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The Limits to Growth (LTG) is a 1972 report [2] that discussed the possibility of exponential economic and population growth with finite supply of resources, studied by computer simulation. [3] The study used the World3 computer model to simulate the consequence of interactions between the Earth and human systems.
Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. [1] Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than the overall rate of cellular degradation (the destruction of biomolecules via the proteasome, lysosome or autophagy, or catabolism).
Linear growth is a complex process regulated by the growth hormone (GH) – insulin-like growth factor-1 axis, the thyroxine/triiodothyronine axis, androgens, estrogens, vitamin D, glucocorticoids and possibly leptin. [25] GH is secreted by the anterior pituitary gland in response to hypothalamic, pituitary and circulating factors.
The Hayflick limit, or Hayflick phenomenon, is the number of times a normal somatic, differentiated human cell population will divide before cell division stops. [ 1 ] [ 2 ] The concept of the Hayflick limit was advanced by American anatomist Leonard Hayflick in 1961, [ 3 ] at the Wistar Institute in Philadelphia , Pennsylvania.
Liebig's law has been extended to biological populations (and is commonly used in ecosystem modelling).For example, the growth of an organism such as a plant may be dependent on a number of different factors, such as sunlight or mineral nutrients (e.g., nitrate or phosphate).
There may be no natural limit to the Hydra's life span, but it is not yet clear how to estimate the age of a specimen. [citation needed] Flatworms, or Platyhelminthes, are known to be "almost immortal" as they have a great regeneration capacity, continuous growth, and binary fission type cellular division. [53]
Quizlet's primary products include digital flash cards, matching games, practice electronic assessments, and live quizzes. In 2017, 1 in 2 high school students used Quizlet. [ 4 ] As of December 2021, Quizlet has over 500 million user-generated flashcard sets and more than 60 million active users.
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