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A xerophyte (from Greek ξηρός xeros 'dry' + φυτόν phuton 'plant') is a species of plant that has adaptations to survive in an environment with little liquid water. Examples of xerophytes include cacti, pineapple and some gymnosperm plants. The morphology and physiology of xerophytes are adapted to conserve water during dry periods.
xerophyte widespread in the family; Mesembryanthemum crystallinum is a rare instance of an halophyte that displays CAM [36] Cactaceae: xerophyte Almost all cacti have obligate Crassulacean Acid Metabolism in their stems; the few cacti with leaves may have C 3 Metabolism in those leaves; [37] seedlings have C 3 Metabolism. [38] Portulacaceae ...
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution which in this case is represented by body fluid) to keep the body fluids from becoming too diluted or concentrated.
The membrane used in the process is a generally non-porous layer, so there will not be a severe leakage of gas through the membrane. The performance of the membrane depends on permeability and selectivity. Permeability is affected by the penetrant size. Larger gas molecules have a lower diffusion coefficient.
Kinetic diameter. Kinetic diameter is a measure applied to atoms and molecules that expresses the likelihood that a molecule in a gas will collide with another molecule. It is an indication of the size of the molecule as a target. The kinetic diameter is not the same as atomic diameter defined in terms of the size of the atom's electron shell ...
Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata. Light is the main trigger for the opening or closing. Each guard cell has a relatively thick and thinner cuticle on the pore-side and a thin one opposite it. As water enters the cell, the thin side bulges outward ...
Permeability is a measure of how easily an ion can cross the membrane. It is normally measured as the (electrical) conductance and the unit, siemens, corresponds to 1 C·s −1 ·V −1, that is one coulomb per second per volt of potential. So, in a resting membrane, while the driving force for potassium is low, its permeability is very high.
Molecules are randomly oriented in the bulk solution. Assuming 1/6 of the molecules has the right orientation to the surface binding sites, i.e. 1/2 of the z-direction in x, y, z three dimensions, thus the concentration of interest is just 1/6 of the bulk concentration.