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a chemical messenger produced and released by a cell or a gland in one part of the body of the organism that affect cells in other parts of the organism. In essence, it is a chemical messenger that transports a signal from one cell to another. Only a small amount of hormone is required to alter cell metabolism. Hormones in animals are most often transported in the blood.
a muscular structure on the floor of the mouth of most vertebrates, which manipulates food for ...
the seepage of acidic, contaminated water from disused mines and mine dumps.