Browse categories
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Anatomy
1,049 questions A branch of biology dealing with the structure of organisms.
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Organisms
388 questions Any living biological entity, such as an animal, plant, fungus, or bacterium.
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Eukaryota
79 questions One of the three domains of life (the others being BACTERIA and ARCHAEA), also called Eukarya. These are organisms whose cells are enclosed in membranes and possess a nucleus. They comprise almost all multicellular and many unicellular organisms, and are traditionally divided into groups (sometimes called kingdoms) including ANIMALS; PLANTS; FUNGI; and various algae and other taxa that were previously part of the old kingdom Protista.
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Archaea
5 questions One of the three domains of life (the others being BACTERIA and Eukarya), formerly called Archaebacteria under the taxon Bacteria, but now considered separate and distinct. They are characterized by: (1) the presence of characteristic tRNAs and ribosomal RNAs; (2) the absence of peptidoglycan cell walls; (3) the presence of ether-linked lipids built from branched-chain subunits; and (4) their occurrence in unusual habitats. While archaea resemble bacteria in morphology and genomic organization, they resemble eukarya in their method of genomic replication. The domain contains at least four kingdoms: CRENARCHAEOTA; EURYARCHAEOTA; NANOARCHAEOTA; and KORARCHAEOTA.
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Bacteria
46 questions One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE
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Viruses
12 questions Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells.
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Organism Forms
7 questions Specific states or life cycle stages of organisms. These include post-embryonic stages of insects, symbiotic relationships between organisms, and reproductive elements such as spores.
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Diseases
1,356 questions Any impairment of normal physiological function affecting all or part of an organism, esp a specific pathological change caused by infection, stress, etc, producing characteristic symptoms; illness or sickness in general.
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Chemicals and Drugs
853 questions Any substance used in or resulting from a reaction involving changes to atoms or molecules, especially one derived artificially for practical use and any synthetic, semisynthetic, or natural chemical substance used in the treatment, prevention, or diagnosis of disease, or for other medical reasons.
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Analytical, Diagnostic and Therapeutic Techniques and Equipment
359 questions
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Psychiatry and Psychology
162 questions The branches of medicine concerned with the diagnosis and treatment of mental illness and the scientific study of all forms of human and animal behaviour, sometimes concerned with the methods through which behaviour can be modified.
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Phenomena and Processes
97 questions
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Disciplines and Occupations
28 questions
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Anthropology, Education, Sociology and Social Phenomena
98 questions
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Technology, Industry, Agriculture
84 questions
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Humanities
80 questions The study of literature, philosophy, and the arts.
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Information Science
219 questions The field of knowledge, theory, and technology dealing with the collection of facts and figures, and the processes and methods involved in their manipulation, storage, dissemination, publication, and retrieval. It includes the fields of COMMUNICATION; PUBLISHING; LIBRARY SCIENCE; and informatics.
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Named Groups
38 questions
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Health Care
1,264 questions
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Publication Characteristics
30 questions
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Geographicals
23 questions The study of the natural features of the earth's surface, including topography, climate, soil, vegetation, etc, and man's response to them.
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