The process is called diffusion, and it requires no energy input.
The theory of fluid intelligence is based on the distinction between the fluid and crystal intelligences. The crystal intelligence is based on the knowledge that one has already and the the fluid intelligence is the intelligence to respond to future and unpredictable challenges.
I think that this distinction is very fitting and that the fluid intelligence was probably the one that drove human evolution; and perhaps is the more relevant of the intelligences.
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Answer:
All cells have an outer plasma membrane that regulates not only what enters the cell, but also how much of any given substance comes in. Unlike prokaryotes, eukaryotic cells also possess internal membranes that encase their organelles and control the exchange of essential cell components.
The universality of marriage within different societies and cultures is attributed to the many basic social and personal functions for which it provides structure, such as sexual gratification and regulation, division of labour between the sexes, economic production and consumption, and satisfaction of personal needs for affection, status, and companionship. Perhaps its strongest function concerns procreation, the care of children and their education and socialization, and regulation of lines of descent.
