जीवशास्त्रं
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जीवशास्त्रं यस्मिन् शास्त्रे विविधानां जीवानां समग्राध्ययनं विद्यते तच्छास्त्रं जीवशास्त्रं कथ्यते। समस्तानां प्राणिनां जीवनस्य सूक्ष्म रूपेण अवलोकनम् अध्ययनञ्च जीवशास्त्रस्य विषयः भवति।
Contents |
[edit] भूमिका
[edit] क्षेत्रा:
[edit] इतिहास
प्रसिद्ध जीवशास्त्री -- जीवशास्त्र ईतिहास -- Nobel prize in physiology or medicine -- जीवशास्त्र व अंगीय रसायनशास्त्र कालचक्र
[edit] विषय-सूची
[edit] विकासवाद
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.
[edit] 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.
Traditionally, living things were divided into five kingdoms:
- Monera -- Protista -- Fungi -- Plantae -- Animalia
However, this five-kingdom system is now considered by many to be outdated. More modern alternatives generally begin with the three-domain system:
- Archaea (originally Archaebacteria) -- Bacteria (originally Eubacteria) -- Eukaryota
These domains reflect whether cells have nuclei or not as well as differences in cell exteriors.
There is also a series of intracellular "parasites" that are progressively less alive in terms of being metabolically active:
- Viruses -- Viroids -- Prions
[edit] अन्य विषया:
- Eukaryote
- Origin of life
- Morphology
- Environment
- Ecosystem
- Biologist
- Physician
- Unsolved problems in biology
- List of conservation topics
