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The gravity model of migration is a model in urban geography derived from Newton's law of gravity, and used to predict the degree of migration interaction between two places. [1] In 1941, astrophysicist John Q. Stewart [ 2 ] applied Newton's law to the social sciences, establishing a theoretical foundation for the field of social physics.
Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant in response to gravity pulling on it. It also occurs in fungi. Gravity can be either "artificial gravity" [clarification needed] or natural gravity. It is a general feature of all higher and many lower plants as well as other organisms.
Gravitation also explains astronomical phenomena on more modest scales, such as planetary orbits, as well as everyday experience: objects fall; heavy objects act as if they were glued to the ground, and animals can only jump so high. Gravitation was the first interaction to be described mathematically.
That is, in stronger gravitational fields the size of cells decreases, and in weaker gravitational fields the size of cells increases. Gravity is thus a limiting factor in the growth of individual cells. Cells which were naturally larger than the size that gravity alone would allow for had to develop means to protect against internal sedimentation.
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak which eat crustaceans.. A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as earthworms and woodlice ...
A simplified food web illustrating a three-trophic food chain (producers-herbivores-carnivores) linked to decomposers. The movement of mineral nutrients through the food chain, into the mineral nutrient pool, and back into the trophic system illustrates ecological recycling. The movement of energy, in contrast, is unidirectional and noncyclic.
The nature–culture divide is the notion of a dichotomy between humans and the environment. [1] It is a theoretical foundation of contemporary anthropology that considers whether nature and culture function separately from one another, or if they are in a continuous biotic relationship with each other.
A freshwater aquatic food web. The blue arrows show a complete food chain (algae → daphnia → gizzard shad → largemouth bass → great blue heron). A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community.