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Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
The kinesis strategy controlled by the locally and instantly evaluated well-being can be described in simple words: Animals stay longer in good conditions and leave bad conditions more quickly. If the well-being is measured by the local reproduction coefficient then the minimal reaction-diffusion model of kinesis can be written as follows: [ 3 ]
Knudsen diffusion, named after Martin Knudsen, is a means of diffusion that occurs when the scale length of a system is comparable to or smaller than the mean free path of the particles involved. An example of this is in a long pore with a narrow diameter (2–50 nm) because molecules frequently collide with the pore wall. [ 1 ]
Darwin [6] regarded such competition as having molded numerous aspects of animal behavior. Darwin particularly emphasized the striking evolution of aesthetic display in male birds. He also considered that a similar process had occurred in humans leading, for example, to the evolution of female beauty and sweeter voice and, in males, to the beard.
It is usually observed in large plant and animal cells, greater than approximately 0.1 mm [vague]. In smaller cells, the diffusion of molecules is more rapid, but diffusion slows as the size of the cell increases, so larger cells may need cytoplasmic streaming for efficient function. [1]
In very small animals, plants and bacteria, simple diffusion of gaseous metabolites is sufficient for respiratory function and no special adaptations are found to aid respiration. Passive diffusion or active transport are also sufficient mechanisms for many larger aquatic animals such as many worms, jellyfish, sponges, bryozoans and similar ...
The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World—and Us is a 2017 book by the ornithologist and evolutionary biologist Richard O. Prum about the power of aesthetic mate choice, arguing it to be an important independent agent in evolution.
Facilitated Diffusion is a passive process that relies on carrier proteins to transport glucose down a concentration gradient. [ 2 ] Secondary Active Transport is transport of a solute in the direction of increasing electrochemical potential via the facilitated diffusion of a second solute (usually an ion, in this case Na + ) in the direction ...