AP BIOLOGY

Detailed explanation-1: -The chemistry of the Casparian strip has been described as composed of suberin. According to some studies, 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.

Detailed explanation-2: -The compounds deposited in the Casparian strips are suberin, lignin and some structural proteins, which are capable of reducing the diffusive apoplastic flow of water and solutes into the stele.

Detailed explanation-3: -transport function …into roots is the so-called Casparian strip, a conspicuously thickened wall area one cell layer deep surrounding primary roots; it prevents excess soil solution from being pulled directly into the central part of the root where the xylem is located.

Detailed explanation-4: -Early in the development of the endodermis, suberin (a fatty substance) is deposted in bands on the transverse walls and radial walls in the longitudinal direction, forming the casparian strip (Fig. 14.6).

Detailed explanation-5: -Casparian strip A band of waterproof, corky tissue that is found on the side and walls of the endodermis of roots. The strip prevents water from entering the pericycle except through the cytoplasm of endodermal cells; this may be important in producing root pressure.