Mucous membrane, membrane lining body cavities and canals that lead to the outside, chiefly the respiratory, digestive, and urogenital tracts. Mucous membranes line many tracts and structures of the body, including the mouth, nose, eyelids, trachea (windpipe) and lungs, stomach and intestines, and the ureters, urethra, and urinary bladder.
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O horizon
it is most important for growth of crops
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Vertebrates have back bones or spines that give there body support.
