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Hypothesis in Biological Definition

Abiogenesis

... abiogenesis increased, and it became a tempting hypothesis that whilst the higher forms of life arose only ... under debate; see, for example, RNA world hypothesis , proteinoid , Miller experiment . ... Leslie_Orgel co-proposed Directed Panspermia hypothesis for how life started on Earth. However, it ...

Hardy-Weinberg principle

... is assumed to be negligibly small. The null hypothesis is that the population is in Hardy–Weinberg proportions, and the alternative hypothesis is that the population is not in ... the χ 2 value is less than this, the null hypothesis that the population is in Hardy–Weinberg ...

Natural selection

... is continuous. For example, the Red Queen hypothesis suggests that sex might have evolved to help ... in poetic verse. His formal exposition of the hypothesis lacks a structured formulation, but has enough merit to be considered a possibility. Matthew's hypothesis had appeared in an appendix to his book on ...

Neutral theory of molecular evolution

... or no biological effect. A second assertion or hypothesis of the neutral theory is that most evolutionary ... widely used as a "null model" for so-called null hypothesis testing. Researchers typically apply such a test ... is much less than the prediction, the null hypothesis has failed, and researchers may reasonably assume ...

Origin of life

... the RNA world Main article: RNA world hypothesis The RNA world hypothesis, for example, ... models Clay theory of the origin of life A hypothesis for the origin of life based on clay was ... An alternative to Earthly abiogenesis is the hypothesis that primitive life may have originally formed ...

Prion

... 1 Prusiner's Prion hypothesis 2 Useful Prions 3 Yeast Prions 4 ... 7 External links Prusiner's Prion hypothesis Prions were first hypothesized in 1982 by ... that are necessary for reproduction. The prion hypothesis was developed to explain why the mysterious ...

RNA

... to DNA 3 Synthesis 4 RNA world hypothesis 5 Biological role 5.1 Messenger RNA ... gene expression is regulated. RNA world hypothesis The RNA world hypothesis proposes that the universal ancestor to all life ...

Chi-square test

... A chi-square test is any statistical hypothesis test in which the test statistic has a chi-square distribution if the null hypothesis is true. These include: Pearson's chi-square test Some ...

Endosymbiotic theory

... based largely on the discovery that they contain DNA. The endosymbiotic hypothesis was popularized by Lynn Margulis . In her 1981 work Symbiosis in Cell ... of the evolution of flagella , and has more on Margulis) Hydrogen hypothesis External links The Birth of Complex Cells - by Christian de ...

Extinction

... time on Earth. However, recent technological advances have encouraged the hypothesis that through the process of cloning , extinct species may be "brought ... ). Mass extinctions are a key part of the punctuated equilibrium hypothesis of Stephen Jay Gould and Niles Eldredge . See: Time Frames: The ...

Francis Crick

... biology and switched to neuroscience. Crick's book The Astonishing hypothesis makes the argument that neuroscience now has the tools required to ... was a well-known atheist who also advocated directed panspermia as a hypothesis for how life started on Earth. Crick was also one of the original ...

Lyon hypothesis

... The Lyon hypothesis states that in cells with multiple X chromosomes , all but one is ... women, and a further 10% of genes were switched on in some women. The hypothesis was first stated by Mary F. Lyon in 1961 while she was studying the ...

Mitochondrion

... as prokaryotic endosymbionts . Essentially this widely accepted hypothesis postulates that the ancestors of modern mitochondria were independent ... Tomography See also Endosymbiotic theory Chemiosmotic hypothesis Chloroplast Submitochondrial particle Mitochondrial disease ...

Mitochondrion

... as prokaryotic endosymbionts . Essentially this widely accepted hypothesis postulates that the ancestors of modern mitochondria were independent ... Tomography See also Endosymbiotic theory Chemiosmotic hypothesis Chloroplast Submitochondrial particle Mitochondrial disease ...

Muller's ratchet

... In genetics , Muller 's ratchet is a hypothesis that explains how functionally important genes may be lost when ... better in small populations than larger ones. See the Red Queen for the hypothesis that is generally regarded as being superior, though note that the two ...

Sociobiology

... proceeds: A social behaviour is first explained as a sociobiological hypothesis by finding an evolutionarily stable strategy that matches the observed ... but usually, a well-formed strategy will predict gene frequencies. The hypothesis can be confirmed by establishing a correlation between the gene ...

Species

... status The naming of a particular species should be regarded as a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be confirmed or refuted. Sometimes, especially in the past when ...

Alfred Russel Wallace

... ), to collect specimens and study nature. His observations of the marked zoological differences across a narrow zone in the archipelago led to his hypothesis of the zoogeographical boundary now known as the Wallace line . One of his better known species descriptions during this trip is the gliding tree ...

Archaea

... each represent a primary line of descent that diverged early on from an ancestral progenote with poorly developed genetic machinery. This hypothesis is reflected in the name Archaea, from the Greek archae or ancient. Later he treated these groups formally as domains , each comprising several ...

Barr body

... inactive X-chromosome and to bring about its compaction to form the Barr body. See also X-inactivation Sex-determination system Lyon hypothesis . ...

Chemiosmotic hypothesis

... The Chemiosmotic hypothesis is the proposal in 1961, by Peter D. Mitchell, that the mitochondrion functioned as a kind of electrochemical capacitor , using the energy of ...

Charles Darwin

... era began. In mid July he began a secret notebook on transmutation, his "B" notebook , with a title page headed Zonomia . He developed the hypothesis that, for example, where every island in the Galpagos Archipelago had its own kind of tortoise, these had originated from a single tortoise species ...

Down syndrome

... peroxide and water . Oxygen radicals produced in cells can be damaging to cellular structures, hence the important role of SOD. However, the hypothesis says that once SOD activity increases disproportionately to enzymes responsible for removal of hydrogen peroxide (e.g., glutathione peroxidase ), ...

Ernst Haeckel

... descent) have been named the " recapitulation theory ", summed up in the phrase, "ontogeny recapitulates phylogeny". Haeckel's efforts to prove this hypothesis were probably misguided and inaccurate. Haeckel was also known for his "biogenic theory ", in which he suggested that the development of races ...

Genetics

... have used and continue to use to perpetuate themselves. This definition grows out of work on the origin of life , specifically the RNA world hypothesis . Population, quantitative and ecological genetics Main articles: Population genetics , Quantitative genetics , Ecological genetics ...

Gregor Mendel

... accuse Mendel of scientific malpractice or call it a scientific fraud — reproduction of his experiments has demonstrated the accuracy of his hypothesis — however, the results have continued to be a mystery for many, and he is generally suspected of having "smoothed" his data to some degree (not ...

Homeostasis

... potential triggers the generation of a much larger action potential . (See also leverage points .) Ecological homeostasis In the Gaia hypothesis , James Lovelock stated that the entire mass of living matter on Earth (or any planet with life) functions as a vast organism that actively ...

Lynn Margulis

... Lynn Margulis (born 1938 ) is a biologist and a professor at the University of Massachusetts Amherst . In 1967 she proposed a contentious new hypothesis which became her most important scientific contribution as the endosymbiotic theory of the origin of mitochondria as separate organisms that long ...

Neurospora crassa

... mutations . They then observed failures in metabolic pathways caused by errors in specific enzymes . This led to the "one gene, one enzyme" hypothesis that states that specific genes code for specific proteins . In the 24 April 2003 issue of Nature , the genome of N. crassa was reported ...

Nutrition

... reduced their quality of life so considerably as to negate any possible advantages of lengthening their lives. Underlying this research was the hypothesis that oxidative damage was the agent which accelerated aging, and that aging was retarded when the amount of carbohydrates was reduced through dietary ...

Parasitology

... biology , where parasites are used to identify different populations of the same fish. This forms an interesting application of the Red Queen hypothesis . Taxonomy and phylogenetics The huge diversity within the parasitic animals creates a challenge for biologists to describe and catalogue ....

Phylogeny

... phylogeny ", i.e. that the development of an organism exactly mirrors the evolutionary development of the species. The early version of this hypothesis has since been rejected as being oversimplified and misleading. However, modern biology recognizes numerous connections between ontogeny and ...

Speciation

... to the creation of new species, each typically based on any of the Darwinian theories of biological evolution . Most of these ideas share the hypothesis that speciation occurs when a parent species (also referred to as a common ancestor) splits into two (or more) reproductively-isolated populations, ...

Symbiogenesis

... from cyanobacteria captured by a protozoan . Today both chloroplasts and mitochondria are believed to have such an origin; see endosymbiotic hypothesis . In Acquiring Genomes: A Theory of the Origins of Species , Lynn Margulis argued that symbiogenesis was the primary force in evolution . ...

Astrobiology

... links Overview Although this is currently a speculative field, the presence of life in the rest of the Universe is a verifiable hypothesis (though it has yet to be verified), making xenobiology a valid field for scientific enquiry. Likewise, computer simulations of basic life processes ...
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