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Phanerozoic carbon dioxide concentrations have been governed partially by a 26 million year oceanic crustal cycle. [71] Since the Devonian, large swings in carbon dioxide of 2,000 ppm or more were uncommon over short timescales. [ 72 ]
All organisms follow a specific sequence in their development, [9] beginning with gestation and ending with death, which is known as the life cycle. Events in between usually include birth, childhood, maturation, reproduction, and senescence, and together these comprise the life history strategy of that organism.
Alternation of generations (also known as metagenesis or heterogenesis) [1] is the predominant type of life cycle in plants and algae. In plants both phases are multicellular : the haploid sexual phase – the gametophyte – alternates with a diploid asexual phase – the sporophyte .
In biology, a biological life cycle (or just life cycle when the biological context is clear) is a series of stages of the life of an organism, that begins as a zygote, often in an egg, and concludes as an adult that reproduces, producing an offspring in the form of a new zygote which then itself goes through the same series of stages, the ...
Molecular biology – study of biology and biological functions at the molecular level, with some cross over from biochemistry. Structural biology – a branch of molecular biology, biochemistry, and biophysics concerned with the molecular structure of biological macromolecules. Health sciences and human biology – biology of humans.
The word is derived from the Greek φαίνω (phainō), "to show, to bring to light, make to appear" [6] + λόγος (), amongst others "study, discourse, reasoning" [7] and indicates that phenology has been principally concerned with the dates of first occurrence of biological events in their annual cycle.
The authors describe each turning as lasting circa 21 years. Four turnings make up a full cycle of circa 85 years, [45] which the authors term a saeculum, after the Latin word meaning both "a long human life" and "a natural century". [46] Generational change drives the cycle of turnings and determines its periodicity. As each generation ages ...
Biology is the scientific study of life. [1] [2] [3] It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. [1] [2] [3] For instance, all organisms are made up of at least one cell that processes hereditary information encoded in genes, which