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Chargaff's rules. Chargaff's rules (given by Erwin Chargaff) state that in the DNA of any species and any organism, the amount of guanine should be equal to the amount of cytosine and the amount of adenine should be equal to the amount of thymine. Further, a 1:1 stoichiometric ratio of purine and pyrimidine bases (i.e., A+G=T+C) should exist.
Biological rules. The pygmy mammoth is an example of insular dwarfism, a case of Foster's rule, its unusually small body size an adaptation to the limited resources of its island home. A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms.
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).
Ecological efficiency is a combination of several related efficiencies that describe resource utilization and the extent to which resources are converted into biomass. [ 1] Exploitation efficiency is the amount of food ingested divided by the amount of prey production ( ) Assimilation efficiency is the amount of assimilation divided by the ...
An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bioproductivity at each trophic level in an ecosystem . A pyramid of energy shows how much energy is retained in the form of new biomass from each trophic level, while a pyramid ...
Dunbar's number. Dunbar's number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—relationships in which an individual knows who each person is and how each person relates to every other person. [ 1][ 2] This number was first proposed in the 1990s by British anthropologist Robin ...
Organism. An organism is defined in a medical dictionary as any living thing that functions as an individual. [ 1] Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what is an organism.
Pareto principle. The Pareto principle may apply to fundraising, i.e. 20% of the donors contributing towards 80% of the total. The Pareto principle (also known as the 80/20 rule, the law of the vital few and the principle of factor sparsity [1] [2]) states that for many outcomes, roughly 80% of consequences come from 20% of causes (the "vital ...