a major function of the casparian strip of the endodermal cells of a root is to
Casparian strip The chemistry of the Casparian strip has been described as composed of suberin. According to some studies,[3] the Casparian strip begins as a localized deposition of phenolic and unsaturated fatty substances in the middle lamella between the radial walls, as partly oxidized films. The primary wall becomes encrusted with and later thickened by deposits of similar substances on the inside of that wall. The encrustation of the cell wall by the material constituting the Casparian strip presumably plugs the pores that would have otherwise allowed the movement of water and nutrients via capillary action along that path.[4] The cytoplasm of the endodermal cell is firmly attached to the Casparian strip so that it does not readily separate from the strip when the cells are subjected to contraction of the protoplasts. At the root, the casparian strip is embedded within the cell wall of endodermal cells in the non-growing region of the root behind the root tip.[5] Here, the casparian strip serves as a boundary layer separating the apoplast of the cortex from the apoplast of the vascular tissue thereby blocking diffusion of material between the two.[6] This separation forces water and solutes to pass through the plasma membrane via a symplastic route in order to cross the endodermis layer.[5]
Stockholm Water Prize 2006: Professor Asit K. Biswas, The Third World Center for Water Management
Ascaris lumbricoides Infections with these parasites are more common where sanitation is poor,[10] and raw human feces are used as fertilizer.
Eye Rods cannot distinguish colours, but are responsible for low-light (scotopic) monochrome (black-and-white) vision; they work well in dim light as they contain a pigment, rhodopsin (visual purple), which is sensitive at low light intensity, but saturates at higher (photopic) intensities. Rods are distributed throughout the retina but there are none at the fovea and none at the blind spot. Rod density is greater in the peripheral retina than in the central retina.