="http://en.wikipedia.org/wiki/NASA_Ames_Research_Center">NASA Ames Research Center</a> - <a title="Bachelor of Science" href="http://en.wikipedia.org/wiki/Bachelor_of_Science">Bachelor of Science</a> - <a title="List of publications in biology" href="http://en.wikipedia.org/wiki/List_of_publications_in_biology">Publications</a></td>

<td valign="top" align="left"><em><a title="Omne vivum ex ovo" href="http://en.wikipedia.org/wiki/Omne_vivum_ex_ovo">Omne vivum ex ovo</a></em> - <em><a title="In vivo" href="http://en.wikipedia.org/wiki/In_vivo">In vivo</a></em> - <em><a title="In vitro" href="http://en.wikipedia.org/wiki/In_vitro">In vitro</a></em> - <em><a title="In utero" href="http://en.wikipedia.org/wiki/In_utero">In utero</a></em> - <em><a title="In silico" href="http://en.wikipedia.org/wiki/In_silico">In silico</a></em></td>

<td valign="top" align="left"><a title="Medicine" href="http://en.wikipedia.org/wiki/Medicine">Medicine</a> (<a title="Physician" href="http://en.wikipedia.org/wiki/Physician">Physician</a>) - <a title="Physical anthropology" href="http://en.wikipedia.org/wiki/Physical_anthropology">Physical anthropology</a> - <a title="Environmental science" href="http://en.wikipedia.org/wiki/Environmental_science">Environmental science</a> - <a title="Life Sciences" href="http://en.wikipedia.org/wiki/Life_Sciences">Life Sciences</a> - <a title="Biotechnology" href="http://en.wikipedia.org/wiki/Biotechnology">Biotechnology</a></td>

<td valign="top" align="left"><a title="List of conservation topics" href="http://en.wikipedia.org/wiki/List_of_conservation_topics">List of conservation topics</a></td>

<p><a id="References" name="References"></a>&nbsp;</p>

<div class="references-small" style="-moz-column-count: 2;" class="references-small">

<li id="_note-0"><strong><a title="" href="http://en.wikipedia.org/wiki/Biology#_ref-0">^</a></strong> <em>Biology: A Functional Approach</em> By Michael Bliss Vaughan Roberts. Cheltenham: Thomas Nelson and Sons, 1986. pg. 1</li> <li id="_note-1"><strong><a title="" href="http://en.wikipedia.org/wiki/Biology#_ref-1">^</a></strong> Dawkins, R. (1976) The Selfish Gene. Oxford University Press. Second edition (1989)</li> <li id="_note-2"><strong><a title="" href="http://en.wikipedia.org/wiki/Biology#_ref-2">^</a></strong> <cite style="fontFONT-styleSTYLE: normal;">Woese C, Kandler O, Wheelis M (1990). &quot;<a rel="nofollow" title="http://www.pnas.org/cgi/reprint/87/12/4576" class="external text" href="http://www.pnas.org/cgi/reprint/87/12/4576">Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya.</a>&quot;. <em>Proc Natl Acad Sci U S A</em> <strong>87</strong> (12): 4576-9. <a title="International Standard Serial Number" href="http://en.wikipedia.org/wiki/International_Standard_Serial_Number">ISSN</a> <a rel="nofollow" title="http://worldcat.org/issn/0027-8424" class="external text" href="http://worldcat.org/issn/0027-8424">0027-8424</a>. <a title="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&amp;db=pubmed&amp;dopt=Abstract&amp;list_uids=2112744" class="external" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&amp;db=pubmed&amp;dopt=Abstract&amp;list_uids=2112744">PMID 2112744</a>.</cite><span class="Z3988" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&amp;rft.genre=article&amp;rft.atitle=Towards+a+natural+system+of+organisms%3A+proposal+for+the+domains+Archaea%2C+Bacteria%2C+and+Eucarya.&amp;rft.jtitle=Proc+Natl+Acad+Sci+U+S+A&amp;rft.date=1990&amp;rft.volume=87&amp;rft.issue=12&amp;rft.au=Woese+C%2C+Kandler+O%2C+Wheelis+M&amp;rft.pages=4576-9&amp;rft.issn=0027-8424&amp;rft_id=info:pmid/2112744&amp;rft_id=http%3A%2F%2Fwww.pnas.org%2Fcgi%2Freprint%2F87%2F12%2F4576" class="Z3988">&nbsp;</span></li> <li id="_note-3"><strong><a title="" href="http://en.wikipedia.org/wiki/Biology#_ref-3">^</a></strong> See: Mayr, <em>The Growth of Biological Thought</em>; Magner, <em>A History of the Life Sciences</em></li> <li id="_note-4"><strong><a title="" href="http://en.wikipedia.org/wiki/Biology#_ref-4">^</a></strong> See: Bowler, <em>Evolution</em>; Coleman, <em>Biology in the Nineteenth Century</em>;, Mayr, <em>The Growth of Biological Thought</em></li> <li id="_note-5"><strong><a title="" href="http://en.wikipedia.org/wiki/Biology#_ref-5">^</a></strong> See: Allen, <em>Life Science in the Twentieth Century</em>; Fruton, <em>Proteins, Enzymes, Genes</em>; Morange, <em>A History of Molecular Biology</em>; Smocovitis, <em>Unifying Biology</em></li>

<p><a id="Further_reading" name="Further_reading"></a>&nbsp;</p>

<li><cite class="book" id="Reference-Margulis-.5B.5B1997.5D.5D" style="fontFONT-styleSTYLE: normal;" class="book"><a title="Lynn Margulis" href="http://en.wikipedia.org/wiki/Lynn_Margulis">Margulis, Lynn</a> (<a title="1997" href="http://en.wikipedia.org/wiki/1997">1997</a>). <em>Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth</em>, 3rd edition, St. Martin's Press. <a class="internal" href="http://en.wikipedia.org/w/index.php?title=Special:Booksources&amp;isbn=0805072527">ISBN 0-8050-7252-7</a>.</cite><span class="Z3988" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&amp;rft.genre=book&amp;rft.btitle=Five+Kingdoms%3A+An+Illustrated+Guide+to+the+Phyla+of+Life+on+Earth&amp;rft.aulast=Margulis&amp;rft.aufirst=Lynn&amp;rft.date=%5B%5B1997%5D%5D&amp;rft.edition=3rd+edition&amp;rft.pub=St.+Martin%27s+Press&amp;rft.isbn=0-8050-7252-7" class="Z3988">&nbsp;</span> (many other editions)</li> <li><cite class="book" id="Reference-Campbell-.5B.5B2004.5D.5D" style="fontFONT-styleSTYLE: normal;" class="book"><a title="Neil Campbell" href="http://en.wikipedia.org/wiki/Neil_Campbell">Campbell, Neil</a> (<a title="2004" href="http://en.wikipedia.org/wiki/2004">2004</a>). <em>Biology</em>, 7th edition, Benjamin-Cummings Publishing Company. <a class="internal" href="http://en.wikipedia.org/w/index.php?title=Special:Booksources&amp;isbn=080537146X">ISBN 0-8053-7146-X</a>.</cite><span class="Z3988" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&amp;rft.genre=book&amp;rft.btitle=Biology&amp;rft.aulast=Campbell&amp;rft.aufirst=Neil&amp;rft.date=%5B%5B2004%5D%5D&amp;rft.edition=7th+edition&amp;rft.pub=Benjamin-Cummings+Publishing+Company&amp;rft.isbn=0-8053-7146-X" class="Z3988">&nbsp;</span></li> <li><cite class="book" id="Reference-Johnson-.5B.5B2005.5D.5D" style="fontFONT-styleSTYLE: normal;" class="book"><a title="Johnson George B." href="http://en.wikipedia.org/wiki/Johnson_George_B.">Johnson, George B.</a> (<a title="2005" href="http://en.wikipedia.org/wiki/2005">2005</a>). <em>Biology, Visualizing Life</em>. Holt, Rinehart, and Winston. <a class="internal" href="http://en.wikipedia.org/w/index.php?title=Special:Booksources&amp;isbn=003016723X">ISBN 0-03-016723-X</a>.</cite><span class="Z3988" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&amp;rft.genre=book&amp;rft.btitle=Biology%2C+Visualizing+Life&amp;rft.aulast=Johnson&amp;rft.aufirst=George+B.&amp;rft.date=%5B%5B2005%5D%5D&amp;rft.pub=Holt%2C+Rinehart%2C+and+Winston&amp;rft.isbn=0-03-016723-X" class="Z3988">&nbsp;</span></li>

<p><a id="External_links" name="External_links"></a>&nbsp;</p>

<div style="floatFLOAT: left;"><div class="floatnone"><span><a title="Wikibooks" class="image" href="http://en.wikipedia.org/wiki/Image:Wikibooks-logo-en.svg"><br /></a></span></div></div><div style="margin-left: 60px;"><a title="Wikibooks" href="http://en.wikipedia.org/wiki/Wikibooks">Wikibooks</a> has more on the topic of<div style="margin-left: 10px;"><em><a title="wikibooks:Special:Search/Biology" class="extiw" href="http://en.wikibooks.org/wiki/Special:Search/Biology">Biology</a></em></div></div></div><div style="float: right;" class="infobox sisterproject"><div style="float: left;"><div class="floatnone"><span><a title="" class="image" href="http://en.wikipedia.org/wiki/Image:WiktionaryWikibooks-logo-en.png"><br /></a></span></div></div><div style="margin-left: 60px;">Look up <em><strong><a title="wiktionary:Special:Search/biology" class="extiw" href="http://en.wiktionary.org/wiki/Special:Search/biology">Biology</a></strong></em> in<br /><a title="Wiktionary" href="http://en.wikipedia.org/wiki/Wiktionary">Wiktionary</a>, the free dictionary.</div></div><div class="infobox sisterproject"><div style="float: left;"><div class="floatnone"><span><a title="Wikiversity" class="image" href="http://en.wikipedia.org/wiki/Image:Wikiversity-logo-Snorky.svg"><br />

<div style="marginMARGIN-leftLEFT: 60px;">At <a title="Wikiversity" href="http://en.wikipedia.org/wiki/Wikiversity">Wikiversity</a> you can learn more about <strong>Biology</strong> at:<div style="margin-left: 10px;"><a title="v:School:Biology" class="extiw" href="http://en.wikiversity.org/wiki/School:Biology">The School of Biology</a></div></div></div><div style="border: 1px solid rgb(170, 170, 170); margin: 0.5em 0pt 0.5em 0.5em; background: rgb(249, 249, 249) none repeat scroll 0% 50%; -moz-background-clip: -moz-initial; -moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial; font-size: 85%;" class="tright"><table width="0" style="background: transparent none repeat scroll 0% 50%; -moz-background-clip: -moz-initial; -moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial;"> <tbody> <tr> <td> <div style="overflow: hidden; position: relative; width: 32px; height: 28px;"> <div style="position: absolute; top: 0px; left: 0px; z-index: 2;"><a title="Portal:Biology" class="image" href="http://en.wikipedia.org/wiki/Image:Portal.svg"><img width="28" height="28" src="http://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Portal.svg/28px-Portal.svg.png" longdesc="/wiki/Image:Portal.svg" alt="Portal:Biology" /></a></div> </div> </td> <td><em><strong><a title="Portal:Biology" href="http://en.wikipedia.org/wiki/Portal:Biology">Biology Portal</a></strong></em></td> </tr> </tbody></table>

<li><a rel="nofollow" title="[http://wwwbiosites.dnalcorg Biosites.org] </" class="external text" href="li> <li>[http://wwwbiologywiki.dnalcorg Biologywiki.org/">The Dolan DNA Learning Center: The source for timely information about your life</a>] </li> <li><a title="PhyloCode" href="http://en.wikipedia.org/wiki/PhyloCode">PhyloCode</a>, <a relclass="nofollowexternal free" title="http://www.ohiou.edu/phylocode/index.html" classrel="external freenofollow" href="http://www.ohiou.edu/phylocode/index.html">http://www.ohiou.edu/phylocode/index.html</a></li> <li><a relclass="nofollowexternal text" title="http://tolweb.org/tree/phylogeny.html" classrel="external textnofollow" href="http://tolweb.org/tree/phylogeny.html"><em>The Tree of Life</em></a>: A multi-authored, distributed Internet project containing information about phylogeny and biodiversity.</li> <li><a relclass="nofollowexternal text" title="http://ocw.mit.edu/OcwWeb/Biology/7-012Fall-2004/VideoLectures/" classrel="external textnofollow" href="http://ocw.mit.edu/OcwWeb/Biology/7-012Fall-2004/VideoLectures/">MIT video lecture series on biology</a></li> <li><a relclass="nofollowexternal text" title="http://www.openwetware.org" classrel="external textnofollow" href="http://www.openwetware.org/">A wiki site for protocol sharing run from MIT</a>.</li> <li><a relclass="nofollowexternal text" title="http://www.biology-online.org/dictionary/" classrel="external textnofollow" href="http://www.biology-online.org/dictionary/">Biology online wiki dictionary</a>.</li> <li><a relclass="nofollowexternal text" title="http://www.biologynews.net/" classrel="external textnofollow" href="http://www.biologynews.net/">Biology News Net</a>.</li>

<p><a id="Journal_links" name="Journal_links"></a>&nbsp;</p>

<li><a relclass="nofollowexternal text" title="http://biology.plosjournals.org/perlserv/?request=index-html&amp;issn=1545-7885" classrel="external textnofollow" href="http://biology.plosjournals.org/perlserv/?request=index-html&amp;issn=1545-7885">PLos Biology</a> A peer-reviewed, open-access journal published by the Public Library of Science</li> <li><a relclass="nofollowexternal text" title="http://www.biolsci.org" classrel="external textnofollow" href="http://www.biolsci.org/">International Journal of Biological Sciences</a> A biological journal publishes peer-reviewed scientific papers of significance</li> <li><a relclass="nofollowexternal text" title="http://www.press.jhu.edu/journals/perspectives_in_biology_and_medicine/index.html" classrel="external textnofollow" href="http://www.press.jhu.edu/journals/perspectives_in_biology_and_medicine/index.html">Perspectives in Biology and Medicine</a></li>