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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 ...
(The "living fossil" coelacanth is a related lobe-finned fish without these shallow-water adaptations.) Tetrapod fishes used their fins as paddles in shallow-water habitats choked with plants and detritus. The universal tetrapod characteristics of front limbs that bend backward at the elbow and hind limbs that bend forward at the knee can ...
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
The life span of an individual depends on two major factors, genetics and lifestyle choices. [211] For various reasons, including biological/genetic causes, women live on average about four years longer than men. [212] As of 2018, the global average life expectancy at birth of a girl is estimated to be 74.9 years compared to 70.4 for a boy.
Fertilization is the fusing of the gametes; a sperm cell and an ovum (egg cell) fuse to form a single-cell zygote.This is the beginning of the diploid phase of the human life cycle after two genetically unique haploid cells created via meiosis and chromosomal translocation combine their DNA and begin to develop into a multi-cellular organism.
People are living longer lives, but not healthier ones—and there are four main reasons why.. That was the assertion of Roy Gori—president and CEO of Manulife, Canada’s largest insurance ...
Documentary films about people by age (3 C) > Developmental stage theories (1 C, 14 P) A. Adolescence (19 C, 42 P) ... Pages in category "Human life stages"
One systemic definition of life is that living things are self-organizing and autopoietic (self-producing). Variations of this include Stuart Kauffman's definition as an autonomous agent or a multi-agent system capable of reproducing itself, and of completing at least one thermodynamic work cycle. [27]