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जीवशास्त्रं
जीवशास्त्रं जीवेन शास्त्रं इति. एतस्य विषया: जीवस्य उत्पत्ति, व्यवहारं, एवं वातावरणं.
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2 विकासवाद 3 वर्गीकरण 4 अन्य विषया: |
Traditionally, living things were divided into five kingdoms:
There is also a series of intracellular "parasites" that are progressively less alive in terms of being metabolically active:
भूमिका
Biology encompasses a broad spectrum of academic fields that are often viewed as independent disciplines. Together, they study life over a wide range of scales:क्षेत्रा:
Aerobiology -- Anatomy -- Arachnology-- Astrobiology -- Biochemistry -- Bionics -- Biogeography -- Bioinformatics -- Biomechanics -- Biophysics-- Biotechnology -- Botany -- Cell biology -- Chorology -- Cladistics -- Crustaceology -- Cryptozoology -- Cycles -- Cytology -- Developmental biology -- Disease (Genetic diseases, Infectious diseases) -- Ecology (Theoretical ecology, Symbiology, Autecology, Synecology) -- Ethology -- Entomology -- Evolutionary biology (Evolution) -- Evolutionary developmental biology -- Freshwater biology -- Genetics (Population genetics, Quantitative genetics, Genomics, Proteomics) -- Herpetology -- Histology -- Human biology (Anthropology) -- Ichthyology -- Immunology -- Infectious diseases -- Pathology -- Epidemiology -- Limnology -- Malacology -- Mammalogy -- Marine biology -- Microbiology (Bacteriology) -- Molecular biology -- Morphology -- Mycology / Lichenology --- Myrmecology --- Neuroscience (Neuroanatomy, Neurophysiology, Systems neuroscience, Biological psychology, Psychiatry, Psychopharmacology, Behavioral science, Neuroethology, Psychophysics, Computational neuroscience, Cognitive neuroscience, Cognitive science)-- Oncology (the study of cancer) -- Ontogeny -- Origin of life -- Ornithology -- Paleontology (Paleobotany, Paleozoology)-- Parasitology -- Phycology (Algology) -- Phylogeny (Phylogenetics, Phylogeography) -- Physiology -- Phytopathology -- Structural biology -- Taxonomy -- Toxicology (the study of poisons and pollution) -- Virology -- Xenobiology -- ZoologyRelated disciplines
Medicine -- Physical anthropologyविकासवाद
One of the central, organizing concepts in biology is that all life has descended from a common origin through a process of evolution. Charles Darwin established evolution as a viable theory by articulating its driving force: natural selection. Genetic drift was embraced as an additional mechanism in the so-called modern synthesis. The evolutionary history of a species—which tells the characteristics of the various species from which it descended—together with its genealogical relationship to every other species is called its phylogeny. Widely varied approaches to biology generate information about phylogeny. These include the comparisons of DNA sequences conducted within molecular biology or genomics, and comparisons of fossils or other records of ancient organisms in paleontology. Biologists organize and analyze evolutionary relationships through various methods, including phylogenetics, phenetics, and cladistics. Major events in the evolution of life, as biologists currently understand them, are summarized on this evolutionary timeline.वर्गीकरण
The classification of living things is called systematics, or taxonomy, and should reflect the evolutionary trees (phylogenetic trees) of the different organisms. Taxonomy piles up organisms in groups called taxa, while systematics seeks their relationships. The dominant system is called Linnaean taxonomy, which includes ranks and binomial nomenclature. How organisms are named is governed by international agreements such as the International Code of Botanical Nomenclature (ICBN), the International Code of Zoological Nomenclature (ICZN), and the International Code of Nomenclature of Bacteria (ICNB). A fourth Draft BioCode was published in 1997 in an attempt to standardize naming in the three areas, but it does not appear to have yet been formally adopted. The International Code of Virus Classification and Nomenclature (ICVCN) remains outside the BioCode.
However, this five-kingdom system is now considered by many to be outdated. More modern alternatives generally begin with the three-domain system:
These domains reflect whether cells have nuclei or not as well as differences in cell exteriors.अन्य विषया:
